1FAQ
2===
3
4This contains the most commonly asked questions about WTForms. The most current
5version of this document can always be found on the `WTForms Website`_.
6
7.. _WTForms Website: http://wtforms.simplecodes.com
8
9
10Does WTForms work with [library here]?
11--------------------------------------
12
13The answer is most likely **yes**. WTForms tries to provide as usable an API as
14possible. We've listed here some of the known libraries to work with WTForms,
15but if it's not listed, it doesn't mean it won't work.
16
17* **Request/Form Input**
18
19  * Django
20  * Webob (Includes Pylons, Google App Engine, Turbogears)
21  * Werkzeug (Includes Flask, Tipfy)
22  * any other cgi.FieldStorage-type multidict
23
24* **Templating Engines**
25
26  * Jinja2
27  * Mako
28  * Django Templates (To get the full power of WTForms in your templates, you
29    will need to use the Django :mod:`extension <wtforms.ext.django>`.)
30  * Genshi
31
32* **Database Objects**
33
34  * Pretty much any ORM or object-DB should work, as long as data objects allow
35    attribute access to their members.
36
37    Special support is there for SQLAlchemy, Google App Engine, and Django
38    collections via :mod:`extensions <wtforms.ext>`.
39
40
41Does WTForms support unicode?
42-----------------------------
43
44Simple answer: Yes.
45
46Longer answer: WTForms uses unicode strings throughout the source code, and
47assumes that form input has already been coerced to unicode by your framework
48(Most frameworks already do this.) WTForms fields render to unicode strings by
49default, and therefore as long as your templating engine can work with that,
50you should have no unicode issues.
51
52
53What versions of Python are supported?
54--------------------------------------
55
56WTForms supports Python 2.6-2.7 and 3.2+ with a single codebase. Without 2to3 tool.
57
58
59How can I contribute to WTForms?
60--------------------------------
61
62WTForms is not that scary. Really. We try to keep it as succint and readable as
63possible. If you feel like you have something to contribute to WTForms, let us
64know on the `mailing list`_. For bugs and feature requests, you can file a
65ticket on the `project page`_.
66
67.. _mailing list: http://groups.google.com/group/wtforms
68.. _project page: http://github.com/wtforms/wtforms
69
70
71How do I mark in a template when a field is required?
72-----------------------------------------------------
73
74Some validators (notably Required and Optional) set flags on the fields'
75:attr:`~wtforms.fields.Field.flags` object. To use this in a template, you can
76do something like:
77
78.. code-block:: html+jinja
79
80    {% for field in form %}
81        {{ field }}
82        {% if field.flags.required %}*{% endif %}{{ field.label }}
83    {% endfor %}
84
85
86Does WTForms handle file uploads?
87---------------------------------
88
89Currently, it does not. This is because WTForms strives to be
90framework-agnostic, and every web framework handles file uploads somewhat
91differently. WTForms has a :class:`~wtforms.fields.FileField` which will let
92you render a file input widget, but the rest is up to you. An example use in a
93django-ish framework::
94
95    class MyForm(Form):
96        image = FileField()
97
98    def my_view(request):
99        form = MyForm(request.POST)
100        file_wrapper = request.FILES[form.image.name]
101        # Do things with your file wrapper now
102
103Using ``form.image.name`` is an easy way to know what input name was generated
104for your file input, even if the form is prefixed.
105
106
107Why does blank input not go back to the default value?
108------------------------------------------------------
109
110A key design decision of WTForms was that form data -always- takes precedence
111when there's a form submission. That is, if a field exists on a form, and a
112form was posted, but that field's value was missing, it will not revert to a
113default, but instead store an empty value (and in some cases cause a validation
114error.)
115
116This is for a number of reasons:
117
1181. Security. If a form reverted to defaults on missing data, then an evil user
119   could potentially cause problems by submitting a hand-coded form with key
120   missing fields.
121
1222. Bug-finding. If you omitted a field in your template, it might fall through
123   to the default and you'd possibly miss it.
124
1253. Consistency.
126
127See the following mailing list posts for more discussion on the topic:
128 - http://groups.google.com/group/wtforms/browse_frm/thread/6755a45a13878e9
129 - http://groups.google.com/group/wtforms/msg/fa409c8c89b6f62d
130
131
132How do I... [convoluted combination of libraries]
133-------------------------------------------------
134
135You'll probably want to check out our
136:ref:`Solving Specific Problems <specific_problems>` doc.
137