Gorm：如何将整数列设置为null，并更新内存中的模型？
问题描述：
As a simple background, I have a table foo, with a nullable int foreign key bar_id. I have a function that removes the bar association from foo, aka set it to NULL.
I have tried everything: I tried using sql.NullInt64 as the column type, and then
foo.BarId.Valid = false // even set Int64 = 0 for good measure
db.Save(&foo) // with LogMode(true)
bar_id was not updated in the UPDATE statement
I tried:
db.Raw("UPDATE foo SET bar_id = NULL WHERE id = ?", foo.ID).Row().Scan(&foo)
The SQL was correct thankfully, but the object is not updated. I don't think my version of gorm has Error either.
I tried changing the type of Foo.BarId to an *int64, and setting the pointer to nil, but the output query didn't change bar_id to NULL.
What do I need to do?
答
I got it. I need to specifically include the column in a Select():
db.Model(&foo).Select("bar_id").Updates(map[string]interface{}{"bar_id": nil})