.. _ref-validation: ========== Validation ========== Validation allows you to ensure that the data being submitted by the user is appropriate for storage. This can range from simple type checking on up to complex validation that compares different fields together. If the data is valid, an empty dictionary is returned and processing continues as normal. If the data is invalid, a dictionary of error messages (keys being the field names, values being a list of error messages). This will be immediately returned to the user, serialized in the format they requested. Usage ===== Using these classes is simple. Simply provide them (or your own class) as a ``Meta`` option to the ``Resource`` in question. For example:: from django.contrib.auth.models import User from tastypie.validation import Validation from tastypie.resources import ModelResource class UserResource(ModelResource): class Meta: queryset = User.objects.all() resource_name = 'auth/user' excludes = ['email', 'password', 'is_superuser'] # Add it here. validation = Validation() Validation Options ================== Tastypie ships with the following ``Validation`` classes: ``Validation`` ~~~~~~~~~~~~~~ The no-op validation option, the data submitted is always considered to be valid. This is the default class hooked up to ``Resource/ModelResource``. ``FormValidation`` ~~~~~~~~~~~~~~~~~~ A more complex form of validation, this class accepts a ``form_class`` argument to its constructor. You supply a Django ``Form`` (or ``ModelForm``, though ``save`` will never get called) and Tastypie will verify the ``data`` in the ``Bundle`` against the form. .. warning:: Data in the bundle must line up with the fieldnames in the ``Form``. If they do not, you'll need to either munge the data or change your form. Usage looks like:: from django import forms class NoteForm(forms.Form): title = forms.CharField(max_length=100) slug = forms.CharField(max_length=50) content = forms.CharField(required=False, widget=forms.Textarea) is_active = forms.BooleanField() form = FormValidation(form_class=NoteForm) Implementing Your Own Validation ================================ Implementing your own ``Validation`` classes is a simple process. The constructor can take whatever ``**kwargs`` it needs (if any). The only other method to implement is the ``is_valid`` method:: from tastypie.validation import Validation class AwesomeValidation(Validation): def is_valid(self, bundle, request=None): if not bundle.data: return {'__all__': 'Not quite what I had in mind.'} errors = {} for key, value in bundle.data.items(): if not isinstance(value, basestring): continue if not 'awesome' in value: errors[key] = ['NOT ENOUGH AWESOME. NEEDS MORE.'] return errors Under this validation, every field that's a string is checked for the word 'awesome'. If it's not in the string, it's an error.