adds ability to reset params after a filter runs

When a filter is run _after_ the router completes, it's input params,
such as `":splat"` will have been overwritten by the filter's router pass.
This commit adds the ability to tell the router to revert to the previous input
params after running a filter.

context/input.go

@@ -301,6 +301,14 @@ func (input *BeegoInput) SetParam(key, val string) {
 	input.pnames = append(input.pnames, key)
 }
 
+// ResetParams clears any of the input's Params
+// This function is used to clear parameters so they may be reset between filter
+// passes.
+func (input *BeegoInput) ResetParams() {
+	input.pnames = input.pnames[:0]
+	input.pvalues = input.pvalues[:0]
+}
+
 // Query returns input data item string by a given string.
 func (input *BeegoInput) Query(key string) string {
 	if val := input.Param(key); val != "" {

filter.go

@@ -27,6 +27,7 @@ type FilterRouter struct {
 	tree           *Tree
 	pattern        string
 	returnOnOutput bool
+	resetParams    bool
 }
 
 // ValidRouter checks if the current request is matched by this filter.

router.go

@@ -406,20 +406,27 @@ func (p *ControllerRegister) AddAutoPrefix(prefix string, c ControllerInterface)
 }
 
 // InsertFilter Add a FilterFunc with pattern rule and action constant.
-// The bool params is for setting the returnOnOutput value (false allows multiple filters to execute)
+// params is for:
+//   1. setting the returnOnOutput value (false allows multiple filters to execute)
+//   2. determining whether or not params need to be reset.
 func (p *ControllerRegister) InsertFilter(pattern string, pos int, filter FilterFunc, params ...bool) error {
-	mr := new(FilterRouter)
-	mr.tree = NewTree()
-	mr.pattern = pattern
-	mr.filterFunc = filter
-	if !BConfig.RouterCaseSensitive {
-		pattern = strings.ToLower(pattern)
+	mr := &FilterRouter{
+		tree:           NewTree(),
+		pattern:        pattern,
+		filterFunc:     filter,
+		returnOnOutput: true,
 	}
-	if len(params) == 0 {
-		mr.returnOnOutput = true
-	} else {
+	if !BConfig.RouterCaseSensitive {
+		mr.pattern = strings.ToLower(pattern)
+	}
+
+	paramsLen := len(params)
+	if paramsLen > 0 {
 		mr.returnOnOutput = params[0]
 	}
+	if paramsLen > 1 {
+		mr.resetParams = params[1]
+	}
 	mr.tree.AddRouter(pattern, true)
 	return p.insertFilterRouter(pos, mr)
 }
@@ -581,12 +588,22 @@ func (p *ControllerRegister) geturl(t *Tree, url, controllName, methodName strin
 }
 
 func (p *ControllerRegister) execFilter(context *beecontext.Context, urlPath string, pos int) (started bool) {
+	var preFilterParams map[string]string
 	for _, filterR := range p.filters[pos] {
 		if filterR.returnOnOutput && context.ResponseWriter.Started {
 			return true
 		}
+		if filterR.resetParams {
+			preFilterParams = context.Input.Params()
+		}
 		if ok := filterR.ValidRouter(urlPath, context); ok {
 			filterR.filterFunc(context)
+			if filterR.resetParams {
+				context.Input.ResetParams()
+				for k, v := range preFilterParams {
+					context.Input.SetParam(k, v)
+				}
+			}
 		}
 		if filterR.returnOnOutput && context.ResponseWriter.Started {
 			return true
@@ -810,7 +827,9 @@ Admin:
 		var devInfo string
 
 		statusCode := context.ResponseWriter.Status
-		if statusCode == 0 { statusCode = 200 }
+		if statusCode == 0 {
+			statusCode = 200
+		}
 
 		iswin := (runtime.GOOS == "windows")
 		statusColor := logs.ColorByStatus(iswin, statusCode)

router_test.go

@@ -420,6 +420,74 @@ func testRequest(method, path string) (*httptest.ResponseRecorder, *http.Request
 	return recorder, request
 }
 
+// Expectation: A Filter with the correct configuration should be created given
+// specific parameters.
+func TestInsertFilter(t *testing.T) {
+	testName := "TestInsertFilter"
+
+	mux := NewControllerRegister()
+	mux.InsertFilter("*", BeforeRouter, func(*context.Context) {})
+	if !mux.filters[BeforeRouter][0].returnOnOutput {
+		t.Errorf(
+			"%s: passing no variadic params should set returnOnOutput to true",
+			testName)
+	}
+	if mux.filters[BeforeRouter][0].resetParams {
+		t.Errorf(
+			"%s: passing no variadic params should set resetParams to false",
+			testName)
+	}
+
+	mux = NewControllerRegister()
+	mux.InsertFilter("*", BeforeRouter, func(*context.Context) {}, false)
+	if mux.filters[BeforeRouter][0].returnOnOutput {
+		t.Errorf(
+			"%s: passing false as 1st variadic param should set returnOnOutput to false",
+			testName)
+	}
+
+	mux = NewControllerRegister()
+	mux.InsertFilter("*", BeforeRouter, func(*context.Context) {}, true, true)
+	if !mux.filters[BeforeRouter][0].resetParams {
+		t.Errorf(
+			"%s: passing true as 2nd variadic param should set resetParams to true",
+			testName)
+	}
+}
+
+// Expectation: the second variadic arg should cause the execution of the filter
+// to preserve the parameters from before its execution.
+func TestParamResetFilter(t *testing.T) {
+	testName := "TestParamResetFilter"
+	route := "/beego/*" // splat
+	path := "/beego/routes/routes"
+
+	mux := NewControllerRegister()
+
+	mux.InsertFilter("*", BeforeExec, beegoResetParams, true, true)
+
+	mux.Get(route, beegoHandleResetParams)
+
+	rw, r := testRequest("GET", path)
+	mux.ServeHTTP(rw, r)
+
+	// The two functions, `beegoResetParams` and `beegoHandleResetParams` add
+	// a response header of `Splat`.  The expectation here is that that Header
+	// value should match what the _request's_ router set, not the filter's.
+
+	headers := rw.HeaderMap
+	if len(headers["Splat"]) != 1 {
+		t.Errorf(
+			"%s: There was an error in the test. Splat param not set in Header",
+			testName)
+	}
+	if headers["Splat"][0] != "routes/routes" {
+		t.Errorf(
+			"%s: expected `:splat` param to be [routes/routes] but it was [%s]",
+			testName, headers["Splat"][0])
+	}
+}
+
 // Execution point: BeforeRouter
 // expectation: only BeforeRouter function is executed, notmatch output as router doesn't handle
 func TestFilterBeforeRouter(t *testing.T) {
@@ -612,3 +680,10 @@ func beegoFinishRouter1(ctx *context.Context) {
 func beegoFinishRouter2(ctx *context.Context) {
 	ctx.WriteString("|FinishRouter2")
 }
+func beegoResetParams(ctx *context.Context) {
+	ctx.ResponseWriter.Header().Set("splat", ctx.Input.Param(":splat"))
+}
+
+func beegoHandleResetParams(ctx *context.Context) {
+	ctx.ResponseWriter.Header().Set("splat", ctx.Input.Param(":splat"))
+}