INTPYTHON-698 Allow defining embedded model indexes on the top-level model

[WaVEV]

Index are defined with __ for EMF

class Address(EmbeddedModel):
    unique_constraint_one = models.CharField(max_length=10)
    
    class Meta:
        app_label = "schema_"

class Author(EmbeddedModel):
    address = EmbeddedModelField(Address)
    unique_constraint_two = models.CharField(max_length=10)

    class Meta:
        app_label = "schema_"

class Book(models.Model):
    author = EmbeddedModelField(Author)

    class Meta:
        app_label = "schema_"
        constraints = [
            models.UniqueConstraint(
                fields=["author.unique_constraint_two"],
                name="unique_two",
            ),
            models.UniqueConstraint(
                fields=["author.address.unique_constraint_one"],
                name="unique_one",
            ),
        ]

[timgraham]

I would think this is unnecessary since the Index/Constraint would have to be removed from the model's Meta.indexes/constraints before removing the field.

[WaVEV]

🤔 Oki, I will try to move the logic into _remove_model_indexes and _remove_field_unique. The downfall is I have to pass all the indexes from its parents. Like concatenating all way down the recursion. The index could have been created in anywhere of the hierarchy.

[timgraham]

I think it's simpler than you describe. Example:

class Book(models.Model):
    author = EmbeddedModelField(Author)

    class Meta:
        app_label = "schema_"
        indexes = [
            models.Index(fields=["author__indexed_two"]),
            models.Index(fields=["author__address__indexed_one"]),
        ]

I removing the an index, the generated migration operation is:

migrations.RemoveIndex(
    model_name='book',
    name='embed_index_author._f84329_idx',
),

The logic you describe isn't needed.

[timgraham]

Monkey patching at such a low level seems risky, though I haven't much about what could go wrong. Instead I imagined an Index subclass with this sort of logic. Did you consider it?

[WaVEV]

🤔 Maybe is feasible if we create something like EMFIndex. I didn't considered yet. I could take a look.

[WaVEV]

mmh this way (monkey patching) will not work, I forgot that foreign field, lookups and many other things use this. So isn't very straightforward. I have to think another way to solve this