Add callback mechanism and implement on-decode callback

mongox/database/callbacks.go

@@ -0,0 +1,19 @@
+package database
+
+import (
+	"context"
+
+	"github.com/mainnika/mongox-go-driver/v2/mongox/query"
+)
+
+func onDecode(ctx context.Context, iter interface{}, callbacks ...query.OnDecode) (err error) {
+
+	for _, cb := range callbacks {
+		err = cb(ctx, iter)
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}

mongox/database/loadarray.go

@@ -49,14 +49,18 @@ func (d *Database) LoadArray(target interface{}, filters ...interface{}) (err er
 	}
 
 	for i = 0; result.Next(d.Context()); {
+
+		var elem interface{}
+
 		if targetSliceV.Len() == i {
-			elem := reflect.New(targetSliceElemT.Elem())
-			err = result.Decode(elem.Interface())
+			value := reflect.New(targetSliceElemT.Elem())
+			err = result.Decode(value.Interface())
+			elem = value.Interface()
 			if err == nil {
-				targetSliceV = reflect.Append(targetSliceV, elem)
+				targetSliceV = reflect.Append(targetSliceV, value)
 			}
 		} else {
-			elem := targetSliceV.Index(i).Interface()
+			elem = targetSliceV.Index(i).Interface()
 			base.Reset(elem)
 			err = result.Decode(elem)
 		}
@@ -65,6 +69,12 @@ func (d *Database) LoadArray(target interface{}, filters ...interface{}) (err er
 			return
 		}
 
+		err = onDecode(d.ctx, elem, composed.OnDecode()...)
+		if err != nil {
+			_ = result.Close(d.Context())
+			return
+		}
+
 		i++
 	}
 

mongox/database/loadone.go

@@ -35,5 +35,15 @@ func (d *Database) LoadOne(target interface{}, filters ...interface{}) (err erro
 
 	base.Reset(target)
 
-	return result.Decode(target)
+	err = result.Decode(target)
+	if err != nil {
+		return
+	}
+
+	err = onDecode(d.ctx, target, composed.OnDecode()...)
+	if err != nil {
+		return
+	}
+
+	return
 }

mongox/database/loadstream.go

@@ -25,7 +25,7 @@ func (d *Database) LoadStream(target interface{}, filters ...interface{}) (loade
 		return
 	}
 
-	loader = &StreamLoader{cur: cursor, ctx: d.Context(), target: target}
+	loader = &StreamLoader{cur: cursor, ctx: d.Context(), target: target, query: composed}
 
 	return
 }

mongox/database/streamloader.go

@@ -5,11 +5,13 @@ import (
 
 	"github.com/mainnika/mongox-go-driver/v2/mongox"
 	"github.com/mainnika/mongox-go-driver/v2/mongox/base"
+	"github.com/mainnika/mongox-go-driver/v2/mongox/query"
 )
 
 // StreamLoader is a controller for a database cursor
 type StreamLoader struct {
 	cur    *mongox.Cursor
+	query  *query.Query
 	ctx    context.Context
 	target interface{}
 }
@@ -36,6 +38,14 @@ func (l *StreamLoader) Decode() (err error) {
 	base.Reset(l.target)
 
 	err = l.cur.Decode(l.target)
+	if err != nil {
+		return
+	}
+
+	err = onDecode(l.ctx, l.target, l.query.OnDecode()...)
+	if err != nil {
+		return
+	}
 
 	return
 }

mongox/query/callbacks.go

@@ -0,0 +1,7 @@
+package query
+
+import (
+	"context"
+)
+
+type OnDecode func(ctx context.Context, iter interface{}) (err error)

mongox/query/compose.go

@@ -38,6 +38,7 @@ func Push(q *Query, f interface{}) (ok bool) {
 	ok = ok || applySkip(q, f)
 	ok = ok || applyProtection(q, f)
 	ok = ok || applyPreloader(q, f)
+	ok = ok || applyCallbacks(q, f)
 
 	return ok
 }
@@ -123,3 +124,14 @@ func applyPreloader(q *Query, f interface{}) (ok bool) {
 
 	return false
 }
+
+func applyCallbacks(q *Query, f interface{}) (ok bool) {
+
+	switch cb := f.(type) {
+	case OnDecode:
+		q.ondecode = append(q.ondecode, cb)
+		ok = true
+	}
+
+	return
+}

mongox/query/query.go

@@ -11,6 +11,7 @@ type Query struct {
 	sorter    Sorter
 	skipper   Skipper
 	preloader Preloader
+	ondecode  []OnDecode
 }
 
 // And function pushes the elem query to the $and array of the query
@@ -75,6 +76,11 @@ func (q *Query) Preloader() (ok bool, preloads []string) {
 	return
 }
 
+// OnDecode callback is called after the mongo decode function
+func (q *Query) OnDecode() (callbacks []OnDecode) {
+	return q.ondecode
+}
+
 // Empty checks the query for any content
 func (q *Query) Empty() (isEmpty bool) {
 	return len(q.m) == 0