feat: support custom formvalue function

server.go

@@ -1108,6 +1108,12 @@ func SaveMultipartFile(fh *multipart.FileHeader, path string) (err error) {
 //
 // The returned value is valid until your request handler returns.
 func (ctx *RequestCtx) FormValue(key string) []byte {
+	return defaultFormValue(ctx, key)
+}
+
+type FormValueFunc func(*RequestCtx, string) []byte
+
+var defaultFormValue = func(ctx *RequestCtx, key string) []byte {
 	v := ctx.QueryArgs().Peek(key)
 	if len(v) > 0 {
 		return v
@@ -1126,6 +1132,34 @@ func (ctx *RequestCtx) FormValue(key string) []byte {
 	return nil
 }
 
+// SetCustomFormValueFunc sets FormValue function implementation to get form value.
+func SetCustomFormValueFunc(f FormValueFunc) {
+	defaultFormValue = f
+}
+
+// SetNetHttpFormValueFunc sets FormValue function implementation to get form value.
+// Consistent behaviour with net/http. POST and PUT body parameters take precedence over URL query string values.
+func SetNetHttpFormValueFunc() {
+	SetCustomFormValueFunc(func(ctx *RequestCtx, key string) []byte {
+		v := ctx.PostArgs().Peek(key)
+		if len(v) > 0 {
+			return v
+		}
+		mf, err := ctx.MultipartForm()
+		if err == nil && mf.Value != nil {
+			vv := mf.Value[key]
+			if len(vv) > 0 {
+				return []byte(vv[0])
+			}
+		}
+		v = ctx.QueryArgs().Peek(key)
+		if len(v) > 0 {
+			return v
+		}
+		return nil
+	})
+}
+
 // IsGet returns true if request method is GET.
 func (ctx *RequestCtx) IsGet() bool {
 	return ctx.Request.Header.IsGet()

server_test.go

@@ -1713,6 +1713,22 @@ func TestRequestCtxFormValue(t *testing.T) {
 	}
 }
 
+func TestSetStandardFormValueFunc(t *testing.T) {
+	t.Parallel()
+	SetNetHttpFormValueFunc()
+	var ctx RequestCtx
+	var req Request
+	req.SetRequestURI("/foo/bar?aaa=bbb")
+	req.SetBodyString("aaa=port")
+	req.Header.SetContentType("application/x-www-form-urlencoded")
+
+	ctx.Init(&req, nil, nil)
+
+	v := ctx.FormValue("aaa")
+	if string(v) != "port" {
+		t.Fatalf("unexpected value %q. Expecting %q", v, "port")
+	}
+}
 func TestRequestCtxUserValue(t *testing.T) {
 	t.Parallel()