Fix #1274: Add QuerySeter.Distinct()

orm/db.go

@@ -814,7 +814,11 @@ func (d *dbBase) ReadBatch(q dbQuerier, qs *querySet, mi *modelInfo, cond *Condi
 		}
 	}
 
-	query := fmt.Sprintf("SELECT %s FROM %s%s%s T0 %s%s%s%s", sels, Q, mi.table, Q, join, where, orderBy, limit)
+	sqlSelect := "SELECT"
+	if qs.distinct {
+		sqlSelect += " DISTINCT"
+	}
+	query := fmt.Sprintf("%s %s FROM %s%s%s T0 %s%s%s%s", sqlSelect, sels, Q, mi.table, Q, join, where, orderBy, limit)
 
 	d.ins.ReplaceMarks(&query)
 

orm/orm_queryset.go

@@ -61,6 +61,7 @@ type querySet struct {
 	limit    int64
 	offset   int64
 	orders   []string
+	distinct bool
 	orm      *orm
 }
 
@@ -112,6 +113,12 @@ func (o querySet) OrderBy(exprs ...string) QuerySeter {
 	return &o
 }
 
+// add DISTINCT to SELECT
+func (o querySet) Distinct() QuerySeter {
+	o.distinct = true
+	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 {

orm/types.go

@@ -67,6 +67,7 @@ type QuerySeter interface {
 	Limit(interface{}, ...interface{}) QuerySeter
 	Offset(interface{}) QuerySeter
 	OrderBy(...string) QuerySeter
+	Distinct() QuerySeter
 	RelatedSel(...interface{}) QuerySeter
 	Count() (int64, error)
 	Exist() bool