diff --git a/beego.go b/beego.go
index c22719c6..640fb5ab 100644
--- a/beego.go
+++ b/beego.go
@@ -221,7 +221,7 @@ func Run() {
 
 	middleware.VERSION = VERSION
 	middleware.AppName = AppName
-	middleware.RegisterErrorHander()
+	middleware.RegisterErrorHandler()
 
 	if EnableAdmin {
 		go BeeAdminApp.Run()
diff --git a/middleware/error.go b/middleware/error.go
index 35d9eb59..5c12b533 100644
--- a/middleware/error.go
+++ b/middleware/error.go
@@ -61,6 +61,7 @@ var tpl = `
 </html>
 `
 
+// render default application error page with error and stack string.
 func ShowErr(err interface{}, rw http.ResponseWriter, r *http.Request, Stack string) {
 	t, _ := template.New("beegoerrortemp").Parse(tpl)
 	data := make(map[string]string)
@@ -175,13 +176,14 @@ var errtpl = `
 </html>
 `
 
+// map of http handlers for each error string.
 var ErrorMaps map[string]http.HandlerFunc
 
 func init() {
 	ErrorMaps = make(map[string]http.HandlerFunc)
 }
 
-//404
+// show 404 notfound error.
 func NotFound(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -199,7 +201,7 @@ func NotFound(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//401
+// show 401 unauthorized error.
 func Unauthorized(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -215,7 +217,7 @@ func Unauthorized(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//403
+// show 403 forbidden error.
 func Forbidden(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -232,7 +234,7 @@ func Forbidden(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//503
+// show 503 service unavailable error.
 func ServiceUnavailable(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -248,7 +250,7 @@ func ServiceUnavailable(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
-//500
+// show 500 internal server error.
 func InternalServerError(rw http.ResponseWriter, r *http.Request) {
 	t, _ := template.New("beegoerrortemp").Parse(errtpl)
 	data := make(map[string]interface{})
@@ -262,15 +264,18 @@ func InternalServerError(rw http.ResponseWriter, r *http.Request) {
 	t.Execute(rw, data)
 }
 
+// show 500 internal error with simple text string.
 func SimpleServerError(rw http.ResponseWriter, r *http.Request) {
 	http.Error(rw, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 }
 
+// add http handler for given error string.
 func Errorhandler(err string, h http.HandlerFunc) {
 	ErrorMaps[err] = h
 }
 
-func RegisterErrorHander() {
+// register default error http handlers, 404,401,403,500 and 503.
+func RegisterErrorHandler() {
 	if _, ok := ErrorMaps["404"]; !ok {
 		ErrorMaps["404"] = NotFound
 	}
@@ -292,6 +297,8 @@ func RegisterErrorHander() {
 	}
 }
 
+// show error string as simple text message.
+// if error string is empty, show 500 error as default.
 func Exception(errcode string, w http.ResponseWriter, r *http.Request, msg string) {
 	if h, ok := ErrorMaps[errcode]; ok {
 		isint, err := strconv.Atoi(errcode)
diff --git a/middleware/exceptions.go b/middleware/exceptions.go
index 5bf85956..b221dfcb 100644
--- a/middleware/exceptions.go
+++ b/middleware/exceptions.go
@@ -2,16 +2,19 @@ package middleware
 
 import "fmt"
 
+// http exceptions
 type HTTPException struct {
 	StatusCode  int // http status code 4xx, 5xx
 	Description string
 }
 
+// return http exception error string, e.g. "400 Bad Request".
 func (e *HTTPException) Error() string {
-	// return `status description`, e.g. `400 Bad Request`
 	return fmt.Sprintf("%d %s", e.StatusCode, e.Description)
 }
 
+// map of http exceptions for each http status code int.
+// defined 400,401,403,404,405,500,502,503 and 504 default.
 var HTTPExceptionMaps map[int]HTTPException
 
 func init() {
diff --git a/orm/cmd.go b/orm/cmd.go
index 97545da4..95be7f4a 100644
--- a/orm/cmd.go
+++ b/orm/cmd.go
@@ -16,6 +16,7 @@ var (
 	commands = make(map[string]commander)
 )
 
+// print help.
 func printHelp(errs ...string) {
 	content := `orm command usage:
 
@@ -31,6 +32,7 @@ func printHelp(errs ...string) {
 	os.Exit(2)
 }
 
+// listen for orm command and then run it if command arguments passed.
 func RunCommand() {
 	if len(os.Args) < 2 || os.Args[1] != "orm" {
 		return
@@ -58,6 +60,7 @@ func RunCommand() {
 	}
 }
 
+// sync database struct command interface.
 type commandSyncDb struct {
 	al        *alias
 	force     bool
@@ -66,6 +69,7 @@ type commandSyncDb struct {
 	rtOnError bool
 }
 
+// parse orm command line arguments.
 func (d *commandSyncDb) Parse(args []string) {
 	var name string
 
@@ -78,6 +82,7 @@ func (d *commandSyncDb) Parse(args []string) {
 	d.al = getDbAlias(name)
 }
 
+// run orm line command.
 func (d *commandSyncDb) Run() error {
 	var drops []string
 	if d.force {
@@ -208,10 +213,12 @@ func (d *commandSyncDb) Run() error {
 	return nil
 }
 
+// database creation commander interface implement.
 type commandSqlAll struct {
 	al *alias
 }
 
+// parse orm command line arguments.
 func (d *commandSqlAll) Parse(args []string) {
 	var name string
 
@@ -222,6 +229,7 @@ func (d *commandSqlAll) Parse(args []string) {
 	d.al = getDbAlias(name)
 }
 
+// run orm line command.
 func (d *commandSqlAll) Run() error {
 	sqls, indexes := getDbCreateSql(d.al)
 	var all []string
@@ -243,6 +251,10 @@ func init() {
 	commands["sqlall"] = new(commandSqlAll)
 }
 
+// run syncdb command line.
+// name means table's alias name. default is "default".
+// force means run next sql if the current is error.
+// verbose means show all info when running command or not.
 func RunSyncdb(name string, force bool, verbose bool) error {
 	BootStrap()
 
diff --git a/orm/cmd_utils.go b/orm/cmd_utils.go
index 6fcb4b01..8f6d94db 100644
--- a/orm/cmd_utils.go
+++ b/orm/cmd_utils.go
@@ -12,6 +12,7 @@ type dbIndex struct {
 	Sql   string
 }
 
+// create database drop sql.
 func getDbDropSql(al *alias) (sqls []string) {
 	if len(modelCache.cache) == 0 {
 		fmt.Println("no Model found, need register your model")
@@ -26,6 +27,7 @@ func getDbDropSql(al *alias) (sqls []string) {
 	return sqls
 }
 
+// get database column type string.
 func getColumnTyp(al *alias, fi *fieldInfo) (col string) {
 	T := al.DbBaser.DbTypes()
 	fieldType := fi.fieldType
@@ -79,6 +81,7 @@ checkColumn:
 	return
 }
 
+// create alter sql string.
 func getColumnAddQuery(al *alias, fi *fieldInfo) string {
 	Q := al.DbBaser.TableQuote()
 	typ := getColumnTyp(al, fi)
@@ -90,6 +93,7 @@ func getColumnAddQuery(al *alias, fi *fieldInfo) string {
 	return fmt.Sprintf("ALTER TABLE %s%s%s ADD COLUMN %s%s%s %s", Q, fi.mi.table, Q, Q, fi.column, Q, typ)
 }
 
+// create database creation string.
 func getDbCreateSql(al *alias) (sqls []string, tableIndexes map[string][]dbIndex) {
 	if len(modelCache.cache) == 0 {
 		fmt.Println("no Model found, need register your model")
diff --git a/orm/db.go b/orm/db.go
index c6e92ec9..f12e76fb 100644
--- a/orm/db.go
+++ b/orm/db.go
@@ -15,7 +15,7 @@ const (
 )
 
 var (
-	ErrMissPK = errors.New("missed pk value")
+	ErrMissPK = errors.New("missed pk value") // missing pk error
 )
 
 var (
@@ -45,12 +45,15 @@ var (
 	}
 )
 
+// an instance of dbBaser interface/
 type dbBase struct {
 	ins dbBaser
 }
 
+// check dbBase implements dbBaser interface.
 var _ dbBaser = new(dbBase)
 
+// get struct columns values as interface slice.
 func (d *dbBase) collectValues(mi *modelInfo, ind reflect.Value, cols []string, skipAuto bool, insert bool, names *[]string, tz *time.Location) (values []interface{}, err error) {
 	var columns []string
 
@@ -87,6 +90,7 @@ func (d *dbBase) collectValues(mi *modelInfo, ind reflect.Value, cols []string,
 	return
 }
 
+// get one field value in struct column as interface.
 func (d *dbBase) collectFieldValue(mi *modelInfo, fi *fieldInfo, ind reflect.Value, insert bool, tz *time.Location) (interface{}, error) {
 	var value interface{}
 	if fi.pk {
@@ -155,6 +159,7 @@ func (d *dbBase) collectFieldValue(mi *modelInfo, fi *fieldInfo, ind reflect.Val
 	return value, nil
 }
 
+// create insert sql preparation statement object.
 func (d *dbBase) PrepareInsert(q dbQuerier, mi *modelInfo) (stmtQuerier, string, error) {
 	Q := d.ins.TableQuote()
 
@@ -180,6 +185,7 @@ func (d *dbBase) PrepareInsert(q dbQuerier, mi *modelInfo) (stmtQuerier, string,
 	return stmt, query, err
 }
 
+// insert struct with prepared statement and given struct reflect value.
 func (d *dbBase) InsertStmt(stmt stmtQuerier, mi *modelInfo, ind reflect.Value, tz *time.Location) (int64, error) {
 	values, err := d.collectValues(mi, ind, mi.fields.dbcols, true, true, nil, tz)
 	if err != nil {
@@ -200,6 +206,7 @@ func (d *dbBase) InsertStmt(stmt stmtQuerier, mi *modelInfo, ind reflect.Value,
 	}
 }
 
+// query sql ,read records and persist in dbBaser.
 func (d *dbBase) Read(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.Location, cols []string) error {
 	var whereCols []string
 	var args []interface{}
@@ -259,6 +266,7 @@ func (d *dbBase) Read(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.Lo
 	return nil
 }
 
+// execute insert sql dbQuerier with given struct reflect.Value.
 func (d *dbBase) Insert(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.Location) (int64, error) {
 	names := make([]string, 0, len(mi.fields.dbcols)-1)
 	values, err := d.collectValues(mi, ind, mi.fields.dbcols, true, true, &names, tz)
@@ -269,6 +277,7 @@ func (d *dbBase) Insert(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.
 	return d.InsertValue(q, mi, false, names, values)
 }
 
+// multi-insert sql with given slice struct reflect.Value.
 func (d *dbBase) InsertMulti(q dbQuerier, mi *modelInfo, sind reflect.Value, bulk int, tz *time.Location) (int64, error) {
 	var (
 		cnt    int64
@@ -325,6 +334,8 @@ func (d *dbBase) InsertMulti(q dbQuerier, mi *modelInfo, sind reflect.Value, bul
 	return cnt, nil
 }
 
+// execute insert sql with given struct and given values.
+// insert the given values, not the field values in struct.
 func (d *dbBase) InsertValue(q dbQuerier, mi *modelInfo, isMulti bool, names []string, values []interface{}) (int64, error) {
 	Q := d.ins.TableQuote()
 
@@ -364,6 +375,7 @@ func (d *dbBase) InsertValue(q dbQuerier, mi *modelInfo, isMulti bool, names []s
 	}
 }
 
+// execute update sql dbQuerier with given struct reflect.Value.
 func (d *dbBase) Update(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.Location, cols []string) (int64, error) {
 	pkName, pkValue, ok := getExistPk(mi, ind)
 	if ok == false {
@@ -404,6 +416,8 @@ func (d *dbBase) Update(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.
 	return 0, nil
 }
 
+// execute delete sql dbQuerier with given struct reflect.Value.
+// delete index is pk.
 func (d *dbBase) Delete(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.Location) (int64, error) {
 	pkName, pkValue, ok := getExistPk(mi, ind)
 	if ok == false {
@@ -445,6 +459,8 @@ func (d *dbBase) Delete(q dbQuerier, mi *modelInfo, ind reflect.Value, tz *time.
 	return 0, nil
 }
 
+// update table-related record by querySet.
+// need querySet not struct reflect.Value to update related records.
 func (d *dbBase) UpdateBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condition, params Params, tz *time.Location) (int64, error) {
 	columns := make([]string, 0, len(params))
 	values := make([]interface{}, 0, len(params))
@@ -520,6 +536,8 @@ func (d *dbBase) UpdateBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Con
 	return 0, nil
 }
 
+// delete related records.
+// do UpdateBanch or DeleteBanch by condition of tables' relationship.
 func (d *dbBase) deleteRels(q dbQuerier, mi *modelInfo, args []interface{}, tz *time.Location) error {
 	for _, fi := range mi.fields.fieldsReverse {
 		fi = fi.reverseFieldInfo
@@ -546,6 +564,7 @@ func (d *dbBase) deleteRels(q dbQuerier, mi *modelInfo, args []interface{}, tz *
 	return nil
 }
 
+// delete table-related records.
 func (d *dbBase) DeleteBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condition, tz *time.Location) (int64, error) {
 	tables := newDbTables(mi, d.ins)
 	tables.skipEnd = true
@@ -623,6 +642,7 @@ func (d *dbBase) DeleteBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Con
 	return 0, nil
 }
 
+// read related records.
 func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condition, container interface{}, tz *time.Location, cols []string) (int64, error) {
 
 	val := reflect.ValueOf(container)
@@ -832,6 +852,7 @@ func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condi
 	return cnt, nil
 }
 
+// excute count sql and return count result int64.
 func (d *dbBase) Count(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condition, tz *time.Location) (cnt int64, err error) {
 	tables := newDbTables(mi, d.ins)
 	tables.parseRelated(qs.related, qs.relDepth)
@@ -852,6 +873,7 @@ func (d *dbBase) Count(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condition
 	return
 }
 
+// generate sql with replacing operator string placeholders and replaced values.
 func (d *dbBase) GenerateOperatorSql(mi *modelInfo, fi *fieldInfo, operator string, args []interface{}, tz *time.Location) (string, []interface{}) {
 	sql := ""
 	params := getFlatParams(fi, args, tz)
@@ -905,10 +927,12 @@ func (d *dbBase) GenerateOperatorSql(mi *modelInfo, fi *fieldInfo, operator stri
 	return sql, params
 }
 
+// gernerate sql string with inner function, such as UPPER(text).
 func (d *dbBase) GenerateOperatorLeftCol(*fieldInfo, string, *string) {
 	// default not use
 }
 
+// set values to struct column.
 func (d *dbBase) setColsValues(mi *modelInfo, ind *reflect.Value, cols []string, values []interface{}, tz *time.Location) {
 	for i, column := range cols {
 		val := reflect.Indirect(reflect.ValueOf(values[i])).Interface()
@@ -930,6 +954,7 @@ func (d *dbBase) setColsValues(mi *modelInfo, ind *reflect.Value, cols []string,
 	}
 }
 
+// convert value from database result to value following in field type.
 func (d *dbBase) convertValueFromDB(fi *fieldInfo, val interface{}, tz *time.Location) (interface{}, error) {
 	if val == nil {
 		return nil, nil
@@ -1082,6 +1107,7 @@ end:
 
 }
 
+// set one value to struct column field.
 func (d *dbBase) setFieldValue(fi *fieldInfo, value interface{}, field reflect.Value) (interface{}, error) {
 
 	fieldType := fi.fieldType
@@ -1156,6 +1182,7 @@ setValue:
 	return value, nil
 }
 
+// query sql, read values , save to *[]ParamList.
 func (d *dbBase) ReadValues(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condition, exprs []string, container interface{}, tz *time.Location) (int64, error) {
 
 	var (
@@ -1323,6 +1350,7 @@ func (d *dbBase) ReadValues(q dbQuerier, qs *querySet, mi *modelInfo, cond *Cond
 	return cnt, nil
 }
 
+// flag of update joined record.
 func (d *dbBase) SupportUpdateJoin() bool {
 	return true
 }
@@ -1331,30 +1359,37 @@ func (d *dbBase) MaxLimit() uint64 {
 	return 18446744073709551615
 }
 
+// return quote.
 func (d *dbBase) TableQuote() string {
 	return "`"
 }
 
+// replace value placeholer in parametered sql string.
 func (d *dbBase) ReplaceMarks(query *string) {
 	// default use `?` as mark, do nothing
 }
 
+// flag of RETURNING sql.
 func (d *dbBase) HasReturningID(*modelInfo, *string) bool {
 	return false
 }
 
+// convert time from db.
 func (d *dbBase) TimeFromDB(t *time.Time, tz *time.Location) {
 	*t = t.In(tz)
 }
 
+// convert time to db.
 func (d *dbBase) TimeToDB(t *time.Time, tz *time.Location) {
 	*t = t.In(tz)
 }
 
+// get database types.
 func (d *dbBase) DbTypes() map[string]string {
 	return nil
 }
 
+// gt all tables.
 func (d *dbBase) GetTables(db dbQuerier) (map[string]bool, error) {
 	tables := make(map[string]bool)
 	query := d.ins.ShowTablesQuery()
@@ -1379,6 +1414,7 @@ func (d *dbBase) GetTables(db dbQuerier) (map[string]bool, error) {
 	return tables, nil
 }
 
+// get all cloumns in table.
 func (d *dbBase) GetColumns(db dbQuerier, table string) (map[string][3]string, error) {
 	columns := make(map[string][3]string)
 	query := d.ins.ShowColumnsQuery(table)
@@ -1405,18 +1441,22 @@ func (d *dbBase) GetColumns(db dbQuerier, table string) (map[string][3]string, e
 	return columns, nil
 }
 
+// not implement.
 func (d *dbBase) OperatorSql(operator string) string {
 	panic(ErrNotImplement)
 }
 
+// not implement.
 func (d *dbBase) ShowTablesQuery() string {
 	panic(ErrNotImplement)
 }
 
+// not implement.
 func (d *dbBase) ShowColumnsQuery(table string) string {
 	panic(ErrNotImplement)
 }
 
+// not implement.
 func (d *dbBase) IndexExists(dbQuerier, string, string) bool {
 	panic(ErrNotImplement)
 }
diff --git a/orm/db_alias.go b/orm/db_alias.go
index 24924312..d50b6ebd 100644
--- a/orm/db_alias.go
+++ b/orm/db_alias.go
@@ -9,27 +9,32 @@ import (
 	"time"
 )
 
+// database driver constant int.
 type DriverType int
 
 const (
-	_ DriverType = iota
-	DR_MySQL
-	DR_Sqlite
-	DR_Oracle
-	DR_Postgres
+	_ DriverType = iota // int enum type
+	DR_MySQL // mysql
+	DR_Sqlite // sqlite
+	DR_Oracle // oracle
+	DR_Postgres // pgsql
 )
 
+// database driver string.
 type driver string
 
+// get type constant int of current driver..
 func (d driver) Type() DriverType {
 	a, _ := dataBaseCache.get(string(d))
 	return a.Driver
 }
 
+// get name of current driver
 func (d driver) Name() string {
 	return string(d)
 }
 
+// check driver iis implemented Driver interface or not.
 var _ Driver = new(driver)
 
 var (
@@ -47,11 +52,13 @@ var (
 	}
 )
 
+// database alias cacher.
 type _dbCache struct {
 	mux   sync.RWMutex
 	cache map[string]*alias
 }
 
+// add database alias with original name.
 func (ac *_dbCache) add(name string, al *alias) (added bool) {
 	ac.mux.Lock()
 	defer ac.mux.Unlock()
@@ -62,6 +69,7 @@ func (ac *_dbCache) add(name string, al *alias) (added bool) {
 	return
 }
 
+// get database alias if cached.
 func (ac *_dbCache) get(name string) (al *alias, ok bool) {
 	ac.mux.RLock()
 	defer ac.mux.RUnlock()
@@ -69,6 +77,7 @@ func (ac *_dbCache) get(name string) (al *alias, ok bool) {
 	return
 }
 
+// get default alias.
 func (ac *_dbCache) getDefault() (al *alias) {
 	al, _ = ac.get("default")
 	return
diff --git a/orm/db_mysql.go b/orm/db_mysql.go
index da123079..566f2992 100644
--- a/orm/db_mysql.go
+++ b/orm/db_mysql.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 )
 
+// mysql operators.
 var mysqlOperators = map[string]string{
 	"exact":     "= ?",
 	"iexact":    "LIKE ?",
@@ -21,6 +22,7 @@ var mysqlOperators = map[string]string{
 	"iendswith":   "LIKE ?",
 }
 
+// mysql column field types.
 var mysqlTypes = map[string]string{
 	"auto":            "AUTO_INCREMENT NOT NULL PRIMARY KEY",
 	"pk":              "NOT NULL PRIMARY KEY",
@@ -41,29 +43,35 @@ var mysqlTypes = map[string]string{
 	"float64-decimal": "numeric(%d, %d)",
 }
 
+// mysql dbBaser implementation.
 type dbBaseMysql struct {
 	dbBase
 }
 
 var _ dbBaser = new(dbBaseMysql)
 
+// get mysql operator.
 func (d *dbBaseMysql) OperatorSql(operator string) string {
 	return mysqlOperators[operator]
 }
 
+// get mysql table field types.
 func (d *dbBaseMysql) DbTypes() map[string]string {
 	return mysqlTypes
 }
 
+// show table sql for mysql.
 func (d *dbBaseMysql) ShowTablesQuery() string {
 	return "SELECT table_name FROM information_schema.tables WHERE table_type = 'BASE TABLE' AND table_schema = DATABASE()"
 }
 
+// show columns sql of table for mysql.
 func (d *dbBaseMysql) ShowColumnsQuery(table string) string {
 	return fmt.Sprintf("SELECT COLUMN_NAME, COLUMN_TYPE, IS_NULLABLE FROM information_schema.columns "+
 		"WHERE table_schema = DATABASE() AND table_name = '%s'", table)
 }
 
+// execute sql to check index exist.
 func (d *dbBaseMysql) IndexExists(db dbQuerier, table string, name string) bool {
 	row := db.QueryRow("SELECT count(*) FROM information_schema.statistics "+
 		"WHERE table_schema = DATABASE() AND table_name = ? AND index_name = ?", table, name)
@@ -72,6 +80,7 @@ func (d *dbBaseMysql) IndexExists(db dbQuerier, table string, name string) bool
 	return cnt > 0
 }
 
+// create new mysql dbBaser.
 func newdbBaseMysql() dbBaser {
 	b := new(dbBaseMysql)
 	b.ins = b
diff --git a/orm/db_oracle.go b/orm/db_oracle.go
index ca1715ef..8e374122 100644
--- a/orm/db_oracle.go
+++ b/orm/db_oracle.go
@@ -1,11 +1,13 @@
 package orm
 
+// oracle dbBaser
 type dbBaseOracle struct {
 	dbBase
 }
 
 var _ dbBaser = new(dbBaseOracle)
 
+// create oracle dbBaser.
 func newdbBaseOracle() dbBaser {
 	b := new(dbBaseOracle)
 	b.ins = b
diff --git a/orm/db_postgres.go b/orm/db_postgres.go
index 4058fc10..d26511c0 100644
--- a/orm/db_postgres.go
+++ b/orm/db_postgres.go
@@ -5,6 +5,7 @@ import (
 	"strconv"
 )
 
+// postgresql operators.
 var postgresOperators = map[string]string{
 	"exact":       "= ?",
 	"iexact":      "= UPPER(?)",
@@ -20,6 +21,7 @@ var postgresOperators = map[string]string{
 	"iendswith":   "LIKE UPPER(?)",
 }
 
+// postgresql column field types.
 var postgresTypes = map[string]string{
 	"auto":            "serial NOT NULL PRIMARY KEY",
 	"pk":              "NOT NULL PRIMARY KEY",
@@ -40,16 +42,19 @@ var postgresTypes = map[string]string{
 	"float64-decimal": "numeric(%d, %d)",
 }
 
+// postgresql dbBaser.
 type dbBasePostgres struct {
 	dbBase
 }
 
 var _ dbBaser = new(dbBasePostgres)
 
+// get postgresql operator.
 func (d *dbBasePostgres) OperatorSql(operator string) string {
 	return postgresOperators[operator]
 }
 
+// generate functioned sql string, such as contains(text).
 func (d *dbBasePostgres) GenerateOperatorLeftCol(fi *fieldInfo, operator string, leftCol *string) {
 	switch operator {
 	case "contains", "startswith", "endswith":
@@ -59,6 +64,7 @@ func (d *dbBasePostgres) GenerateOperatorLeftCol(fi *fieldInfo, operator string,
 	}
 }
 
+// postgresql unsupports updating joined record.
 func (d *dbBasePostgres) SupportUpdateJoin() bool {
 	return false
 }
@@ -67,10 +73,13 @@ func (d *dbBasePostgres) MaxLimit() uint64 {
 	return 0
 }
 
+// postgresql quote is ".
 func (d *dbBasePostgres) TableQuote() string {
 	return `"`
 }
 
+// postgresql value placeholder is $n.
+// replace default ? to $n.
 func (d *dbBasePostgres) ReplaceMarks(query *string) {
 	q := *query
 	num := 0
@@ -97,6 +106,7 @@ func (d *dbBasePostgres) ReplaceMarks(query *string) {
 	*query = string(data)
 }
 
+// make returning sql support for postgresql.
 func (d *dbBasePostgres) HasReturningID(mi *modelInfo, query *string) (has bool) {
 	if mi.fields.pk.auto {
 		if query != nil {
@@ -107,18 +117,22 @@ func (d *dbBasePostgres) HasReturningID(mi *modelInfo, query *string) (has bool)
 	return
 }
 
+// show table sql for postgresql.
 func (d *dbBasePostgres) ShowTablesQuery() string {
 	return "SELECT table_name FROM information_schema.tables WHERE table_type = 'BASE TABLE' AND table_schema NOT IN ('pg_catalog', 'information_schema')"
 }
 
+// show table columns sql for postgresql.
 func (d *dbBasePostgres) ShowColumnsQuery(table string) string {
 	return fmt.Sprintf("SELECT column_name, data_type, is_nullable FROM information_schema.columns where table_schema NOT IN ('pg_catalog', 'information_schema') and table_name = '%s'", table)
 }
 
+// get column types of postgresql.
 func (d *dbBasePostgres) DbTypes() map[string]string {
 	return postgresTypes
 }
 
+// check index exist in postgresql.
 func (d *dbBasePostgres) IndexExists(db dbQuerier, table string, name string) bool {
 	query := fmt.Sprintf("SELECT COUNT(*) FROM pg_indexes WHERE tablename = '%s' AND indexname = '%s'", table, name)
 	row := db.QueryRow(query)
@@ -127,6 +141,7 @@ func (d *dbBasePostgres) IndexExists(db dbQuerier, table string, name string) bo
 	return cnt > 0
 }
 
+// create new postgresql dbBaser.
 func newdbBasePostgres() dbBaser {
 	b := new(dbBasePostgres)
 	b.ins = b
diff --git a/orm/db_sqlite.go b/orm/db_sqlite.go
index 7711ded0..81692e2c 100644
--- a/orm/db_sqlite.go
+++ b/orm/db_sqlite.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 )
 
+// sqlite operators.
 var sqliteOperators = map[string]string{
 	"exact":       "= ?",
 	"iexact":      "LIKE ? ESCAPE '\\'",
@@ -20,6 +21,7 @@ var sqliteOperators = map[string]string{
 	"iendswith":   "LIKE ? ESCAPE '\\'",
 }
 
+// sqlite column types.
 var sqliteTypes = map[string]string{
 	"auto":            "integer NOT NULL PRIMARY KEY AUTOINCREMENT",
 	"pk":              "NOT NULL PRIMARY KEY",
@@ -40,38 +42,47 @@ var sqliteTypes = map[string]string{
 	"float64-decimal": "decimal",
 }
 
+// sqlite dbBaser.
 type dbBaseSqlite struct {
 	dbBase
 }
 
 var _ dbBaser = new(dbBaseSqlite)
 
+// get sqlite operator.
 func (d *dbBaseSqlite) OperatorSql(operator string) string {
 	return sqliteOperators[operator]
 }
 
+// generate functioned sql for sqlite.
+// only support DATE(text).
 func (d *dbBaseSqlite) GenerateOperatorLeftCol(fi *fieldInfo, operator string, leftCol *string) {
 	if fi.fieldType == TypeDateField {
 		*leftCol = fmt.Sprintf("DATE(%s)", *leftCol)
 	}
 }
 
+// unable updating joined record in sqlite.
 func (d *dbBaseSqlite) SupportUpdateJoin() bool {
 	return false
 }
 
+// max int in sqlite.
 func (d *dbBaseSqlite) MaxLimit() uint64 {
 	return 9223372036854775807
 }
 
+// get column types in sqlite.
 func (d *dbBaseSqlite) DbTypes() map[string]string {
 	return sqliteTypes
 }
 
+// get show tables sql in sqlite.
 func (d *dbBaseSqlite) ShowTablesQuery() string {
 	return "SELECT name FROM sqlite_master WHERE type = 'table'"
 }
 
+// get columns in sqlite.
 func (d *dbBaseSqlite) GetColumns(db dbQuerier, table string) (map[string][3]string, error) {
 	query := d.ins.ShowColumnsQuery(table)
 	rows, err := db.Query(query)
@@ -92,10 +103,12 @@ func (d *dbBaseSqlite) GetColumns(db dbQuerier, table string) (map[string][3]str
 	return columns, nil
 }
 
+// get show columns sql in sqlite.
 func (d *dbBaseSqlite) ShowColumnsQuery(table string) string {
 	return fmt.Sprintf("pragma table_info('%s')", table)
 }
 
+// check index exist in sqlite.
 func (d *dbBaseSqlite) IndexExists(db dbQuerier, table string, name string) bool {
 	query := fmt.Sprintf("PRAGMA index_list('%s')", table)
 	rows, err := db.Query(query)
@@ -113,6 +126,7 @@ func (d *dbBaseSqlite) IndexExists(db dbQuerier, table string, name string) bool
 	return false
 }
 
+// create new sqlite dbBaser.
 func newdbBaseSqlite() dbBaser {
 	b := new(dbBaseSqlite)
 	b.ins = b
diff --git a/orm/db_tables.go b/orm/db_tables.go
index f5cacf38..854c4214 100644
--- a/orm/db_tables.go
+++ b/orm/db_tables.go
@@ -6,6 +6,7 @@ import (
 	"time"
 )
 
+// table info struct.
 type dbTable struct {
 	id    int
 	index string
@@ -18,6 +19,7 @@ type dbTable struct {
 	jtl   *dbTable
 }
 
+// tables collection struct, contains some tables.
 type dbTables struct {
 	tablesM map[string]*dbTable
 	tables  []*dbTable
@@ -26,6 +28,8 @@ type dbTables struct {
 	skipEnd bool
 }
 
+// set table info to collection.
+// if not exist, create new.
 func (t *dbTables) set(names []string, mi *modelInfo, fi *fieldInfo, inner bool) *dbTable {
 	name := strings.Join(names, ExprSep)
 	if j, ok := t.tablesM[name]; ok {
@@ -42,6 +46,7 @@ func (t *dbTables) set(names []string, mi *modelInfo, fi *fieldInfo, inner bool)
 	return t.tablesM[name]
 }
 
+// add table info to collection.
 func (t *dbTables) add(names []string, mi *modelInfo, fi *fieldInfo, inner bool) (*dbTable, bool) {
 	name := strings.Join(names, ExprSep)
 	if _, ok := t.tablesM[name]; ok == false {
@@ -54,11 +59,14 @@ func (t *dbTables) add(names []string, mi *modelInfo, fi *fieldInfo, inner bool)
 	return t.tablesM[name], false
 }
 
+// get table info in collection.
 func (t *dbTables) get(name string) (*dbTable, bool) {
 	j, ok := t.tablesM[name]
 	return j, ok
 }
 
+// get related fields info in recursive depth loop.
+// loop once, depth decreases one.
 func (t *dbTables) loopDepth(depth int, prefix string, fi *fieldInfo, related []string) []string {
 	if depth < 0 || fi.fieldType == RelManyToMany {
 		return related
@@ -79,6 +87,7 @@ func (t *dbTables) loopDepth(depth int, prefix string, fi *fieldInfo, related []
 	return related
 }
 
+// parse related fields.
 func (t *dbTables) parseRelated(rels []string, depth int) {
 
 	relsNum := len(rels)
@@ -140,6 +149,7 @@ func (t *dbTables) parseRelated(rels []string, depth int) {
 	}
 }
 
+// generate join string.
 func (t *dbTables) getJoinSql() (join string) {
 	Q := t.base.TableQuote()
 
@@ -186,6 +196,7 @@ func (t *dbTables) getJoinSql() (join string) {
 	return
 }
 
+// parse orm model struct field tag expression.
 func (t *dbTables) parseExprs(mi *modelInfo, exprs []string) (index, name string, info *fieldInfo, success bool) {
 	var (
 		jtl *dbTable
@@ -300,6 +311,7 @@ loopFor:
 	return
 }
 
+// generate condition sql.
 func (t *dbTables) getCondSql(cond *Condition, sub bool, tz *time.Location) (where string, params []interface{}) {
 	if cond == nil || cond.IsEmpty() {
 		return
@@ -364,6 +376,7 @@ func (t *dbTables) getCondSql(cond *Condition, sub bool, tz *time.Location) (whe
 	return
 }
 
+// generate order sql.
 func (t *dbTables) getOrderSql(orders []string) (orderSql string) {
 	if len(orders) == 0 {
 		return
@@ -392,6 +405,7 @@ func (t *dbTables) getOrderSql(orders []string) (orderSql string) {
 	return
 }
 
+// generate limit sql.
 func (t *dbTables) getLimitSql(mi *modelInfo, offset int64, limit int64) (limits string) {
 	if limit == 0 {
 		limit = int64(DefaultRowsLimit)
@@ -414,6 +428,7 @@ func (t *dbTables) getLimitSql(mi *modelInfo, offset int64, limit int64) (limits
 	return
 }
 
+// crete new tables collection.
 func newDbTables(mi *modelInfo, base dbBaser) *dbTables {
 	tables := &dbTables{}
 	tables.tablesM = make(map[string]*dbTable)
diff --git a/orm/db_utils.go b/orm/db_utils.go
index e2178294..34de8186 100644
--- a/orm/db_utils.go
+++ b/orm/db_utils.go
@@ -6,6 +6,7 @@ import (
 	"time"
 )
 
+// get table alias.
 func getDbAlias(name string) *alias {
 	if al, ok := dataBaseCache.get(name); ok {
 		return al
@@ -15,6 +16,7 @@ func getDbAlias(name string) *alias {
 	return nil
 }
 
+// get pk column info.
 func getExistPk(mi *modelInfo, ind reflect.Value) (column string, value interface{}, exist bool) {
 	fi := mi.fields.pk
 
@@ -37,6 +39,7 @@ func getExistPk(mi *modelInfo, ind reflect.Value) (column string, value interfac
 	return
 }
 
+// get fields description as flatted string.
 func getFlatParams(fi *fieldInfo, args []interface{}, tz *time.Location) (params []interface{}) {
 
 outFor:
diff --git a/orm/models.go b/orm/models.go
index 1cb25c4c..5744d865 100644
--- a/orm/models.go
+++ b/orm/models.go
@@ -41,6 +41,7 @@ var (
 	}
 )
 
+// model info collection
 type _modelCache struct {
 	sync.RWMutex
 	orders    []string
@@ -49,6 +50,7 @@ type _modelCache struct {
 	done      bool
 }
 
+// get all model info
 func (mc *_modelCache) all() map[string]*modelInfo {
 	m := make(map[string]*modelInfo, len(mc.cache))
 	for k, v := range mc.cache {
@@ -57,6 +59,7 @@ func (mc *_modelCache) all() map[string]*modelInfo {
 	return m
 }
 
+// get orderd model info
 func (mc *_modelCache) allOrdered() []*modelInfo {
 	m := make([]*modelInfo, 0, len(mc.orders))
 	for _, table := range mc.orders {
@@ -65,16 +68,19 @@ func (mc *_modelCache) allOrdered() []*modelInfo {
 	return m
 }
 
+// get model info by table name
 func (mc *_modelCache) get(table string) (mi *modelInfo, ok bool) {
 	mi, ok = mc.cache[table]
 	return
 }
 
+// get model info by field name
 func (mc *_modelCache) getByFN(name string) (mi *modelInfo, ok bool) {
 	mi, ok = mc.cacheByFN[name]
 	return
 }
 
+// set model info to collection
 func (mc *_modelCache) set(table string, mi *modelInfo) *modelInfo {
 	mii := mc.cache[table]
 	mc.cache[table] = mi
@@ -85,6 +91,7 @@ func (mc *_modelCache) set(table string, mi *modelInfo) *modelInfo {
 	return mii
 }
 
+// clean all model info.
 func (mc *_modelCache) clean() {
 	mc.orders = make([]string, 0)
 	mc.cache = make(map[string]*modelInfo)
diff --git a/orm/models_boot.go b/orm/models_boot.go
index 3274b187..03caeb62 100644
--- a/orm/models_boot.go
+++ b/orm/models_boot.go
@@ -8,6 +8,8 @@ import (
 	"strings"
 )
 
+// register models.
+// prefix means table name prefix.
 func registerModel(model interface{}, prefix string) {
 	val := reflect.ValueOf(model)
 	ind := reflect.Indirect(val)
@@ -67,6 +69,7 @@ func registerModel(model interface{}, prefix string) {
 	modelCache.set(table, info)
 }
 
+// boostrap models
 func bootStrap() {
 	if modelCache.done {
 		return
@@ -281,6 +284,7 @@ end:
 	}
 }
 
+// register models
 func RegisterModel(models ...interface{}) {
 	if modelCache.done {
 		panic(fmt.Errorf("RegisterModel must be run before BootStrap"))
@@ -302,6 +306,8 @@ func RegisterModelWithPrefix(prefix string, models ...interface{}) {
 	}
 }
 
+// bootrap models.
+// make all model parsed and can not add more models
 func BootStrap() {
 	if modelCache.done {
 		return
diff --git a/orm/models_info_f.go b/orm/models_info_f.go
index 03736091..fadbb335 100644
--- a/orm/models_info_f.go
+++ b/orm/models_info_f.go
@@ -9,6 +9,7 @@ import (
 
 var errSkipField = errors.New("skip field")
 
+// field info collection
 type fields struct {
 	pk            *fieldInfo
 	columns       map[string]*fieldInfo
@@ -23,6 +24,7 @@ type fields struct {
 	dbcols        []string
 }
 
+// add field info
 func (f *fields) Add(fi *fieldInfo) (added bool) {
 	if f.fields[fi.name] == nil && f.columns[fi.column] == nil {
 		f.columns[fi.column] = fi
@@ -49,14 +51,17 @@ func (f *fields) Add(fi *fieldInfo) (added bool) {
 	return true
 }
 
+// get field info by name
 func (f *fields) GetByName(name string) *fieldInfo {
 	return f.fields[name]
 }
 
+// get field info by column name
 func (f *fields) GetByColumn(column string) *fieldInfo {
 	return f.columns[column]
 }
 
+// get field info by string, name is prior
 func (f *fields) GetByAny(name string) (*fieldInfo, bool) {
 	if fi, ok := f.fields[name]; ok {
 		return fi, ok
@@ -70,6 +75,7 @@ func (f *fields) GetByAny(name string) (*fieldInfo, bool) {
 	return nil, false
 }
 
+// create new field info collection
 func newFields() *fields {
 	f := new(fields)
 	f.fields = make(map[string]*fieldInfo)
@@ -79,6 +85,7 @@ func newFields() *fields {
 	return f
 }
 
+// single field info
 type fieldInfo struct {
 	mi                  *modelInfo
 	fieldIndex          int
@@ -115,6 +122,7 @@ type fieldInfo struct {
 	onDelete            string
 }
 
+// new field info
 func newFieldInfo(mi *modelInfo, field reflect.Value, sf reflect.StructField) (fi *fieldInfo, err error) {
 	var (
 		tag       string
diff --git a/orm/models_info_m.go b/orm/models_info_m.go
index 7a173781..b596fc6a 100644
--- a/orm/models_info_m.go
+++ b/orm/models_info_m.go
@@ -7,6 +7,7 @@ import (
 	"reflect"
 )
 
+// single model info
 type modelInfo struct {
 	pkg       string
 	name      string
@@ -20,6 +21,7 @@ type modelInfo struct {
 	isThrough bool
 }
 
+// new model info
 func newModelInfo(val reflect.Value) (info *modelInfo) {
 	var (
 		err error
@@ -79,6 +81,8 @@ func newModelInfo(val reflect.Value) (info *modelInfo) {
 	return
 }
 
+// combine related model info to new model info.
+// prepare for relation models query.
 func newM2MModelInfo(m1, m2 *modelInfo) (info *modelInfo) {
 	info = new(modelInfo)
 	info.fields = newFields()
diff --git a/orm/models_utils.go b/orm/models_utils.go
index 38095b7e..1466a724 100644
--- a/orm/models_utils.go
+++ b/orm/models_utils.go
@@ -7,10 +7,12 @@ import (
 	"time"
 )
 
+// get reflect.Type name with package path.
 func getFullName(typ reflect.Type) string {
 	return typ.PkgPath() + "." + typ.Name()
 }
 
+// get table name. method, or field name. auto snaked.
 func getTableName(val reflect.Value) string {
 	ind := reflect.Indirect(val)
 	fun := val.MethodByName("TableName")
@@ -26,6 +28,7 @@ func getTableName(val reflect.Value) string {
 	return snakeString(ind.Type().Name())
 }
 
+// get table engine, mysiam or innodb.
 func getTableEngine(val reflect.Value) string {
 	fun := val.MethodByName("TableEngine")
 	if fun.IsValid() {
@@ -40,6 +43,7 @@ func getTableEngine(val reflect.Value) string {
 	return ""
 }
 
+// get table index from method.
 func getTableIndex(val reflect.Value) [][]string {
 	fun := val.MethodByName("TableIndex")
 	if fun.IsValid() {
@@ -56,6 +60,7 @@ func getTableIndex(val reflect.Value) [][]string {
 	return nil
 }
 
+// get table unique from method
 func getTableUnique(val reflect.Value) [][]string {
 	fun := val.MethodByName("TableUnique")
 	if fun.IsValid() {
@@ -72,6 +77,7 @@ func getTableUnique(val reflect.Value) [][]string {
 	return nil
 }
 
+// get snaked column name
 func getColumnName(ft int, addrField reflect.Value, sf reflect.StructField, col string) string {
 	col = strings.ToLower(col)
 	column := col
@@ -89,6 +95,7 @@ func getColumnName(ft int, addrField reflect.Value, sf reflect.StructField, col
 	return column
 }
 
+// return field type as type constant from reflect.Value
 func getFieldType(val reflect.Value) (ft int, err error) {
 	elm := reflect.Indirect(val)
 	switch elm.Kind() {
@@ -128,6 +135,7 @@ func getFieldType(val reflect.Value) (ft int, err error) {
 	return
 }
 
+// parse struct tag string
 func parseStructTag(data string, attrs *map[string]bool, tags *map[string]string) {
 	attr := make(map[string]bool)
 	tag := make(map[string]string)
diff --git a/orm/orm.go b/orm/orm.go
index 9e3c3565..71b4daa4 100644
--- a/orm/orm.go
+++ b/orm/orm.go
@@ -40,6 +40,7 @@ type orm struct {
 
 var _ Ormer = new(orm)
 
+// get model info and model reflect value
 func (o *orm) getMiInd(md interface{}, needPtr bool) (mi *modelInfo, ind reflect.Value) {
 	val := reflect.ValueOf(md)
 	ind = reflect.Indirect(val)
@@ -54,6 +55,7 @@ func (o *orm) getMiInd(md interface{}, needPtr bool) (mi *modelInfo, ind reflect
 	panic(fmt.Errorf("<Ormer> table: `%s` not found, maybe not RegisterModel", name))
 }
 
+// get field info from model info by given field name
 func (o *orm) getFieldInfo(mi *modelInfo, name string) *fieldInfo {
 	fi, ok := mi.fields.GetByAny(name)
 	if !ok {
@@ -62,6 +64,7 @@ func (o *orm) getFieldInfo(mi *modelInfo, name string) *fieldInfo {
 	return fi
 }
 
+// read data to model
 func (o *orm) Read(md interface{}, cols ...string) error {
 	mi, ind := o.getMiInd(md, true)
 	err := o.alias.DbBaser.Read(o.db, mi, ind, o.alias.TZ, cols)
@@ -71,6 +74,7 @@ func (o *orm) Read(md interface{}, cols ...string) error {
 	return nil
 }
 
+// insert model data to database
 func (o *orm) Insert(md interface{}) (int64, error) {
 	mi, ind := o.getMiInd(md, true)
 	id, err := o.alias.DbBaser.Insert(o.db, mi, ind, o.alias.TZ)
@@ -83,6 +87,7 @@ func (o *orm) Insert(md interface{}) (int64, error) {
 	return id, nil
 }
 
+// set auto pk field
 func (o *orm) setPk(mi *modelInfo, ind reflect.Value, id int64) {
 	if mi.fields.pk.auto {
 		if mi.fields.pk.fieldType&IsPostiveIntegerField > 0 {
@@ -93,6 +98,7 @@ func (o *orm) setPk(mi *modelInfo, ind reflect.Value, id int64) {
 	}
 }
 
+// insert some models to database
 func (o *orm) InsertMulti(bulk int, mds interface{}) (int64, error) {
 	var cnt int64
 
@@ -127,6 +133,8 @@ func (o *orm) InsertMulti(bulk int, mds interface{}) (int64, error) {
 	return cnt, nil
 }
 
+// update model to database.
+// cols set the columns those want to update.
 func (o *orm) Update(md interface{}, cols ...string) (int64, error) {
 	mi, ind := o.getMiInd(md, true)
 	num, err := o.alias.DbBaser.Update(o.db, mi, ind, o.alias.TZ, cols)
@@ -136,6 +144,7 @@ func (o *orm) Update(md interface{}, cols ...string) (int64, error) {
 	return num, nil
 }
 
+// delete model in database
 func (o *orm) Delete(md interface{}) (int64, error) {
 	mi, ind := o.getMiInd(md, true)
 	num, err := o.alias.DbBaser.Delete(o.db, mi, ind, o.alias.TZ)
@@ -148,6 +157,7 @@ func (o *orm) Delete(md interface{}) (int64, error) {
 	return num, nil
 }
 
+// create a models to models queryer
 func (o *orm) QueryM2M(md interface{}, name string) QueryM2Mer {
 	mi, ind := o.getMiInd(md, true)
 	fi := o.getFieldInfo(mi, name)
@@ -162,6 +172,14 @@ func (o *orm) QueryM2M(md interface{}, name string) QueryM2Mer {
 	return newQueryM2M(md, o, mi, fi, ind)
 }
 
+// load related models to md model.
+// args are limit, offset int and order string.
+//
+// example:
+// 	orm.LoadRelated(post,"Tags")
+// 	for _,tag := range post.Tags{...}
+//
+// make sure the relation is defined in model struct tags.
 func (o *orm) LoadRelated(md interface{}, name string, args ...interface{}) (int64, error) {
 	_, fi, ind, qseter := o.queryRelated(md, name)
 
@@ -223,12 +241,19 @@ func (o *orm) LoadRelated(md interface{}, name string, args ...interface{}) (int
 	return nums, err
 }
 
+// return a QuerySeter for related models to md model.
+// it can do all, update, delete in QuerySeter.
+// example:
+// 	qs := orm.QueryRelated(post,"Tag")
+//  qs.All(&[]*Tag{})
+//
 func (o *orm) QueryRelated(md interface{}, name string) QuerySeter {
 	// is this api needed ?
 	_, _, _, qs := o.queryRelated(md, name)
 	return qs
 }
 
+// get QuerySeter for related models to md model
 func (o *orm) queryRelated(md interface{}, name string) (*modelInfo, *fieldInfo, reflect.Value, QuerySeter) {
 	mi, ind := o.getMiInd(md, true)
 	fi := o.getFieldInfo(mi, name)
@@ -260,6 +285,7 @@ func (o *orm) queryRelated(md interface{}, name string) (*modelInfo, *fieldInfo,
 	return mi, fi, ind, qs
 }
 
+// get reverse relation QuerySeter
 func (o *orm) getReverseQs(md interface{}, mi *modelInfo, fi *fieldInfo) *querySet {
 	switch fi.fieldType {
 	case RelReverseOne, RelReverseMany:
@@ -280,6 +306,7 @@ func (o *orm) getReverseQs(md interface{}, mi *modelInfo, fi *fieldInfo) *queryS
 	return q
 }
 
+// get relation QuerySeter
 func (o *orm) getRelQs(md interface{}, mi *modelInfo, fi *fieldInfo) *querySet {
 	switch fi.fieldType {
 	case RelOneToOne, RelForeignKey, RelManyToMany:
@@ -299,6 +326,9 @@ func (o *orm) getRelQs(md interface{}, mi *modelInfo, fi *fieldInfo) *querySet {
 	return q
 }
 
+// return a QuerySeter for table operations.
+// table name can be string or struct.
+// e.g. QueryTable("user"), QueryTable(&user{}) or QueryTable((*User)(nil)),
 func (o *orm) QueryTable(ptrStructOrTableName interface{}) (qs QuerySeter) {
 	name := ""
 	if table, ok := ptrStructOrTableName.(string); ok {
@@ -318,6 +348,7 @@ func (o *orm) QueryTable(ptrStructOrTableName interface{}) (qs QuerySeter) {
 	return
 }
 
+// switch to another registered database driver by given name.
 func (o *orm) Using(name string) error {
 	if o.isTx {
 		panic(fmt.Errorf("<Ormer.Using> transaction has been start, cannot change db"))
@@ -335,6 +366,7 @@ func (o *orm) Using(name string) error {
 	return nil
 }
 
+// begin transaction
 func (o *orm) Begin() error {
 	if o.isTx {
 		return ErrTxHasBegan
@@ -353,6 +385,7 @@ func (o *orm) Begin() error {
 	return nil
 }
 
+// commit transaction
 func (o *orm) Commit() error {
 	if o.isTx == false {
 		return ErrTxDone
@@ -367,6 +400,7 @@ func (o *orm) Commit() error {
 	return err
 }
 
+// rollback transaction
 func (o *orm) Rollback() error {
 	if o.isTx == false {
 		return ErrTxDone
@@ -381,14 +415,17 @@ func (o *orm) Rollback() error {
 	return err
 }
 
+// return a raw query seter for raw sql string.
 func (o *orm) Raw(query string, args ...interface{}) RawSeter {
 	return newRawSet(o, query, args)
 }
 
+// return current using database Driver
 func (o *orm) Driver() Driver {
 	return driver(o.alias.Name)
 }
 
+// create new orm
 func NewOrm() Ormer {
 	BootStrap() // execute only once
 
diff --git a/orm/orm_conds.go b/orm/orm_conds.go
index 91d69986..5b1151e2 100644
--- a/orm/orm_conds.go
+++ b/orm/orm_conds.go
@@ -18,15 +18,19 @@ type condValue struct {
 	isCond bool
 }
 
+// condition struct.
+// work for WHERE conditions.
 type Condition struct {
 	params []condValue
 }
 
+// return new condition struct
 func NewCondition() *Condition {
 	c := &Condition{}
 	return c
 }
 
+// add expression to condition
 func (c Condition) And(expr string, args ...interface{}) *Condition {
 	if expr == "" || len(args) == 0 {
 		panic(fmt.Errorf("<Condition.And> args cannot empty"))
@@ -35,6 +39,7 @@ func (c Condition) And(expr string, args ...interface{}) *Condition {
 	return &c
 }
 
+// add NOT expression to condition
 func (c Condition) AndNot(expr string, args ...interface{}) *Condition {
 	if expr == "" || len(args) == 0 {
 		panic(fmt.Errorf("<Condition.AndNot> args cannot empty"))
@@ -43,6 +48,7 @@ func (c Condition) AndNot(expr string, args ...interface{}) *Condition {
 	return &c
 }
 
+// combine a condition to current condition
 func (c *Condition) AndCond(cond *Condition) *Condition {
 	c = c.clone()
 	if c == cond {
@@ -54,6 +60,7 @@ func (c *Condition) AndCond(cond *Condition) *Condition {
 	return c
 }
 
+// add OR expression to condition
 func (c Condition) Or(expr string, args ...interface{}) *Condition {
 	if expr == "" || len(args) == 0 {
 		panic(fmt.Errorf("<Condition.Or> args cannot empty"))
@@ -62,6 +69,7 @@ func (c Condition) Or(expr string, args ...interface{}) *Condition {
 	return &c
 }
 
+// add OR NOT expression to condition
 func (c Condition) OrNot(expr string, args ...interface{}) *Condition {
 	if expr == "" || len(args) == 0 {
 		panic(fmt.Errorf("<Condition.OrNot> args cannot empty"))
@@ -70,6 +78,7 @@ func (c Condition) OrNot(expr string, args ...interface{}) *Condition {
 	return &c
 }
 
+// combine a OR condition to current condition
 func (c *Condition) OrCond(cond *Condition) *Condition {
 	c = c.clone()
 	if c == cond {
@@ -81,10 +90,12 @@ func (c *Condition) OrCond(cond *Condition) *Condition {
 	return c
 }
 
+// check the condition arguments are empty or not.
 func (c *Condition) IsEmpty() bool {
 	return len(c.params) == 0
 }
 
+// clone a condition
 func (c Condition) clone() *Condition {
 	return &c
 }
diff --git a/orm/orm_log.go b/orm/orm_log.go
index 0bb5d6f9..e6df797a 100644
--- a/orm/orm_log.go
+++ b/orm/orm_log.go
@@ -13,6 +13,7 @@ type Log struct {
 	*log.Logger
 }
 
+// set io.Writer to create a Logger.
 func NewLog(out io.Writer) *Log {
 	d := new(Log)
 	d.Logger = log.New(out, "[ORM]", 1e9)
@@ -40,6 +41,8 @@ func debugLogQueies(alias *alias, operaton, query string, t time.Time, err error
 	DebugLog.Println(con)
 }
 
+// statement query logger struct.
+// if dev mode, use stmtQueryLog, or use stmtQuerier.
 type stmtQueryLog struct {
 	alias *alias
 	query string
@@ -84,6 +87,8 @@ func newStmtQueryLog(alias *alias, stmt stmtQuerier, query string) stmtQuerier {
 	return d
 }
 
+// database query logger struct.
+// if dev mode, use dbQueryLog, or use dbQuerier.
 type dbQueryLog struct {
 	alias *alias
 	db    dbQuerier
diff --git a/orm/orm_object.go b/orm/orm_object.go
index 3c6d1f0e..fa644349 100644
--- a/orm/orm_object.go
+++ b/orm/orm_object.go
@@ -5,6 +5,7 @@ import (
 	"reflect"
 )
 
+// an insert queryer struct
 type insertSet struct {
 	mi     *modelInfo
 	orm    *orm
@@ -14,6 +15,7 @@ type insertSet struct {
 
 var _ Inserter = new(insertSet)
 
+// insert model ignore it's registered or not.
 func (o *insertSet) Insert(md interface{}) (int64, error) {
 	if o.closed {
 		return 0, ErrStmtClosed
@@ -44,6 +46,7 @@ func (o *insertSet) Insert(md interface{}) (int64, error) {
 	return id, nil
 }
 
+// close insert queryer statement
 func (o *insertSet) Close() error {
 	if o.closed {
 		return ErrStmtClosed
@@ -52,6 +55,7 @@ func (o *insertSet) Close() error {
 	return o.stmt.Close()
 }
 
+// create new insert queryer.
 func newInsertSet(orm *orm, mi *modelInfo) (Inserter, error) {
 	bi := new(insertSet)
 	bi.orm = orm
diff --git a/orm/orm_querym2m.go b/orm/orm_querym2m.go
index 6f0544d0..f0bc94b7 100644
--- a/orm/orm_querym2m.go
+++ b/orm/orm_querym2m.go
@@ -4,6 +4,7 @@ import (
 	"reflect"
 )
 
+// model to model struct
 type queryM2M struct {
 	md  interface{}
 	mi  *modelInfo
@@ -12,6 +13,13 @@ type queryM2M struct {
 	ind reflect.Value
 }
 
+// add models to origin models when creating queryM2M.
+// example:
+// 	m2m := orm.QueryM2M(post,"Tag")
+// 	m2m.Add(&Tag1{},&Tag2{})
+//  for _,tag := range post.Tags{}
+//
+// make sure the relation is defined in post model struct tag.
 func (o *queryM2M) Add(mds ...interface{}) (int64, error) {
 	fi := o.fi
 	mi := fi.relThroughModelInfo
@@ -67,6 +75,7 @@ func (o *queryM2M) Add(mds ...interface{}) (int64, error) {
 	return dbase.InsertValue(orm.db, mi, true, names, values)
 }
 
+// remove models following the origin model relationship
 func (o *queryM2M) Remove(mds ...interface{}) (int64, error) {
 	fi := o.fi
 	qs := o.qs.Filter(fi.reverseFieldInfo.name, o.md)
@@ -78,17 +87,20 @@ func (o *queryM2M) Remove(mds ...interface{}) (int64, error) {
 	return nums, nil
 }
 
+// check model is existed in relationship of origin model
 func (o *queryM2M) Exist(md interface{}) bool {
 	fi := o.fi
 	return o.qs.Filter(fi.reverseFieldInfo.name, o.md).
 		Filter(fi.reverseFieldInfoTwo.name, md).Exist()
 }
 
+// clean all models in related of origin model
 func (o *queryM2M) Clear() (int64, error) {
 	fi := o.fi
 	return o.qs.Filter(fi.reverseFieldInfo.name, o.md).Delete()
 }
 
+// count all related models of origin model
 func (o *queryM2M) Count() (int64, error) {
 	fi := o.fi
 	return o.qs.Filter(fi.reverseFieldInfo.name, o.md).Count()
@@ -96,6 +108,7 @@ func (o *queryM2M) Count() (int64, error) {
 
 var _ QueryM2Mer = new(queryM2M)
 
+// create new M2M queryer.
 func newQueryM2M(md interface{}, o *orm, mi *modelInfo, fi *fieldInfo, ind reflect.Value) QueryM2Mer {
 	qm2m := new(queryM2M)
 	qm2m.md = md
diff --git a/orm/orm_queryset.go b/orm/orm_queryset.go
index b25d0542..ad8a9374 100644
--- a/orm/orm_queryset.go
+++ b/orm/orm_queryset.go
@@ -18,6 +18,10 @@ const (
 	Col_Except
 )
 
+// ColValue do the field raw changes. e.g Nums = Nums + 10. usage:
+// 	Params{
+// 		"Nums": ColValue(Col_Add, 10),
+// 	}
 func ColValue(opt operator, value interface{}) interface{} {
 	switch opt {
 	case Col_Add, Col_Minus, Col_Multiply, Col_Except:
@@ -34,6 +38,7 @@ func ColValue(opt operator, value interface{}) interface{} {
 	return val
 }
 
+// real query struct
 type querySet struct {
 	mi       *modelInfo
 	cond     *Condition
@@ -47,6 +52,7 @@ type querySet struct {
 
 var _ QuerySeter = new(querySet)
 
+// add condition expression to QuerySeter.
 func (o querySet) Filter(expr string, args ...interface{}) QuerySeter {
 	if o.cond == nil {
 		o.cond = NewCondition()
@@ -55,6 +61,7 @@ func (o querySet) Filter(expr string, args ...interface{}) QuerySeter {
 	return &o
 }
 
+// add NOT condition to querySeter.
 func (o querySet) Exclude(expr string, args ...interface{}) QuerySeter {
 	if o.cond == nil {
 		o.cond = NewCondition()
@@ -63,10 +70,13 @@ func (o querySet) Exclude(expr string, args ...interface{}) QuerySeter {
 	return &o
 }
 
+// set offset number
 func (o *querySet) setOffset(num interface{}) {
 	o.offset = ToInt64(num)
 }
 
+// add LIMIT value.
+// args[0] means offset, e.g. LIMIT num,offset.
 func (o querySet) Limit(limit interface{}, args ...interface{}) QuerySeter {
 	o.limit = ToInt64(limit)
 	if len(args) > 0 {
@@ -75,16 +85,21 @@ func (o querySet) Limit(limit interface{}, args ...interface{}) QuerySeter {
 	return &o
 }
 
+// add OFFSET value
 func (o querySet) Offset(offset interface{}) QuerySeter {
 	o.setOffset(offset)
 	return &o
 }
 
+// add ORDER expression.
+// "column" means ASC, "-column" means DESC.
 func (o querySet) OrderBy(exprs ...string) QuerySeter {
 	o.orders = exprs
 	return &o
 }
 
+// set relation model to query together.
+// it will query relation models and assign to parent model.
 func (o querySet) RelatedSel(params ...interface{}) QuerySeter {
 	var related []string
 	if len(params) == 0 {
@@ -105,36 +120,50 @@ func (o querySet) RelatedSel(params ...interface{}) QuerySeter {
 	return &o
 }
 
+// set condition to QuerySeter.
 func (o querySet) SetCond(cond *Condition) QuerySeter {
 	o.cond = cond
 	return &o
 }
 
+// return QuerySeter execution result number
 func (o *querySet) Count() (int64, error) {
 	return o.orm.alias.DbBaser.Count(o.orm.db, o, o.mi, o.cond, o.orm.alias.TZ)
 }
 
+// check result empty or not after QuerySeter executed
 func (o *querySet) Exist() bool {
 	cnt, _ := o.orm.alias.DbBaser.Count(o.orm.db, o, o.mi, o.cond, o.orm.alias.TZ)
 	return cnt > 0
 }
 
+// execute update with parameters
 func (o *querySet) Update(values Params) (int64, error) {
 	return o.orm.alias.DbBaser.UpdateBatch(o.orm.db, o, o.mi, o.cond, values, o.orm.alias.TZ)
 }
 
+// execute delete
 func (o *querySet) Delete() (int64, error) {
 	return o.orm.alias.DbBaser.DeleteBatch(o.orm.db, o, o.mi, o.cond, o.orm.alias.TZ)
 }
 
+// return a insert queryer.
+// it can be used in times.
+// example:
+// 	i,err := sq.PrepareInsert()
+// 	i.Add(&user1{},&user2{})
 func (o *querySet) PrepareInsert() (Inserter, error) {
 	return newInsertSet(o.orm, o.mi)
 }
 
+// query all data and map to containers.
+// cols means the columns when querying.
 func (o *querySet) All(container interface{}, cols ...string) (int64, error) {
 	return o.orm.alias.DbBaser.ReadBatch(o.orm.db, o, o.mi, o.cond, container, o.orm.alias.TZ, cols)
 }
 
+// query one row data and map to containers.
+// cols means the columns when querying.
 func (o *querySet) One(container interface{}, cols ...string) error {
 	num, err := o.orm.alias.DbBaser.ReadBatch(o.orm.db, o, o.mi, o.cond, container, o.orm.alias.TZ, cols)
 	if err != nil {
@@ -149,18 +178,26 @@ func (o *querySet) One(container interface{}, cols ...string) error {
 	return nil
 }
 
+// query all data and map to []map[string]interface.
+// expres means condition expression.
+// it converts data to []map[column]value.
 func (o *querySet) Values(results *[]Params, exprs ...string) (int64, error) {
 	return o.orm.alias.DbBaser.ReadValues(o.orm.db, o, o.mi, o.cond, exprs, results, o.orm.alias.TZ)
 }
 
+// query all data and map to [][]interface
+// it converts data to [][column_index]value
 func (o *querySet) ValuesList(results *[]ParamsList, exprs ...string) (int64, error) {
 	return o.orm.alias.DbBaser.ReadValues(o.orm.db, o, o.mi, o.cond, exprs, results, o.orm.alias.TZ)
 }
 
+// query all data and map to []interface.
+// it's designed for one row record set, auto change to []value, not [][column]value.
 func (o *querySet) ValuesFlat(result *ParamsList, expr string) (int64, error) {
 	return o.orm.alias.DbBaser.ReadValues(o.orm.db, o, o.mi, o.cond, []string{expr}, result, o.orm.alias.TZ)
 }
 
+// create new QuerySeter.
 func newQuerySet(orm *orm, mi *modelInfo) QuerySeter {
 	o := new(querySet)
 	o.mi = mi
diff --git a/orm/orm_raw.go b/orm/orm_raw.go
index a713dbac..3f5fb162 100644
--- a/orm/orm_raw.go
+++ b/orm/orm_raw.go
@@ -7,6 +7,7 @@ import (
 	"time"
 )
 
+// raw sql string prepared statement
 type rawPrepare struct {
 	rs     *rawSet
 	stmt   stmtQuerier
@@ -44,6 +45,7 @@ func newRawPreparer(rs *rawSet) (RawPreparer, error) {
 	return o, nil
 }
 
+// raw query seter
 type rawSet struct {
 	query string
 	args  []interface{}
@@ -52,11 +54,13 @@ type rawSet struct {
 
 var _ RawSeter = new(rawSet)
 
+// set args for every query
 func (o rawSet) SetArgs(args ...interface{}) RawSeter {
 	o.args = args
 	return &o
 }
 
+// execute raw sql and return sql.Result
 func (o *rawSet) Exec() (sql.Result, error) {
 	query := o.query
 	o.orm.alias.DbBaser.ReplaceMarks(&query)
@@ -65,6 +69,7 @@ func (o *rawSet) Exec() (sql.Result, error) {
 	return o.orm.db.Exec(query, args...)
 }
 
+// set field value to row container
 func (o *rawSet) setFieldValue(ind reflect.Value, value interface{}) {
 	switch ind.Kind() {
 	case reflect.Bool:
@@ -163,6 +168,7 @@ func (o *rawSet) setFieldValue(ind reflect.Value, value interface{}) {
 	}
 }
 
+// set field value in loop for slice container
 func (o *rawSet) loopSetRefs(refs []interface{}, sInds []reflect.Value, nIndsPtr *[]reflect.Value, eTyps []reflect.Type, init bool) {
 	nInds := *nIndsPtr
 
@@ -233,6 +239,7 @@ func (o *rawSet) loopSetRefs(refs []interface{}, sInds []reflect.Value, nIndsPtr
 	}
 }
 
+// query data and map to container
 func (o *rawSet) QueryRow(containers ...interface{}) error {
 	refs := make([]interface{}, 0, len(containers))
 	sInds := make([]reflect.Value, 0)
@@ -362,6 +369,7 @@ func (o *rawSet) QueryRow(containers ...interface{}) error {
 	return nil
 }
 
+// query data rows and map to container
 func (o *rawSet) QueryRows(containers ...interface{}) (int64, error) {
 	refs := make([]interface{}, 0, len(containers))
 	sInds := make([]reflect.Value, 0)
@@ -615,18 +623,22 @@ func (o *rawSet) readValues(container interface{}) (int64, error) {
 	return cnt, nil
 }
 
+// query data to []map[string]interface
 func (o *rawSet) Values(container *[]Params) (int64, error) {
 	return o.readValues(container)
 }
 
+// query data to [][]interface
 func (o *rawSet) ValuesList(container *[]ParamsList) (int64, error) {
 	return o.readValues(container)
 }
 
+// query data to []interface
 func (o *rawSet) ValuesFlat(container *ParamsList) (int64, error) {
 	return o.readValues(container)
 }
 
+// return prepared raw statement for used in times.
 func (o *rawSet) Prepare() (RawPreparer, error) {
 	return newRawPreparer(o)
 }
diff --git a/orm/types.go b/orm/types.go
index a6487fc0..6f13ed67 100644
--- a/orm/types.go
+++ b/orm/types.go
@@ -6,11 +6,13 @@ import (
 	"time"
 )
 
+// database driver
 type Driver interface {
 	Name() string
 	Type() DriverType
 }
 
+// field info
 type Fielder interface {
 	String() string
 	FieldType() int
@@ -18,6 +20,7 @@ type Fielder interface {
 	RawValue() interface{}
 }
 
+// orm struct
 type Ormer interface {
 	Read(interface{}, ...string) error
 	Insert(interface{}) (int64, error)
@@ -35,11 +38,13 @@ type Ormer interface {
 	Driver() Driver
 }
 
+// insert prepared statement
 type Inserter interface {
 	Insert(interface{}) (int64, error)
 	Close() error
 }
 
+// query seter
 type QuerySeter interface {
 	Filter(string, ...interface{}) QuerySeter
 	Exclude(string, ...interface{}) QuerySeter
@@ -60,6 +65,7 @@ type QuerySeter interface {
 	ValuesFlat(*ParamsList, string) (int64, error)
 }
 
+// model to model query struct
 type QueryM2Mer interface {
 	Add(...interface{}) (int64, error)
 	Remove(...interface{}) (int64, error)
@@ -68,11 +74,13 @@ type QueryM2Mer interface {
 	Count() (int64, error)
 }
 
+// raw query statement
 type RawPreparer interface {
 	Exec(...interface{}) (sql.Result, error)
 	Close() error
 }
 
+// raw query seter
 type RawSeter interface {
 	Exec() (sql.Result, error)
 	QueryRow(...interface{}) error
@@ -84,6 +92,7 @@ type RawSeter interface {
 	Prepare() (RawPreparer, error)
 }
 
+// statement querier
 type stmtQuerier interface {
 	Close() error
 	Exec(args ...interface{}) (sql.Result, error)
@@ -91,6 +100,7 @@ type stmtQuerier interface {
 	QueryRow(args ...interface{}) *sql.Row
 }
 
+// db querier
 type dbQuerier interface {
 	Prepare(query string) (*sql.Stmt, error)
 	Exec(query string, args ...interface{}) (sql.Result, error)
@@ -98,15 +108,18 @@ type dbQuerier interface {
 	QueryRow(query string, args ...interface{}) *sql.Row
 }
 
+// transaction beginner
 type txer interface {
 	Begin() (*sql.Tx, error)
 }
 
+// transaction ending
 type txEnder interface {
 	Commit() error
 	Rollback() error
 }
 
+// base database struct
 type dbBaser interface {
 	Read(dbQuerier, *modelInfo, reflect.Value, *time.Location, []string) error
 	Insert(dbQuerier, *modelInfo, reflect.Value, *time.Location) (int64, error)
diff --git a/orm/utils.go b/orm/utils.go
index 237b3edf..2e347278 100644
--- a/orm/utils.go
+++ b/orm/utils.go
@@ -10,6 +10,7 @@ import (
 
 type StrTo string
 
+// set string
 func (f *StrTo) Set(v string) {
 	if v != "" {
 		*f = StrTo(v)
@@ -18,77 +19,93 @@ func (f *StrTo) Set(v string) {
 	}
 }
 
+// clean string
 func (f *StrTo) Clear() {
 	*f = StrTo(0x1E)
 }
 
+// check string exist
 func (f StrTo) Exist() bool {
 	return string(f) != string(0x1E)
 }
 
+// string to bool
 func (f StrTo) Bool() (bool, error) {
 	return strconv.ParseBool(f.String())
 }
 
+// string to float32
 func (f StrTo) Float32() (float32, error) {
 	v, err := strconv.ParseFloat(f.String(), 32)
 	return float32(v), err
 }
 
+// string to float64
 func (f StrTo) Float64() (float64, error) {
 	return strconv.ParseFloat(f.String(), 64)
 }
 
+// string to int
 func (f StrTo) Int() (int, error) {
 	v, err := strconv.ParseInt(f.String(), 10, 32)
 	return int(v), err
 }
 
+// string to int8
 func (f StrTo) Int8() (int8, error) {
 	v, err := strconv.ParseInt(f.String(), 10, 8)
 	return int8(v), err
 }
 
+// string to int16
 func (f StrTo) Int16() (int16, error) {
 	v, err := strconv.ParseInt(f.String(), 10, 16)
 	return int16(v), err
 }
 
+// string to int32
 func (f StrTo) Int32() (int32, error) {
 	v, err := strconv.ParseInt(f.String(), 10, 32)
 	return int32(v), err
 }
 
+// string to int64
 func (f StrTo) Int64() (int64, error) {
 	v, err := strconv.ParseInt(f.String(), 10, 64)
 	return int64(v), err
 }
 
+// string to uint
 func (f StrTo) Uint() (uint, error) {
 	v, err := strconv.ParseUint(f.String(), 10, 32)
 	return uint(v), err
 }
 
+// string to uint8
 func (f StrTo) Uint8() (uint8, error) {
 	v, err := strconv.ParseUint(f.String(), 10, 8)
 	return uint8(v), err
 }
 
+// string to uint16
 func (f StrTo) Uint16() (uint16, error) {
 	v, err := strconv.ParseUint(f.String(), 10, 16)
 	return uint16(v), err
 }
 
+// string to uint31
 func (f StrTo) Uint32() (uint32, error) {
 	v, err := strconv.ParseUint(f.String(), 10, 32)
 	return uint32(v), err
 }
 
+// string to uint64
 func (f StrTo) Uint64() (uint64, error) {
 	v, err := strconv.ParseUint(f.String(), 10, 64)
 	return uint64(v), err
 }
 
+// string to string
 func (f StrTo) String() string {
 	if f.Exist() {
 		return string(f)
@@ -96,6 +113,7 @@ func (f StrTo) String() string {
 	return ""
 }
 
+// interface to string
 func ToStr(value interface{}, args ...int) (s string) {
 	switch v := value.(type) {
 	case bool:
@@ -134,6 +152,7 @@ func ToStr(value interface{}, args ...int) (s string) {
 	return s
 }
 
+// interface to int64
 func ToInt64(value interface{}) (d int64) {
 	val := reflect.ValueOf(value)
 	switch value.(type) {
@@ -147,6 +166,7 @@ func ToInt64(value interface{}) (d int64) {
 	return
 }
 
+// snake string, XxYy to xx_yy
 func snakeString(s string) string {
 	data := make([]byte, 0, len(s)*2)
 	j := false
@@ -164,6 +184,7 @@ func snakeString(s string) string {
 	return strings.ToLower(string(data[:len(data)]))
 }
 
+// camel string, xx_yy to XxYy
 func camelString(s string) string {
 	data := make([]byte, 0, len(s))
 	j := false
@@ -190,6 +211,7 @@ func camelString(s string) string {
 
 type argString []string
 
+// get string by index from string slice
 func (a argString) Get(i int, args ...string) (r string) {
 	if i >= 0 && i < len(a) {
 		r = a[i]
@@ -201,6 +223,7 @@ func (a argString) Get(i int, args ...string) (r string) {
 
 type argInt []int
 
+// get int by index from int slice
 func (a argInt) Get(i int, args ...int) (r int) {
 	if i >= 0 && i < len(a) {
 		r = a[i]
@@ -213,6 +236,7 @@ func (a argInt) Get(i int, args ...int) (r int) {
 
 type argAny []interface{}
 
+// get interface by index from interface slice
 func (a argAny) Get(i int, args ...interface{}) (r interface{}) {
 	if i >= 0 && i < len(a) {
 		r = a[i]
@@ -223,15 +247,18 @@ func (a argAny) Get(i int, args ...interface{}) (r interface{}) {
 	return
 }
 
+// parse time to string with location
 func timeParse(dateString, format string) (time.Time, error) {
 	tp, err := time.ParseInLocation(format, dateString, DefaultTimeLoc)
 	return tp, err
 }
 
+// format time string
 func timeFormat(t time.Time, format string) string {
 	return t.Format(format)
 }
 
+// get pointer indirect type
 func indirectType(v reflect.Type) reflect.Type {
 	switch v.Kind() {
 	case reflect.Ptr: