Partition table with foreign key as key problems

[slapshin]

Hi! Thank you for the useful tool!
I have some problems/questions about generating migration for partitioned models.

For example we have model:

class MyModel(PostgresPartitionedModel):
    class PartitioningMeta:
        method = PostgresPartitioningMethod.RANGE
        key = ["foreign_field"]

    title = models.CharField(...)
    foreign_field = models.ForeignKey(...)

migration looks like:

    operations = [
         psqlextra.backend.migrations.operations.create_partitioned_model.PostgresCreatePartitionedModel(...),
         psqlextra.backend.migrations.operations.add_default_partition.PostgresAddDefaultPartition(...),
         migrations.AddField(
            model_name='MyModel',
            name='foreign_field',
        ),

So, firstly table with "simple" fields is created and after that foreign field will be added to the table. But if this field is used as a partition key we will have the error:
"Model 'MyModel' is not properly configured to be partitioned. Field 'foreign_field' in partitioning key ['foreign_field'] is not a valid field on 'MyModel'". Because the model doesn't "see" this field on executing the PostgresCreatePartitionedModel operation. Why relations are adding after table creation? Maybe it is better to combine this?

[opqpop]

bump, was anyone able to find a workaround for this? I ended duplicating my foreign key columns but was hoping to find a better solution

[davmlaw]

Create the migration, then manually move the FK creation line to above the partitioning_options

Created with pgmakemigrations

        psqlextra.backend.migrations.operations.create_partitioned_model.PostgresCreatePartitionedModel(
            name='MyModel',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('title', models.CharField()),
                # Needs to go here
            ],
            partitioning_options={
                'method': psqlextra.types.PostgresPartitioningMethod['LIST'],
                'key': ['foreign_field'],
            },
        # Skipped
        ),
        # Need to move this into fields above partitioning options
        migrations.AddField(
            model_name='mymodel',
            name='foreign_field',
            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='+', to='foreign_model'),
        ),

Manually Modified

        psqlextra.backend.migrations.operations.create_partitioned_model.PostgresCreatePartitionedModel(
            name='MyModel',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('title', models.CharField()),
                ('foreign_field', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='+', to='foreign_model')),
            ],
            partitioning_options={
                'method': psqlextra.types.PostgresPartitioningMethod['LIST'],
                'key': ['foreign_field'],
            },
        # Skipped
        ),

[Anexen]

It looks like this is Django "feature".
I think Django excludes Foreign keys from the CreateModel operation if the model referenced by the key is created in the same migration. Django cannot be sure that the referenced model is created earlier than the model with the foreign key.

[Photonios]

I think this has been solved in v2.0.4rc1 as a result of PR #150. Please give it a shot :)