Allow to skip associations when creating join table for many2many, close #3605

callbacks/associations.go

@@ -291,7 +291,9 @@ func SaveAfterAssociations(db *gorm.DB) {
 			}
 
 			if elems.Len() > 0 {
-				db.AddError(db.Session(&gorm.Session{NewDB: true}).Clauses(onConflictOption(db.Statement, rel.FieldSchema, nil)).Create(elems.Interface()).Error)
+				if v, ok := selectColumns[rel.Name+".*"]; !ok || v {
+					db.AddError(db.Session(&gorm.Session{NewDB: true}).Clauses(onConflictOption(db.Statement, rel.FieldSchema, nil)).Create(elems.Interface()).Error)
+				}
 
 				for i := 0; i < elems.Len(); i++ {
 					appendToJoins(objs[i], elems.Index(i))

tests/associations_many2many_test.go

@@ -93,6 +93,28 @@ func TestMany2ManyAssociation(t *testing.T) {
 	AssertAssociationCount(t, user2, "Languages", 0, "after clear")
 }
 
+func TestMany2ManyOmitAssociations(t *testing.T) {
+	var user = *GetUser("many2many_omit_associations", Config{Languages: 2})
+
+	if err := DB.Omit("Languages.*").Create(&user).Error; err == nil {
+		t.Fatalf("should raise error when create users without languages reference")
+	}
+
+	if err := DB.Create(&user.Languages).Error; err != nil {
+		t.Fatalf("no error should happen when create languages, but got %v", err)
+	}
+
+	if err := DB.Omit("Languages.*").Create(&user).Error; err != nil {
+		t.Fatalf("no error should happen when create user when languages exists, but got %v", err)
+	}
+
+	// Find
+	var languages []Language
+	if DB.Model(&user).Association("Languages").Find(&languages); len(languages) != 2 {
+		t.Errorf("languages count should be %v, but got %v", 2, len(languages))
+	}
+}
+
 func TestMany2ManyAssociationForSlice(t *testing.T) {
 	var users = []User{
 		*GetUser("slice-many2many-1", Config{Languages: 2}),