Migrations crash on constraints/indexes with CompositePrimaryKey in fields.

[Mariusz Felisiak]

I've created a sample project that tries to add UniqueConstraint with a CompositePrimaryKey in fields. Unfortunately, it crashes when trying to migrate:

  ...
  File "/django/db/backends/base/schema.py", line 509, in create_model
    sql, params = self.table_sql(model)
                  ^^^^^^^^^^^^^^^^^^^^^
  File "/django/db/backends/base/schema.py", line 283, in table_sql
    constraint_sqls.extend(
  File "/django/db/backends/base/schema.py", line 284, in <genexpr>
    constraint.constraint_sql(model, self)
  File "/django/db/models/constraints.py", line 512, in constraint_sql
    return schema_editor._unique_sql(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/django/db/backends/base/schema.py", line 1839, in _unique_sql
    "columns": ", ".join([self.quote_name(field.column) for field in fields]),
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/django/db/backends/base/schema.py", line 207, in quote_name
    return self.connection.ops.quote_name(name)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/django/db/backends/postgresql/operations.py", line 190, in quote_name
    if name.startswith('"') and name.endswith('"'):
       ^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'startswith'

It's similar to the #35992 but fix is in a completely different place so I decided to create a separate ticket.

Bug in 978aae4334fa71ba78a3e94408f0f3aebde8d07c

[Natalia Bidart]

Thank you Mariusz!!!

[Mariusz Felisiak]

​PR

[Sarah Boyce <42296566+sarahboyce@…>]

In 2249370c:

Fixed #35992, Fixed #35997 -- Added system check for CompositePrimaryKeys in Meta.indexes/constraints/unique_together.

CompositePrimaryKeys are not supported in any of these options.