Cannot drop index needed in a foreign key constraint

[Lumabots]

After doing this change, the migration works:

from tortoise import BaseDBAsyncClient

RUN_IN_TRANSACTION = True


async def upgrade(db: BaseDBAsyncClient) -> str:
    return """
        ALTER TABLE `tagdata` DROP INDEX `uid_tagdata_guild_i_6441d7`;
        ALTER TABLE `tagdata` ADD UNIQUE INDEX `uid_tagdata_guild_i_41971f` (`guild_id`, `name`);"""


async def downgrade(db: BaseDBAsyncClient) -> str:
    return """
        ALTER TABLE `tagdata` DROP INDEX `uid_tagdata_guild_i_41971f`;
        ALTER TABLE `tagdata` ADD UNIQUE INDEX `uid_tagdata_guild_i_6441d7` (`guild_id`, `user_id`);"""

however when trying to to upgrade it it raise:

  File "/Users/luma/Code/Lumabot-Alpha/.venv/lib/python3.11/site-packages/aerich/cli.py", line 149, in upgrade
    migrated = await command.upgrade(run_in_transaction=in_transaction, fake=fake)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/luma/Code/Lumabot-Alpha/.venv/lib/python3.11/site-packages/aerich/__init__.py", line 137, in upgrade
    await self._upgrade(conn, version_file, fake, version_module)
  File "/Users/luma/Code/Lumabot-Alpha/.venv/lib/python3.11/site-packages/aerich/__init__.py", line 115, in _upgrade
    await conn.execute_script(await upgrade(conn))
  File "/Users/luma/Code/Lumabot-Alpha/.venv/lib/python3.11/site-packages/tortoise/backends/mysql/client.py", line 58, in translate_exceptions_
    raise OperationalError(exc)
tortoise.exceptions.OperationalError: (1553, "Cannot drop index 'uid_tagdata_guild_i_6441d7': needed in a foreign key constraint")

[Lumabots]

i dont know if its related on the fact that i format the name wrong by using text field and not charfield
but if its the case the error should be

tortoise.exceptions.OperationalError: (1005, 'Can\'t create table `s3_Lumabot_test`.`tagdata` (errno: 150 "Foreign key constraint is incorrectly formed")')

and not the other one

[waketzheng]

BTW: Do not use unique_together with a TextField, use a CharField instead.

[waketzheng]

i dont know if its related on the fact that i format the name wrong by using text field and not charfield but if its the case the error should be

tortoise.exceptions.OperationalError: (1005, 'Can\'t create table `s3_Lumabot_test`.`tagdata` (errno: 150 "Foreign key constraint is incorrectly formed")')

and not the other one

You can use the TagGuild class instead of "models.TagGuild", if you are using tortoise-orm>=1.1, for example:

from __future__ import annotations

from datetime import datetime

from tortoise import Model, fields


class TagGuild(Model):
    name = fields.CharField(max_length=20)


class TagData(Model):
    guild: fields.Field[TagGuild] = fields.ForeignKeyField(
        TagGuild,
        related_name="tags",
        on_delete=fields.CASCADE,
    )
    # name: fields.Field[str] = fields.TextField()
    name = fields.CharField(max_length=20)
    user_id: fields.Field[int] = fields.BigIntField()
    message: fields.Field[str] | None = fields.TextField(null=True)
    embed: fields.Field[EmbedType] | None = fields.JSONField(null=True)
    created_at: fields.Field[datetime] = fields.DatetimeField(auto_now_add=True)

    class Meta(Model.Meta):
        # unique_together = ("guild", "user_id")
        unique_together = ("guild", "name")