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Cross-field validators within a Django model

Project Description
================
django-xvalidate
================

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django-xvalidate allows you to declare cross-field validators within a
Django model.

As an example, consider a Django model named :code:`Event`.

.. code:: python

from django.db import models

class Event(models.Model):
title = models.CharField(max_length=255)
start_date = models.DateField()
end_date = models.DateField()

django-xvalidate allows you to declare that the start date precedes the end
date as follows:

.. code:: python

from django.db import models
from xvalidate import XValidatedModel, XLe

class Event(XValidatedModel, models.Model):
title = models.CharField(max_length=255)
start_date = models.DateField()
end_date = models.DateField()

class XVMeta(XValidatedModel.XVMeta):
spec = [
XLe('start_date', 'end_date').message(
'The start date should precede the end date')
]

:code:`XValidatedModel` ensures that this specification is maintained
invoking :code:`Event.clean()` and raises :code:`ValidationError` as
appropriate.

Why use django-xvalidate?
-------------------------
django-xvalidate allows you to specify how to validate your model instances
in a more declarative manner than writing imperative code within your
:code:`clean()` methods. Without django-xvalidate you would have to
implement the above example as

.. code:: python

def clean(self):
super(Event, self).clean()
if (self.start_date is not None) and (self.end_date is not None):
if (self.end_date < self.start_date):
raise ValidationError('The start date should precede the end date')

With a more declarative format we have the option at some point in the
future to automate the creation of test data that passes (or fails)
validation.

django-xvalidate comes some operator overloading that brings syntactic
sugar to your declarations making them very easy to read. For instance,
you could specify:

.. code:: python

((XF('end_date') - 'start_date') > datetime.timedelta(days=4)).message(
'Event should last at least 5 days'
)

django-xvalidate also allows the use of Django's double-underscore (`__`)
syntax to dereference related objects, enabling succinct definitions such
as the following

.. code:: python

(XF('registration_date') <= 'event__end_date').message(
'Must register before the event ends')
Release History

Release History

This version
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0.4.2

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0.4.1

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0.4.0

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0.3.1

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0.3.0

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0.2.0

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0.1.0

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File Name & Checksum SHA256 Checksum Help Version File Type Upload Date
django-xvalidate-0.4.2.tar.gz (5.5 kB) Copy SHA256 Checksum SHA256 Source Mar 13, 2017

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