plain.api 0.12.0

API for Plain.

plain.api

Build APIs using class-based views.

This package includes lightweight view classes for building APIs using the same patterns as regular HTML views. It also provides an APIKey model and support for generating OpenAPI documents.

Because Views can convert built-in types to responses, an API view can simply return a dict or list to send a JSON response back to the client. More complex responses can use the JsonResponse class.

# app/api/views.py
from plain.api.views import APIKeyView, APIView
from plain.http import JsonResponse
from plain.views.exeptions import ResponseException

from app.users.models import User
from app.pullrequests.models import PullRequest


# An example base class that will be used across your custom API
class BaseAPIView(APIView, APIKeyView):
    def use_api_key(self):
        super().use_api_key()

        if user := self.api_key.users.first():
            self.request.user = user
        else:
            raise ResponseException(
                JsonResponse(
                    {"error": "API key not associated with a user."},
                    status_code=403,
                )
            )


# An endpoint that returns the current user
class UserView(BaseAPIView):
    def get(self):
        return {
            "uuid": self.request.user.uuid,
            "username": self.request.user.username,
            "time_zone": str(self.request.user.time_zone),
        }


# An endpoint that filters querysets based on the user
class PullRequestView(BaseAPIView):
    def get(self):
        try:
            pull = (
                PullRequest.objects.all()
                .visible_to_user(self.request.user)
                .get(uuid=self.url_kwargs["uuid"])
            )
        except PullRequest.DoesNotExist:
            return None

        return {
            "uuid": pull.uuid,
            "state": pull.state,
            "number": pull.number,
            "host_url": pull.host_url,
            "host_created_at": pull.host_created_at,
            "host_updated_at": pull.host_updated_at,
            "host_merged_at": pull.host_merged_at,
            "author": {
                "uuid": pull.author.uuid,
                "display_name": pull.author.display_name,
            },
        }

URLs work like they do everywhere else, though it's generally recommended to put everything together into an app.api package and api namespace.

# app/api/urls.py
from plain.urls import Router, path

from . import views


class APIRouter(Router):
    namespace = "api"
    urls = [
        path("user/", views.UserView),
        path("pullrequests/<uuid:uuid>/", views.PullRequestView),
    ]

Authentication and authorization

Handling authentication in the API is pretty straightforward. If you use API keys, then the APIKeyView will parse the Authorization: Bearer <token> header and set self.api_key. You will then customize the use_api_key method to associate the request with a user (or team, for example), depending on how your app works.

class BaseAPIView(APIView, APIKeyView):
    def use_api_key(self):
        super().use_api_key()

        if user := self.api_key.users.first():
            self.request.user = user
        else:
            raise ResponseException(
                JsonResponse(
                    {"error": "API key not associated with a user."},
                    status_code=403,
                )
            )

When it comes to authorizing actions, typically you will factor this in to the queryset to only return objects that the user is allowed to see. If a response method (get, post, etc.) returns None, then the view will return a 404 response. Other status codes can be returned with an int (ex. 403) or a JsonResponse object.

class PullRequestView(BaseAPIView):
    def get(self):
        try:
            pull = (
                PullRequest.objects.all()
                .visible_to_user(self.request.user)
                .get(uuid=self.url_kwargs["uuid"])
            )
        except PullRequest.DoesNotExist:
            return None

        # ...return the authorized data here

PUT, POST, and PATCH

One way to handle PUT, POST, and PATCH endpoints is to use standard forms. This will use the same validation and error handling as an HTML form, but will parse the input from the JSON request instead of HTML form data.

class UserForm(ModelForm):
    class Meta:
        model = User
        fields = [
            "username",
            "time_zone",
        ]

class UserView(BaseAPIView):
    def patch(self):
        form = UserForm(
            request=self.request,
            instance=self.request.user,
        )

        if form.is_valid():
            user = form.save()
            return {
                "uuid": user.uuid,
                "username": user.username,
                "time_zone": str(user.time_zone),
            }
        else:
            return {"errors": form.errors}

If you don't want to use Plain's forms, you could also use a third-party schema/validation library like Pydantic or Marshmallow. But depending on your use case, you may not need to use forms or fancy validation at all!

DELETE

Deletes can be handled in the delete method of the view. Most of the time this just means getting the object, deleting it, and returning a 204.

class PullRequestView(BaseAPIView):
    def delete(self):
        try:
            pull = (
                PullRequest.objects.all()
                .visible_to_user(self.request.user)
                .get(uuid=self.url_kwargs["uuid"])
            )
        except PullRequest.DoesNotExist:
            return None

        pull.delete()

        return 204

API keys

The provided APIKey model includes randomly generated, unique API tokens that are automatically parsed by APIKeyView. The tokens can optionally be named and include an expires_at date.

Associating an APIKey with a user (or team, for example) is up to you. Most likely you will want to use a ForeignKey or a ManyToManyField.

# app/users/models.py
from plain import models
from plain.api.models import APIKey


@models.register_model
class User(models.Model):
    # other fields...
    api_key = models.ForeignKey(
        APIKey,
        on_delete=models.CASCADE,
        related_name="users",
        allow_null=True,
        required=False,
    )

    class Meta:
        constraints = [
            models.UniqueConstraint(
                fields=["api_key"],
                condition=models.Q(api_key__isnull=False),
                name="unique_user_api_key",
            ),
        ]

Generating API keys is something you will need to do in your own code, wherever it makes sense to do so.

user = User.objects.first()
user.api_key = APIKey.objects.create()
user.save()

To use API keys in your views, you can inherit from APIKeyView and customize the use_api_key method to set the request.user attribute (or any other attribute) to the object associated with the API key.

# app/api/views.py
from plain.api.views import APIKeyView, APIView


class BaseAPIView(APIView, APIKeyView):
    def use_api_key(self):
        super().use_api_key()

        if user := self.api_key.users.first():
            self.request.user = user
        else:
            raise ResponseException(
                JsonResponse(
                    {"error": "API key not associated with a user."},
                    status_code=403,
                )
            )

OpenAPI

You can use a combination of decorators to help generate an OpenAPI document for your API.

To define root level schema, use the @openapi.schema decorator on your Router class.

from plain.urls import Router, path
from plain.api import openapi
from plain.assets.views import AssetView
from . import views


@openapi.schema({
    "openapi": "3.0.0",
    "info": {
        "title": "PullApprove API",
        "version": "4.0.0",
    },
    "servers": [
        {
            "url": "https://4.pullapprove.com/api/",
            "description": "PullApprove API",
        }
    ],
})
class APIRouter(Router):
    namespace = "api"
    urls = [
        # ...your API routes
    ]

You can then define additional schema on a view class, or a specific view method.

class CurrentUserAPIView(BaseAPIView):
    @openapi.schema({
        "summary": "Get current user",
    })
    def get(self):
        if self.request.user:
            user = self.request.user
        else:
            raise Http404

        return schemas.UserSchema.from_user(user, self.request)

While you can attach any raw schema you like, there are a couple helpers to generate schema for API input (@openapi.request_form) and output (@openapi.response_typed_dict). These are intentionally specific, leaving room for custom decorators to be written for the input/output types of your choice.

class TeamAccountAPIView(BaseAPIView):
    @openapi.request_form(TeamAccountForm)
    @openapi.response_typed_dict(200, TeamAccountSchema)
    def patch(self):
        form = TeamAccountForm(request=self.request, instance=self.team_account)

        if form.is_valid():
            team_account = form.save()
            return TeamAccountSchema.from_team_account(
                team_account, self.request
            )
        else:
            return {"errors": form.errors}

    @cached_property
    def team_account(self):
        try:
            if self.organization:
                return TeamAccount.objects.get(
                    team__organization=self.organization, uuid=self.url_kwargs["uuid"]
                )

            if self.request.user:
                return TeamAccount.objects.get(
                    team__organization__in=self.request.user.organizations.all(),
                    uuid=self.url_kwargs["uuid"],
                )
        except TeamAccount.DoesNotExist:
            raise Http404


class TeamAccountForm(ModelForm):
    class Meta:
        model = TeamAccount
        fields = ["is_reviewer", "is_admin"]


class TeamAccountSchema(TypedDict):
    uuid: UUID
    account: AccountSchema
    is_admin: bool
    is_reviewer: bool
    api_url: str

    @classmethod
    def from_team_account(cls, team_account, request) -> "TeamAccountSchema":
        return cls(
            uuid=team_account.uuid,
            is_admin=team_account.is_admin,
            is_reviewer=team_account.is_reviewer,
            api_url=request.build_absolute_uri(
                reverse("api:team_account", uuid=team_account.uuid)
            ),
            account=AccountSchema.from_account(team_account.account, request),
        )

To generate the OpenAPI JSON, run the following command (including swagger.io validation):

plain api generate-openapi --validate

Deploying

To build the JSON when you deploy, add a build.run command to your pyproject.toml file:

[tool.plain.build.run]
openapi = {cmd = "plain api generate-openapi --validate > app/assets/openapi.json"}

You will typically want app/assets/openapi.json to be included in your .gitignore file.

Then you can use an AssetView to serve the openapi.json file.

from plain.urls import Router, path
from plain.assets.views import AssetView
from . import views

class APIRouter(Router):
    namespace = "api"
    urls = [
        # ...your API routes
        path("openapi.json", AssetView.as_view(asset_path="openapi.json")),
    ]