Allow unlimited CharField for SQLite backend

[Kar Petrosyan]

Model validation throws an error on CharField when the max_length argument is not specified.

class MyModel(models.Model):
    name = models.CharField()

The developer who knows that SQLite can store unlimited characters would be surprised in such cases.
I suggest allowing unlimited characters for SQLite, like we do for PostgreSQL.

Relevant PostgreSQL ticket: https://code.djangoproject.com/ticket/14094

[Mariusz Felisiak]

SQLite has limited number of datatypes, and there is no difference between TEXT and VARCHAR (no declared max length), both would be stored in the TEXT datatype. You can use TextField for unlimited CharField.

[Kar Petrosyan]

Replying to Mariusz Felisiak:

SQLite has limited number of datatypes, and there is no difference between TEXT and VARCHAR (no declared max length), both would be stored in the TEXT datatype. You can use TextField for unlimited CharField.

Does it really solve the problem? I want to use CharField and not TextField (when using sqlite3 for the startup but planning to migrate to another DBMS).
In such cases, I can use CharField (max_length = 1), but it wouldn't make any sense for the reviewer.

[Mariusz Felisiak]

Replying to karosis88:

Does it really solve the problem?

Yes.

I want to use CharField and not TextField (when using sqlite3 for the startup but planning to migrate to another DBMS).
In such cases, I can use CharField (max_length = 1), but it wouldn't make any sense for the reviewer.

There is no way to switch between databases without changing anything. It's recommended to use the same database in development and production environments, unless you're aware of all migration caveats. We accepted #14094, because CharField and TextField use different datatypes on PostgreSQL.

[Simon Charette]

For the record I've opted into accepting this feature in ticket:35759#comment:6 as to me the situation on SQLite is similar to Postgres.

On SQLite both varchar and text are an alias for the same internal type but it's also the case on Postgres where ​they are aliases for varlena.

The lack of constraint enforcement on SQLite is a distinct problem (see #21471) that allowing max_length=None could help solving by providing a way to restore the previous behaviour for users that need it.

[Sarah Boyce]

#35759 was a duplicate - reopening and accepting

[Sarah Boyce]

​PR

[Sarah Boyce <42296566+sarahboyce@…>]

In fd92f24:

Fixed #34887 -- Added support for unlimited models.CharField on SQLite.

Signed-off-by: saJaeHyukc <wogur981208@…>