Fix primary key in embedded struct

embedded_struct_test.go

@@ -35,4 +35,8 @@ func TestSaveAndQueryEmbeddedStruct(t *testing.T) {
 	} else if egNews.BasePost.Title != "engadget_news" {
 		t.Errorf("embedded struct's value should be scanned correctly")
 	}
+
+	if DB.NewScope(&HNPost{}).PrimaryKeyField() == nil {
+		t.Errorf("primary key with embedded struct should works")
+	}
 }

model_struct.go

@@ -233,6 +233,9 @@ func (scope *Scope) GetModelStruct(noRelationship ...bool) *ModelStruct {
 							f = f.clone()
 							f.Names = append([]string{fieldStruct.Name}, f.Names...)
 							modelStruct.StructFields = append(modelStruct.StructFields, f)
+							if f.IsPrimaryKey {
+								modelStruct.PrimaryKeyField = f
+							}
 						}
 						break
 					} else {