create-prefetch-post-feed-related-objects-hook.md

create_prefetch_post_feed_related_objects_hook

This hook wraps the standard function Misago uses to create a PrefetchPostFeedRelatedObjects object, which is used to prefetch related objects for items displayed in a posts feed.

The object itself does not implement prefetch logic but instead maintains a list of prefetch operations to be executed in order to fetch the objects from the database.

Additional prefetch operations can be added using the add, add_after and add_before methods.

Location

This hook can be imported from misago.threads.hooks:

from misago.threads.hooks import create_prefetch_post_feed_related_objects_hook

Filter

def custom_create_prefetch_post_feed_related_objects_filter(
    action: CreatePrefetchPostFeedRelatedObjectsHookAction,
    settings: DynamicSettings,
    permissions: UserPermissionsProxy,
    posts: Iterable[Post],
    *,
    categories: Iterable[Category] | None=None,
    threads: Iterable[Thread] | None=None,
    thread_updates: Iterable[ThreadUpdate] | None=None,
    attachments: Iterable[Attachment] | None=None,
    users: Iterable['User'] | None=None,
) -> 'PrefetchPostFeedRelatedObjects':
    ...

A function implemented by a plugin that can be registered in this hook.

Arguments

action: CreatePrefetchPostFeedRelatedObjectsHookAction

Next function registered in this hook, either a custom function or Misago's standard one.

See the action section for details.

settings: DynamicSettings

The DynamicSettings object.

permissions: UserPermissionsProxy

The UserPermissionsProxy object for current user.

posts: Iterable[Post]

Iterable of Post instances to prefetch related objects for.

categories: Iterable[Category] | None = None

Iterable of categories that were already loaded. Defaults to None if not provided.

threads: Iterable[Thread] | None = None

Iterable of threads that were already loaded. Defaults to None if not provided.

thread_updates: Iterable[ThreadUpdate] | None = None,

Iterable of ThreadUpdate instances to prefetch related objects for. Defaults to None if not provided.

attachments: Iterable[Attachment] | None = None

Iterable of attachments that were already loaded. Defaults to None if not provided.

users: Iterable["User"] | None = None

Iterable of users that were already loaded. Defaults to None if not provided.

Return value

A PrefetchPostFeedRelatedObjects object to use to fetch related objects.

Action

def create_prefetch_post_feed_related_objects_action(
    settings: DynamicSettings,
    permissions: UserPermissionsProxy,
    posts: Iterable[Post],
    *,
    categories: Iterable[Category] | None=None,
    threads: Iterable[Thread] | None=None,
    thread_updates: Iterable[ThreadUpdate] | None=None,
    attachments: Iterable[Attachment] | None=None,
    users: Iterable['User'] | None=None,
) -> 'PrefetchPostFeedRelatedObjects':
    ...

Misago function used to create a PrefetchPostFeedRelatedObjects object, which is used to prefetch related objects for items displayed on a posts feed.

Arguments

settings: DynamicSettings

The DynamicSettings object.

permissions: UserPermissionsProxy

The UserPermissionsProxy object for current user.

posts: Iterable[Post]

Iterable of Post instances to prefetch related objects for.

categories: Iterable[Category] | None = None

Iterable of categories that were already loaded. Defaults to None if not provided.

threads: Iterable[Thread] | None = None

Iterable of threads that were already loaded. Defaults to None if not provided.

thread_updates: Iterable[ThreadUpdate] | None = None,

Iterable of ThreadUpdate instances to prefetch related objects for. Defaults to None if not provided.

attachments: Iterable[Attachment] | None = None

Iterable of attachments that were already loaded. Defaults to None if not provided.

users: Iterable["User"] | None = None

Iterable of users that were already loaded. Defaults to None if not provided.

Return value

A PrefetchPostFeedRelatedObjects object to use to fetch related objects.

Example

The code below implements a custom filter function that includes a new prefetch operation:

from typing import Iterable

from misago.attachments.models import Attachment
from misago.categories.models import Category
from misago.conf.dynamicsettings import DynamicSettings
from misago.permissions.proxy import UserPermissionsProxy
from misago.plugins.hooks import FilterHook
from misago.threads.models import Post, Thread
from misago.threads.prefetch import PrefetchPostFeedRelatedObjects
from misago.threadupdates.models import ThreadUpdate
from misago.users.models import User

from .plugin.models import PluginModel


def fetch_posts_plugin_data(
    data: dict,
    settings: DynamicSettings,
    permissions: UserPermissionsProxy,
):
    data["plugin_models"] = {}
    ids_to_fetch: set[int] = set()

    for post in data["posts"].values():
        ids_to_fetch.add(post.plugin_data["plugin_object_id"])

    if ids_to_fetch:
        queryset = PluginModel.objects.filter(id__in=ids_to_fetch)
        data["plugin_models"] = {u.id: u for u in queryset}


@create_prefetch_post_feed_related_objects_hook.append_filter
def include_custom_filter(
    action: CreatePrefetchPostFeedRelatedObjectsHookAction,
    settings: DynamicSettings,
    permissions: UserPermissionsProxy,
    posts: Iterable[Post],
    *,
    categories: Iterable[Category] | None = None,
    threads: Iterable[Thread] | None = None,
    thread_updates: Iterable[ThreadUpdate] | None = None,
    attachments: Iterable[Attachment] | None = None,
    users: Iterable["User"] | None = None,
) -> PrefetchPostFeedRelatedObjects:
    prefetch = action(
        settings,
        permissions,
        posts,
        categories=categories,
        threads=threads,
        thread_updates=thread_updates,
        attachments=attachments,
        users=users,
    )

    prefetch.add_operation(fetch_posts_plugin_data)

    return prefetch