SQL Errors on migrate a fresh install

Issue summary

SQL Error when trying to migrate django.db.utils.OperationalError: near ")": syntax error

How to reproduce?

Freshly installed a wagtail project trying to isolate the issue. Followed the install instructions then tried to migrate

Technical details

• python3, django 3.0, wagtail 2.9

[jkevingutierrez]

There are a some things that I found, that could be useful:

1. When I ran python manage.py makemigrations it generates something like this:

operations = [
       migrations.RemoveField(
            model_name='homepage',
            name='page_ptr',
        ),
        migrations.AddField(
            model_name='homepage',
            name='translatablepage_ptr',
            field=models.OneToOneField(auto_created=True, default='ptr', on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='wagtailtrans.TranslatablePage'),
            preserve_default=False,
        ),
]

The order here seems to be important, and it should be:

operations = [
      migrations.AddField(
            model_name='homepage',
            name='translatablepage_ptr',
            field=models.OneToOneField(auto_created=True, default='ptr', on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='wagtailtrans.TranslatablePage'),
            preserve_default=False,
        ),
      migrations.RemoveField(
            model_name='homepage',
            name='page_ptr',
        ),     
]

1. After changing the order I was getting a different error:

django.db.utils.IntegrityError: NOT NULL constraint failed: new__home_homepage.page_ptr_id

But after checking the migration guide, I saw that you need to add some manual queries, like:

operations = [
        migrations.RunSQL(
            """
            BEGIN;

            -- Remove constraints so we can edit our table
            ALTER TABLE pages_homepage DROP CONSTRAINT pages_homepage_pkey CASCADE;

            -- Add ``translatablepage_ptr_id`` field and copy the ``page_ptr_id`` content
            ALTER TABLE pages_homepage ADD COLUMN translatablepage_ptr_id INTEGER UNIQUE;
            UPDATE pages_homepage SET translatablepage_ptr_id=page_ptr_id;

            -- Insert the required values in ``wagtailtrans`` table
            INSERT INTO wagtailtrans_language (code, is_default, position, live) SELECT 'en', 't', 0, 't' WHERE NOT EXISTS (SELECT code FROM wagtailtrans_language WHERE code='en');
            INSERT INTO wagtailtrans_translatablepage (translatable_page_ptr_id, canonical_page_id, language_id) SELECT translatablepage_ptr_id, NULL, 1 FROM pages_homepage;

            -- Add required indexes and constraints
            ALTER TABLE pages_homepage ADD CONSTRAINT pages_homepage_translatablepage_ptr_id_e5b77cf7_fk_wagtailtrans_translatable_page_id FOREIGN KEY (translatablepage_ptr_id) REFERENCES wagtailtrans_translatablepage (translatable_page_ptr_id) DEFERRABLE INITIALLY DEFERRED;
            ALTER TABLE pages_homepage ALTER COLUMN translatablepage_ptr_id SET NOT NULL;
            ALTER TABLE pages_homepage ADD PRIMARY KEY (translatablepage_ptr_id);

            -- Remove old page_ptr column
            ALTER TABLE pages_homepage DROP COLUMN IF EXISTS page_ptr_id;

            COMMIT;
            """,
            state_operations=[
                migrations.AddField(
                    model_name='homepage',
                    name='translatablepage_ptr',
                    field=models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='wagtailtrans.TranslatablePage'),
                    preserve_default=False,
                ),
                migrations.RemoveField(
                    model_name='homepage',
                    name='page_ptr',
                ),
            ]
        ),
    ]

1. After replacing my migration file, I was getting another error

django.db.utils.OperationalError: cannot start a transaction within a transaction

To fix this, I removed the BEGIN; and the COMMIT; lines in the query

1. After removing BEGIN; and COMMIT; I was getting a different error:

django.db.utils.OperationalError: near "DROP": syntax error

As per https://stackoverflow.com/a/1884893/4508187 it seems that sqlite doesn’t support alter table drop constraint

It would be good to have some documentation about how to make this work on sqlite, or if not possible, to specify that sqlite can’t be used in the example provided

[jkevingutierrez]

Hi,

I agree with @sarensabertooth, it would be good to have an easier way to implement wagtailtrans, or maybe more guidance on the documentation

I was trying to add this package to a fresh Wagtail installation, but I got that SQL error. django.db.utils.OperationalError: near ")": syntax error

If this is something complex to add to a fresh Wagtail site, I can’t imagine how it would be to add it to a complex site.