9 "github.com/gin-gonic/gin"
11 "github.com/vapor/errors"
14 func Middleware(serverInstance interface{}) gin.HandlerFunc {
15 return func(c *gin.Context) {
16 // add Access-Control-Allow-Origin
17 c.Header("Access-Control-Allow-Origin", "*")
18 c.Header("Access-Control-Allow-Headers", "Content-Type")
19 c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS")
20 if c.Request.Method == "OPTIONS" {
21 c.AbortWithStatus(http.StatusOK)
25 c.Set(serverLabel, serverInstance)
30 type handlerFun interface{}
32 func HandlerMiddleware(handleFunc interface{}) func(*gin.Context) {
33 if err := validateFuncType(handleFunc); err != nil {
37 return func(context *gin.Context) {
38 handleRequest(context, handleFunc)
42 func validateFuncType(fun handlerFun) error {
43 ft := reflect.TypeOf(fun)
44 if ft.Kind() != reflect.Func || ft.IsVariadic() {
45 return errors.New("need nonvariadic func in " + ft.String())
48 if ft.NumIn() < 1 || ft.NumIn() > 3 {
49 return errors.New("need one or two or three parameters in " + ft.String())
52 if ft.In(0) != contextType {
53 return errors.New("the first parameter must point of context in " + ft.String())
56 if ft.NumIn() == 2 && ft.In(1).Kind() != reflect.Ptr {
57 return errors.New("the second parameter must point in " + ft.String())
60 if ft.NumIn() == 3 && ft.In(2) != paginationQueryType {
61 return errors.New("the third parameter of pagination must point of paginationQuery in " + ft.String())
64 if ft.NumOut() < 1 || ft.NumOut() > 2 {
65 return errors.New("the size of return value must one or two in " + ft.String())
68 // if has pagination, the first return value must slice or array
69 if ft.NumIn() == 3 && ft.Out(0).Kind() != reflect.Slice && ft.Out(0).Kind() != reflect.Array {
70 return errors.New("the first return value of pagination must slice of array in " + ft.String())
73 if !ft.Out(ft.NumOut() - 1).Implements(errorType) {
74 return errors.New("the last return value must error in " + ft.String())
79 // handleRequest get a handler function to process the request by request url
80 func handleRequest(context *gin.Context, fun handlerFun) {
81 args, err := buildHandleFuncArgs(fun, context)
83 respondErrorResp(context, err)
87 result := callHandleFunc(fun, args...)
88 if err := result[len(result)-1]; err != nil {
89 respondErrorResp(context, err.(error))
93 if exist := processPaginationIfPresent(fun, args, result, context); exist {
98 respondSuccessResp(context, nil)
102 respondSuccessResp(context, result[0])
105 func buildHandleFuncArgs(fun handlerFun, context *gin.Context) ([]interface{}, error) {
106 args := []interface{}{context}
108 req, err := createHandleReqArg(fun, context)
110 return nil, errors.Wrap(err, "createHandleReqArg")
113 if err := checkDisplayOrder(req); err != nil {
118 args = append(args, req)
121 ft := reflect.TypeOf(fun)
123 // no pagination exists
128 query, err := parsePagination(context)
130 return nil, errors.Wrap(err, "ParsePagination")
133 args = append(args, query)
137 func createHandleReqArg(fun handlerFun, context *gin.Context) (interface{}, error) {
138 ft := reflect.TypeOf(fun)
142 argType := ft.In(1).Elem()
144 reqArg := reflect.New(argType).Interface()
145 if err := context.ShouldBindJSON(reqArg); err != nil {
146 return nil, errors.Wrap(err, "bind reqArg")
149 b, err := json.Marshal(reqArg)
151 return nil, errors.Wrap(err, "json marshal")
154 context.Set(reqBodyLabel, string(b))
159 func checkDisplayOrder(req interface{}) error {
164 reqType := reflect.TypeOf(req).Elem()
165 reqVal := reflect.ValueOf(req).Elem()
167 for i := 0; i < reqType.NumField(); i++ {
168 field := reqType.Field(i)
169 if field.Type != reflect.TypeOf(Display{}) {
172 display := reqVal.Field(i).Interface().(Display)
174 order := strings.Trim(display.Sorter.Order, "")
175 if order != "desc" && order != "asc" {
176 reqVal.Field(i).Set(reflect.ValueOf(Display{Filter: display.Filter, Sorter: Sorter{By: display.Sorter.By, Order: "desc"}}))
182 func callHandleFunc(fun handlerFun, args ...interface{}) []interface{} {
183 fv := reflect.ValueOf(fun)
185 params := make([]reflect.Value, len(args))
186 for i, arg := range args {
187 params[i] = reflect.ValueOf(arg)
190 rs := fv.Call(params)
191 result := make([]interface{}, len(rs))
192 for i, r := range rs {
193 result[i] = r.Interface()