Usage🔗

This library is meant for situations where you need to do some special handling whenever data is returned though the Django ORM. Some possible use cases might be:

Audit logging
Obfuscation
Checking permissions
Validating
Enhancing

You might have been considering Django's pre_init or post_init signals, but realized that they do not work when using .values() or .values_list(). Signals can also be hard to maintain and can be overridden on accident.

This isn't to say that using the post-fetch hooks offered by this library are strictly better. For instance, it does not fire on queryset.iterator() due to implementation details, so it that's a requirement, signals might be a better alternative.

If you're interested, here is what you would implement the hooks on your models:

from typing import Any
from post_fetch_hook.models import PostFetchModel

class MyModel(PostFetchModel):

    # You can implement any of these methods.
    # These are their default configurations.

    @classmethod
    def post_fetch_hook(cls, model: "MyModel") -> "MyModel":
        # Special handling
        return model

    @classmethod
    def post_fetch_values_hook(cls, values: dict[str, Any], fields: tuple[str, ...]) -> dict[str, Any]:
        # Special handling
        return values

    @classmethod
    def post_fetch_values_list_hook(cls, values: tuple[Any, ...], fields: tuple[str, ...]) -> tuple[Any, ...]:
        # Special handling
        return values

    @classmethod
    def post_fetch_values_list_flat_hook(cls, value: Any, field: str) -> Any:
        # Special handling
        return value

You can also use the included mixins (PostFetchQuerySetMixin and PostFetchModelMixin) to build the functionality in your custom models.

When using custom models, remember to set base_manager_name = "objects" (given that "objects" points to the manager with the post fetch functionality) in the model Meta-class so that post fetch hooks are fired on related entities.