Rest in Peace (RIP)

RIP is a python-based framework for writing a http-api. It is generic enough to create non RESTful apis too. Its currently written to support Django but can be easily extended for any other web-frameworks (like Flask, for instance).

Getting started

Create a new (RIP) API object, like so

from rip.api import Api
my_api = Api(name='api', version='0.1')

To the newly created api, you can add resources (endpoints). Resources are where users will make http requests. Let's see how to define a resource (we will define an example "Tweet" resource)

from rip.crud.crud_resource import CrudResource, CrudActions
class Tweet(CrudResource):
    schema_cls = TweetSchema
    allowed_actions= [CrudActions.READ_LIST,
                        CrudActions.READ_DETAIL,
                        CrudActions.UPDATE_DETAIL,
                        CrudActions.CREATE_DETAIL,
                        CrudActions.DELETE_DETAIL]
    entity_actions_cls = TweetEntityActions
    serializer_cls = TweetEntitySerializer
    authorization_cls = TweetAuthorization
    allowed_filters = {'id': (EQUALS)}
    default_limit = 20
    default_offset = 0

Above, we defined a CRUD type resource called 'Tweet'. By defining it as a CRUD (or RESTful) resource, we need to give it some more configuration. As a typical REST resource, it needs a schema (a list of fields on that resource), and a set of actions that can be performed on that resource (allowed_actions). Its easy to see how you can restrict the actions that can be performed on the resource.

Lets see how the schema itself is defined.

from rip.api_schema import ApiSchema
from rip.filter_types import EQUALS
from rip.schema.base_field import FieldTypes
from rip.schema import fields

class TweetSchema(ApiSchema):
    id = fields.StringField(max_length=10, required=True,
                     field_type=FieldTypes.READONLY)
    author = fields.StringField(max_length=100, required=True,
                       field_type=FieldTypes.READONLY)
    body = fields.StringField(max_length=100, required=True,
                               field_type=FieldTypes.READONLY)
    is_active = fields.BooleanField(required=True)
    resource_uri = fields.ResourceUriField()

    class Meta:
        schema_name = 'tweet'

Now, lets examine the Tweet resource again. What are entity_actions and schema_mapper?

This is the slightly complex part. RIP assumes that each resource is constructed from an entity. To be specific, every field of the resource can be constructed from one or more fields on the corresponding entity. Entities, typically, are business objects that mean something speciic to your app. In this case, it is likely that your app has an internal entity called tweet which will be used. In simple Django projects, entities can also be django.model.Model objects.

The entity_actions configuration defines a how these entities are generated. Here's an example definition.

from myapp.models import Tweet
from rip.generic_steps.default_entity_actions import DefaultEntityActions

class TweetEntityActions(DefaultEntityActions):
    def get_entity_list(self, request, **kwargs):
        return Tweet.objects.filter(**kwargs)

    def update_entity(self, request, entity, **update_params):
        return Tweet.objects.update(id=entity.id, **update_params)

    def get_entity_list_total_count(self, request, **kwargs):
        return Tweet.objects.count(**kwargs)

Next, the entity_serializer is a class with functions (like serialize_fieldname) that describe how the fieldname in the resource is created from entities. If left blank, we simply pull the same fieldname from the entity.

from rip.generic_steps.default_entity_serializer import DefaultEntitySerializer

class TweetEntitySerializer(DefaultEntitySerializer):
    def serialize_author(self, request, entity):
        return entity.full_name

Next, lets look at the authorization property of the Tweet resource. It defines any specific rules that you might want to implement to allow/deny access to certain actions or resource endpoints.

from rip import error_types
from rip.generic_steps.default_authorization import DefaultAuthorization
from rip.response import Response

class TweetAuthorization(DefaultAuthorization):
    def authorize_read_detail(self, request):
        if request.user.username != request.entity.author.username:
            return Response(is_success=False, reason=error_types.ObjectNotFound)
        return request

And, that's it :)

Under the Hood

Underneath, RIP is simply designed as a collection of actions. A resource is just a container of a few actions (typically bound together as per some business needs). Each action is implemented as a pipeline of functions. Each of these functions take a request/response, potentially modify it, and pass on the result to the next function in the pipeline. To those who are familiar with Django Middleware, this follows a similar pattern.

One last thing

Another cool feature of RIP is that it also exposes a python API (along with the HTTP api). This allows you to use the api internally without requiring to make HTTP calls. For instance,

• when one API call internally requires making another API call
• an internal function or backend job is best represented by an API call
• testing your API (without selenium)

You can call actions on your api objects easily, like so

tweet_resource = Tweet()
response = tweet_resource.read_list(request)