1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
==========
Validators
==========
.. module:: django.core.validators
:synopsis: Validation utilities and base classes
Writing validators
==================
A validator is a callable that takes a value and raises a
:exc:`~django.core.exceptions.ValidationError` if it doesn't meet some
criteria. Validators can be useful for re-using validation logic between
different types of fields.
For example, here's a validator that only allows even numbers::
from django.core.exceptions import ValidationError
def validate_even(value):
if value % 2 != 0:
raise ValidationError(u'%s is not an even number' % value)
You can add this to a model field via the field's :attr:`~django.db.models.Field.validators`
argument::
from django.db import models
class MyModel(models.Model):
even_field = models.IntegerField(validators=[validate_even])
Because values are converted to Python before validators are run, you can even
use the same validator with forms::
from django import forms
class MyForm(forms.Form):
even_field = forms.IntegerField(validators=[validate_even])
You can also use a class with a ``__call__()`` method for more complex or
configurable validators. :class:`RegexValidator`, for example, uses this
technique. If a class-based validator is used in the
:attr:`~django.db.models.Field.validators` model field option, you should make
sure it is :ref:`serializable by the migration framework
<migration-serializing>` by adding :ref:`deconstruct()
<custom-deconstruct-method>` and ``__eq__()`` methods.
How validators are run
======================
See the :doc:`form validation </ref/forms/validation>` for more information on
how validators are run in forms, and :ref:`Validating objects
<validating-objects>` for how they're run in models. Note that validators will
not be run automatically when you save a model, but if you are using a
:class:`~django.forms.ModelForm`, it will run your validators on any fields
that are included in your form. See the
:doc:`ModelForm documentation </topics/forms/modelforms>` for information on
how model validation interacts with forms.
Built-in validators
===================
The :mod:`django.core.validators` module contains a collection of callable
validators for use with model and form fields. They're used internally but
are available for use with your own fields, too. They can be used in addition
to, or in lieu of custom ``field.clean()`` methods.
``RegexValidator``
------------------
.. class:: RegexValidator([regex=None, message=None, code=None, inverse_match=None, flags=0])
:param regex: If not ``None``, overrides :attr:`regex`. Can be a regular
expression string or a pre-compiled regular expression.
:param message: If not ``None``, overrides :attr:`.message`.
:param code: If not ``None``, overrides :attr:`code`.
:param inverse_match: If not ``None``, overrides :attr:`inverse_match`.
:param flags: If not ``None``, overrides :attr:`flags`. In that case,
:attr:`regex` must be a regular expression string, or
:exc:`TypeError` is raised.
.. attribute:: regex
The regular expression pattern to search for the provided ``value``,
or a pre-compiled regular expression. By default, raises a
:exc:`~django.core.exceptions.ValidationError` with :attr:`message`
and :attr:`code` if a match is not found. That standard behavior can
be reversed by setting :attr:`inverse_match` to ``True``, in which case
the :exc:`~django.core.exceptions.ValidationError` is raised when a
match **is** found. By default, matches any string (including an empty
string).
.. attribute:: message
The error message used by
:exc:`~django.core.exceptions.ValidationError` if validation fails.
Defaults to ``"Enter a valid value"``.
.. attribute:: code
The error code used by :exc:`~django.core.exceptions.ValidationError`
if validation fails. Defaults to ``"invalid"``.
.. attribute:: inverse_match
.. versionadded:: 1.7
The match mode for :attr:`regex`. Defaults to ``False``.
.. attribute:: flags
.. versionadded:: 1.7
The flags used when compiling the regular expression string :attr:`regex`.
If :attr:`regex` is a pre-compiled regular expression, and :attr:`flags` is overridden,
:exc:`TypeError` is raised.
Defaults to `0`.
``URLValidator``
----------------
.. class:: URLValidator([schemes=None, regex=None, message=None, code=None])
A :class:`RegexValidator` that ensures a value looks like a URL, and raises
an error code of ``'invalid'`` if it doesn't. In addition to the optional
arguments of its parent :class:`RegexValidator` class, ``URLValidator``
accepts an extra optional attribute:
.. attribute:: schemes
URL/URI scheme list to validate against. If not provided, the default
list is ``['http', 'https', 'ftp', 'ftps']``. As a reference, the IANA
Web site provides a full list of `valid URI schemes`_.
.. _valid URI schemes: https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
.. versionchanged:: 1.7
The optional ``schemes`` attribute was added.
``validate_email``
------------------
.. data:: validate_email
An ``EmailValidator`` instance that ensures a value looks like an
email address.
``validate_slug``
-----------------
.. data:: validate_slug
A :class:`RegexValidator` instance that ensures a value consists of only
letters, numbers, underscores or hyphens.
``validate_ipv4_address``
-------------------------
.. data:: validate_ipv4_address
A :class:`RegexValidator` instance that ensures a value looks like an IPv4
address.
``validate_ipv6_address``
-------------------------
.. data:: validate_ipv6_address
Uses ``django.utils.ipv6`` to check the validity of an IPv6 address.
``validate_ipv46_address``
--------------------------
.. data:: validate_ipv46_address
Uses both ``validate_ipv4_address`` and ``validate_ipv6_address`` to
ensure a value is either a valid IPv4 or IPv6 address.
``validate_comma_separated_integer_list``
-----------------------------------------
.. data:: validate_comma_separated_integer_list
A :class:`RegexValidator` instance that ensures a value is a
comma-separated list of integers.
``MaxValueValidator``
---------------------
.. class:: MaxValueValidator(max_value)
Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
``'max_value'`` if ``value`` is greater than ``max_value``.
``MinValueValidator``
---------------------
.. class:: MinValueValidator(min_value)
Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
``'min_value'`` if ``value`` is less than ``min_value``.
``MaxLengthValidator``
----------------------
.. class:: MaxLengthValidator(max_length)
Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
``'max_length'`` if the length of ``value`` is greater than ``max_length``.
``MinLengthValidator``
----------------------
.. class:: MinLengthValidator(min_length)
Raises a :exc:`~django.core.exceptions.ValidationError` with a code of
``'min_length'`` if the length of ``value`` is less than ``min_length``.
|
