Make callback type

mongox/query/callbacks.go

@@ -4,4 +4,20 @@ import (
 	"context"
 )
 
-type OnDecode func(ctx context.Context, iter interface{}) (err error)
+type Callback func(ctx context.Context, iter interface{}) (err error)
+type Callbacks []Callback
+
+type OnDecode Callback
+
+// Invoke callbacks sequence
+func (c Callbacks) Invoke(ctx context.Context, iter interface{}) (err error) {
+
+	for _, cb := range c {
+		err = cb(ctx, iter)
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}

mongox/query/compose.go

@@ -129,7 +129,7 @@ func applyCallbacks(q *Query, f interface{}) (ok bool) {
 
 	switch cb := f.(type) {
 	case OnDecode:
-		q.ondecode = append(q.ondecode, cb)
+		q.ondecode = append(q.ondecode, Callback(cb))
 		ok = true
 	}
 

mongox/query/query.go

@@ -11,7 +11,7 @@ type Query struct {
 	sorter    Sorter
 	skipper   Skipper
 	preloader Preloader
-	ondecode  []OnDecode
+	ondecode  Callbacks
 }
 
 // And function pushes the elem query to the $and array of the query
@@ -77,7 +77,7 @@ func (q *Query) Preloader() (ok bool, preloads []string) {
 }
 
 // OnDecode callback is called after the mongo decode function
-func (q *Query) OnDecode() (callbacks []OnDecode) {
+func (q *Query) OnDecode() (callbacks Callbacks) {
 	return q.ondecode
 }