# Plugin Hooks

The following plugin hooks can be used by plugins.

## installed_apps()

Return a list of Django app strings to be added to `INSTALLED_APPS`.

Example implementation:

```python
import djp

@djp.hookimpl
def installed_apps():
    return ["my_plugin_app"]
```

## middleware()

Return a list of Django middleware class strings to be added to MIDDLEWARE.

Middleware can optionally be wrapped with `djp.Before()` or `djp.After()` to specify ordering relative to existing middleware. These will then be added to the beginning or end of the middleware list, respectively.

Example implementation:

```python
import djp

@djp.hookimpl
def middleware():
    return [
        djp.Before("django.middleware.common.CommonMiddleware"),
        "my_plugin.middleware.MyPluginMiddleware",
        djp.After("django.middleware.clickjacking.XFrameOptionsMiddleware")
    ]
```

Sometimes you may want a middleware to be inserted at an exact position relative to another middleware. You can specify that with `djp.Position()`:

```python
@djp.hookimpl
def middleware():
    return [
        # This will insert the middleware directly before CommonMiddleware
        djp.Position(
            "my_plugin.middleware.MyPluginMiddleware",
            before="django.middleware.common.CommonMiddleware"
        ),
        # And this will be inserted directly after CommonMiddleware
        djp.Position(
            "my_plugin.middleware.MyPluginMiddleware2",
            after="django.middleware.common.CommonMiddleware"
        ),
    ]
```

## urlpatterns()

Return a list of URL patterns to be added to `urlpatterns`.

Example implementation:

```python
import djp
from django.urls import path
from . import views

@djp.hookimpl
def urlpatterns():
    return [
        path("my-plugin/", views.my_plugin_view),
    ]
```

## settings(current_settings)

Modify the current Django settings in-place to configure additional settings.

`current_settings` is a dictionary representing the current settings in `settings.py`.

Example implementation:

```python
import djp

@djp.hookimpl
def settings(current_settings):
    current_settings["DATABASES"] = {
        "default": {
            "ENGINE": "django.db.backends.sqlite3",
            "NAME": "mydatabase",
        }
    }
```

(plugin_hook_asgi_wrapper)=
## asgi_wrapper()

Return a function that can wrap the Django ASGI application with new ASGI middleware.

Example implementation:

```python
import djp

@djp.hookimpl
def asgi_wrapper():
    return wrap

def wrap(app):
    async def wrapper(scope, receive, send):
        if scope["type"] == "http" and scope["path"] == "/hello":
            await send({
                "type": "http.response.start",
                "status": 200,
                "headers": [
                    [b"content-type", b"text/plain"],
                ],
            })
            await send({
                "type": "http.response.body",
                "body": b"Hello world",
            })
        else:
            await app(scope, receive, send)

    return wrapper
```