sea_orm_migration::schema::timestamp_null Invalid default value in mysql

[laojianzi]

sea-orm/sea-orm-migration/src/schema.rs

Line 320 in 987cb38

pub fn timestamp_null<T: IntoIden>(col: T) -> ColumnDef {

timestamp_null looks like it's telling me to declare that NULL is allowed, whereas the SQL provided by sea-orm doesn't have NULL and doesn't have NOT NULL, and leaves it up to the default behavior of the database's type.

When I tested MySQL 5.7, the database returned an error:

`column_name` timestamp -- ERROR: Invalid default value for 'column_name'

---

Using null solves the problem, but I think most people assume that timestamp_null already includes this behavior

timestamp_null(Users::ColumnAt).null()

So when the semantics of timestamp_null is null, should we show that declaring the field is allowed to be NULL instead of leaving it to the default behavior of the database?

`column_name` timestamp NULL

[tyt2y3]

I agree with you. It would be better to add a NULL explicitly. Although is there a case where the default behavior is not NULL?

[laojianzi]

Yes. we can represent the default database behavior in other ways, such as type_default(), since the current type() will use not_null()

sea-orm/sea-orm-migration/src/schema.rs

Lines 316 to 318 in 987cb38

	pub fn timestamp<T: IntoIden>(col: T) -> ColumnDef {
	timestamp_null(col).not_null().take()
	}

[billy1624]

Hey @laojianzi, thanks for the report! I believe this is a special case for MySQL 5.7, https://dba.stackexchange.com/a/314900.

However, it's always good to have a explicit NULL for nullable column. Please check the PR:

• Migration schema nullable column set null explicitly #2255