Test Cases Fail with ForeignKeyViolation Error When Using SQLModel.metadata.create_all but Pass with Current Alembic Migrations

[avirajsingh7]

Describe the bug
When running test cases that create database tables using SQLModel.metadata.create_all(test_engine), the tests fail with a sqlalchemy.exc.IntegrityError due to a foreign key constraint violation.

Additionally, running alembic revision --autogenerate -m "add fk constraints" (without making changes to the models) generates a migration file that modifies foreign key constraints and other schema details. After applying this migration, the test cases still fail with the same foreign key violation error.

ERROR app/tests/api/routes/test_responses.py::test_responses_endpoint_success - sqlalchemy.exc.IntegrityError: (psycopg.errors.ForeignKeyViolation) update or delete on table "organization" violates foreign key constraint "credential_organization_id_fkey" on table "credential"
DETAIL:  Key (id)=(15) is still referenced from table "credential".
[SQL: DELETE FROM organization]

The autogenerated migration file contains the following:

def upgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    op.alter_column('credential', 'credential',
               existing_type=sa.VARCHAR(),
               nullable=True)
    op.drop_constraint('credential_organization_id_fkey', 'credential', type_='foreignkey')
    op.drop_constraint('credential_project_id_fkey', 'credential', type_='foreignkey')
    op.create_foreign_key(None, 'credential', 'organization', ['organization_id'], ['id'])
    op.create_foreign_key(None, 'credential', 'project', ['project_id'], ['id'])
    op.alter_column('openai_assistant', 'instructions',
               existing_type=sa.TEXT(),
               type_=sqlmodel.sql.sqltypes.AutoString(),
               existing_nullable=False)
    op.create_index(op.f('ix_openai_assistant_assistant_id'), 'openai_assistant', ['assistant_id'], unique=True)
    op.drop_constraint('openai_assistant_organization_id_fkey', 'openai_assistant', type_='foreignkey')
    op.drop_constraint('openai_assistant_project_id_fkey', 'openai_assistant', type_='foreignkey')
    op.create_foreign_key(None, 'openai_assistant', 'organization', ['organization_id'], ['id'])
    op.create_foreign_key(None, 'openai_assistant', 'project', ['project_id'], ['id'])
    # ### end Alembic commands ###

def downgrade():
    # ### commands auto generated by Alembic - please adjust! ###
    op.drop_constraint(None, 'openai_assistant', type_='foreignkey')
    op.drop_constraint(None, 'openai_assistant', type_='foreignkey')
    op.create_foreign_key('openai_assistant_project_id_fkey', 'openai_assistant', 'project', ['project_id'], ['id'], ondelete='CASCADE')
    op.create_foreign_key('openai_assistant_organization_id_fkey', 'openai_assistant', 'organization', ['organization_id'], ['id'], ondelete='CASCADE')
    op.drop_index(op.f('ix_openai_assistant_assistant_id'), table_name='openai_assistant')
    op.alter_column('openai_assistant', 'instructions',
               existing_type=sqlmodel.sql.sqltypes.AutoString(),
               type_=sa.TEXT(),
               existing_nullable=False)
    op.drop_constraint(None, 'credential', type_='foreignkey')
    op.drop_constraint(None, 'credential', type_='foreignkey')
    op.create_foreign_key('credential_project_id_fkey', 'credential', 'project', ['project_id'], ['id'], ondelete='SET NULL')
    op.create_foreign_key('credential_organization_id_fkey', 'credential', 'organization', ['organization_id'], ['id'], ondelete='CASCADE')
    op.alter_column('credential', 'credential',
               existing_type=sa.VARCHAR(),
               nullable=False)
    # ### end Alembic commands ###

There appears to be a difference between the current database configuration and the intended configuration, as the foreign key constraint violation occurs with both SQLModel.metadata.create_all and the autogenerated migration, suggesting the current database setup lacks proper ondelete behavior (e.g., CASCADE or SET NULL) for the credential_organization_id_fkey constraint.
Still more investigation is needed.