Use the only field type elem to check the content

go.mod

@@ -5,7 +5,7 @@ go 1.13
 require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.1
-	github.com/stretchr/testify v1.6.1
+	github.com/stretchr/testify v1.7.0
 	github.com/valyala/bytebufferpool v1.0.0
-	go.mongodb.org/mongo-driver v1.4.3
+	go.mongodb.org/mongo-driver v1.4.6
 )

go.sum

@@ -75,11 +75,13 @@ github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6Mwd
 github.com/spf13/cobra v0.0.3/go.mod h1:1l0Ry5zgKvJasoi3XT1TypsSe7PqH0Sj9dhYf7v3XqQ=
 github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.1.1 h1:2vfRuCMp5sSVIDSqO8oNnWJq7mPa6KVP3iPIwFBuy8A=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
-github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/tidwall/pretty v1.0.0 h1:HsD+QiTn7sK6flMKIvNmpqz1qrpP3Ps6jOKIKMooyg4=
 github.com/tidwall/pretty v1.0.0/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
@@ -88,8 +90,8 @@ github.com/xdg/scram v0.0.0-20180814205039-7eeb5667e42c h1:u40Z8hqBAAQyv+vATcGgV
 github.com/xdg/scram v0.0.0-20180814205039-7eeb5667e42c/go.mod h1:lB8K/P019DLNhemzwFU4jHLhdvlE6uDZjXFejJXr49I=
 github.com/xdg/stringprep v0.0.0-20180714160509-73f8eece6fdc h1:n+nNi93yXLkJvKwXNP9d55HC7lGK4H/SRcwB5IaUZLo=
 github.com/xdg/stringprep v0.0.0-20180714160509-73f8eece6fdc/go.mod h1:Jhud4/sHMO4oL310DaZAKk9ZaJ08SJfe+sJh0HrGL1Y=
-go.mongodb.org/mongo-driver v1.4.3 h1:moga+uhicpVshTyaqY9L23E6QqwcHRUv1sqyOsoyOO8=
-go.mongodb.org/mongo-driver v1.4.3/go.mod h1:WcMNYLx/IlOxLe6JRJiv2uXuCz6zBLndR4SoGjYphSc=
+go.mongodb.org/mongo-driver v1.4.6 h1:rh7GdYmDrb8AQSkF8yteAus8qYOgOASWDOv1BWqBXkU=
+go.mongodb.org/mongo-driver v1.4.6/go.mod h1:WcMNYLx/IlOxLe6JRJiv2uXuCz6zBLndR4SoGjYphSc=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190422162423-af44ce270edf/go.mod h1:WFFai1msRO1wXaEeE5yQxYXgSfI8pQAWXbQop6sCtWE=

mongox/database/database.go

@@ -126,8 +126,12 @@ func (d *Database) createAggregateLoad(target interface{}, composed *query.Query
 		pipeline = append(pipeline, primitive.M{"$limit": *composed.Limiter()})
 	}
 
-	el := reflect.ValueOf(target).Elem()
+	el := reflect.ValueOf(target)
 	elType := el.Type()
+	if elType.Kind() == reflect.Ptr {
+		elType = elType.Elem()
+	}
+
 	numField := elType.NumField()
 	preloads, _ := composed.Preloader()
 
@@ -191,17 +195,20 @@ func (d *Database) createAggregateLoad(target interface{}, composed *query.Query
 				continue
 			}
 
-			isSlice := el.Field(i).Kind() == reflect.Slice
+			field := elType.Field(i)
+			fieldType := field.Type
 
-			typ := el.Field(i).Type()
-			if typ.Kind() == reflect.Slice {
-				typ = typ.Elem()
+			isSlice := fieldType.Kind() == reflect.Slice
+			if isSlice {
+				fieldType = fieldType.Elem()
 			}
-			if typ.Kind() != reflect.Ptr {
+
+			isPtr := fieldType.Kind() != reflect.Ptr
+			if isPtr {
 				panic(fmt.Errorf("preload field should have ptr type"))
 			}
 
-			lookupCollection := d.GetCollectionOf(reflect.Zero(typ).Interface())
+			lookupCollection := d.GetCollectionOf(reflect.Zero(fieldType).Interface())
 			lookupVars := primitive.M{"selector": "$" + localField}
 			lookupPipeline := primitive.A{
 				primitive.M{"$match": primitive.M{"$expr": primitive.M{"$eq": primitive.A{"$" + foreignField, "$$selector"}}}},

mongox/database/loadstream.go

@@ -30,7 +30,7 @@ func (d *Database) LoadStream(target interface{}, filters ...interface{}) (loade
 		return
 	}
 
-	loader = &StreamLoader{cur: cursor, ctx: ctx, ref: target, query: composed}
+	loader = &StreamLoader{cur: cursor, ctx: ctx, query: composed}
 
 	return
 }

mongox/database/streamloader.go

@@ -13,7 +13,6 @@ type StreamLoader struct {
 	cur   *mongox.Cursor
 	query *query.Query
 	ctx   context.Context
-	ref   interface{}
 }
 
 // DecodeNextMsg decodes the next document to an interface or returns an error
@@ -80,7 +79,7 @@ func (l *StreamLoader) Cursor() (cursor *mongox.Cursor) {
 func (l *StreamLoader) Close() (err error) {
 
 	closerr := l.cur.Close(l.ctx)
-	invokerr := l.query.OnClose().Invoke(l.ctx, l.ref)
+	invokerr := l.query.OnClose().Invoke(l.ctx, nil)
 
 	if closerr != nil {
 		err = closerr