bumblebee211196/django_api_forms

Declarative Django request validation for APIs

Django API Forms

Django Forms approach in paring and validation of request payload (especially for content type like JSON or MessagePack) without HTML front-end.

Motivation

Main idea was to create a simple and declarative way to specify format of expecting request with ability to validate them. Firstly I tried to use Django Forms to validate my API request (I use pure Django in my APIs). I have encountered a problem with nesting my requests without huge boilerplate. Also, the whole HTML thing was pretty useless in my RESTful APIs.

I wanted something to:

• define my requests as object (Form)
• pass the request to my defined object (form = Form.create_from_request(request))
• validate my request form.is_valid()
• extract data form.clean_data property

I wanted to keep:

• friendly declarative Django syntax (DeclarativeFieldsMetaclass is beautiful)
• Validators
• ValidationError
• Form fields (In the end, I had to "replace" some of them)

So I decided to create simple Python package to cover all my expectations.

Installation

# Using pip
pip install django-api-forms

# Using poetry
peotry add django-api-forms

# Using setup.py
python setup.py install

Optional:

# msgpack support (for requests with Content-Type: application/x-msgpack)
peotry add msgpack

# ImageField support
peotry add Pillow

Install application in your Django project by adding django_api_forms to yours INSTALLED_APPS:

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django_api_forms'
)

Example

Simple nested JSON request

{
  "title": "Unknown Pleasures",
  "type": "vinyl",
  "artist": {
    "name": "Joy Division",
    "genres": [
      "rock",
      "punk"
    ],
    "members": 4
  },
  "year": 1979,
  "songs": [
    {
      "title": "Disorder",
      "duration": "3:29"
    },
    {
      "title": "Day of the Lords",
      "duration": "4:48",
      "metadata": {
        "_section": {
          "type": "ID3v2",
          "offset": 0,
          "byteLength": 2048
        },
        "header": {
          "majorVersion": 3,
          "minorRevision": 0,
          "size": 2038
        }
      }
    }
  ],
  "metadata": {
    "created_at": "2019-10-21T18:57:03+0100",
    "updated_at": "2019-10-21T18:57:03+0100"
  }
}

Django API Forms equivalent + validation

from enum import Enum

from django.core.exceptions import ValidationError
from django.forms import fields

from django_api_forms import FieldList, FormField, FormFieldList, DictionaryField, EnumField, AnyField, Form


class AlbumType(Enum):
    CD = 'cd'
    VINYL = 'vinyl'


class ArtistForm(Form):
    name = fields.CharField(required=True, max_length=100)
    genres = FieldList(field=fields.CharField(max_length=30))
    members = fields.IntegerField()


class SongForm(Form):
    title = fields.CharField(required=True, max_length=100)
    duration = fields.DurationField(required=False)
    metadata = AnyField(required=False)


class AlbumForm(Form):
    title = fields.CharField(max_length=100)
    year = fields.IntegerField()
    artist = FormField(form=ArtistForm)
    songs = FormFieldList(form=SongForm)
    type = EnumField(enum=AlbumType, required=True)
    metadata = DictionaryField(fields.DateTimeField())

    def clean_year(self):
        if self.cleaned_data['year'] == 1992:
            raise ValidationError("Year 1992 is forbidden!", 'forbidden-value')
        return self.cleaned_data['year']

    def clean(self):
        if (self.cleaned_data['year'] == 1998) and (self.cleaned_data['artist']['name'] == "Nirvana"):
            raise ValidationError("Sounds like a bullshit", code='time-traveling')
        if not self._request.user.is_authenticated():
            raise ValidationError("You can use request in form validation!")
        return self.cleaned_data



"""
Django view example
"""
def create_album(request):
    form = AlbumForm.create_from_request(request)
    if not form.is_valid():
        # Process your validation error
        print(form.errors)

    # Cleaned valid payload
    payload = form.cleaned_data
    print(payload)

If you want example with whole Django project, check out repository created by pawl django_api_forms_modelchoicefield_example, where he uses library with ModelChoiceField.

Running Tests

# install all dependencies
poetry install

# run the tests
poetry run pytest

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Made with ❤️ and ☕️ by Jakub Dubec, BACKBONE s.r.o. & contributors.