wtforms, CSRF, flask, FieldList

Question

I'm having trouble passing through validation when using a FieldList with WTForms. I keep getting this error. {'csrf_token': [u'CSRF token missing']}. The problem is if I do not have any data to validate in the FieldList field, the validation passes and there are no issues. But when I try to validate the form with any data I get that error.

Here are my forms:

class FilterForm(wtf.Form):
    filter_value = wtf.TextField('Value', validators=[validators.Required()])
    filter_operator = wtf.SelectField('Operator', validators=[validators.Required()])
    filter_compare_value=wtf.TextField('Compare Value', validators=[validators.Required()])


class RedirectForm(wtf.Form):
    redirect_id = wtf.HiddenField('id')
    redirect_name = wtf.TextField('Name', validators=[validators.Required()])
    redirect_url = wtf.TextField('URL', validators=[validators.Required()])
    redirect_type = wtf.SelectField('Type', validators=[validators.Required()])
    redirect_method = wtf.SelectField('Method', validators=[validators.Required()])
    redirect_active = wtf.BooleanField('Is Active')
    redirect_filters_any = wtf.FieldList(wtf.FormField(FilterForm))
    redirect_filters_all = wtf.FieldList(wtf.FormField(FilterForm))

The form seems to display correctly and works fine until I add data to either redirect_filters_any or redirect_filters_all

Is there a way to disable csrf for the FieldList or pass a CSRF value to the FieldList? I want to keep CSRF protection enabled but can not seem to get past this validation problem.

Here is the Jinja2 template

{% extends "base.html" %}
{% set active_page = "endpoints" %}
{% block tail_script %}
<script src="/static/js/page/redirects.js"></script>
{% endblock %}
{% block content %}
<div class="row12">
    <div class="span12">
        <ul class="breadcrumb">
              <li><a href="{{ url_for('list_endpoints') }}">Endpoints</a> <span class="divider">/</span></li>
              <li><a href="{{ url_for('show_endpoint', id=endpoint_id) }}">{{endpoint_name}}</a> <span class="divider">/</span></li>
              {% if redirect_id != 'new' %}
              <li class="active">{{ form.redirect_name.data }}</li>
              {% else %}
              <li class="active">New</li>
              {% endif %}
        </ul>
        <form action="{{ url_for('edit_redirect', endpoint_id=endpoint_id, redirect_id=redirect_id) }}" class="form-horizontal" method="post">
            <legend>General</legend>
            {{ form.hidden_tag() }}
            <div class="control-group {% if form.redirect_name.errors %}error{% endif %}">
                <div class="control-label">{{ form.redirect_name.label }}</div>
                <div class="controls">
                    {{ form.redirect_name|safe }}
                    {% if form.redirect_name.errors %}
                    <span class="help-inline">
                         <ul class="errors">
                            {% for error in form.redirect_name.errors %}
                            <li>{{ error }}</li>
                            {% endfor %}
                        </ul>
                    </span>
                   {% endif %}
                </div>
            </div>
            <div class="control-group {% if form.redirect_type.errors %}error{% endif %}">
                <div class="control-label">{{ form.redirect_type.label }}</div>
                <div class="controls">
                    {{ form.redirect_type|safe }}
                    {% if form.redirect_type.errors %}
                    <span class="help-inline">
                         <ul class="errors">
                            {% for error in form.redirect_type.errors %}
                            <li>{{ error }}</li>
                            {% endfor %}
                        </ul>
                    </span>
                   {% endif %}
                </div>
            </div>
            <div class="control-group {% if form.redirect_active.errors %}error{% endif %}">
                <div class="control-label">{{ form.redirect_active.label }}</div>
                <div class="controls">
                    {{ form.redirect_active|safe }}
                    {% if form.redirect_active.errors %}
                    <span class="help-inline">
                         <ul class="errors">
                            {% for error in form.redirect_active.errors %}
                            <li>{{ error }}</li>
                            {% endfor %}
                        </ul>
                    </span>
                   {% endif %}
                </div>
            </div>
            <div class="control-group {% if form.redirect_method.errors %}error{% endif %}">
                <div class="control-label">{{ form.redirect_method.label }}</div>
                <div class="controls">
                    {{ form.redirect_method|safe }}
                    {% if form.redirect_method.errors %}
                    <span class="help-inline">
                         <ul class="errors">
                            {% for error in form.redirect_method.errors %}
                            <li>{{ error }}</li>
                            {% endfor %}
                        </ul>
                    </span>
                   {% endif %}
                </div>
            </div>
            <div class="control-group {% if form.redirect_url.errors %}error{% endif %}">
                <div class="control-label">{{ form.redirect_url.label }}</div>
                <div class="controls">
                    {{ form.redirect_url|safe }}
                    {% if form.redirect_url.errors %}
                    <span class="help-inline">
                         <ul class="errors">
                            {% for error in form.redirect_url.errors %}
                            <li>{{ error }}</li>
                            {% endfor %}
                        </ul>
                    </span>
                   {% endif %}
                </div>
            </div>
            <legend>Meet All Filters <a href="#" class="btn addAllFilter">Add</a></legend>
            <table class="stable-striped" id="all_filter_table">
                <tbody>
            {% for f in form.redirect_filters_all %}
                <tr style="vertical-align:top;">
                    <td>    
                        {{ f.filter_value }}
                        {% if f.filter_value.errors %}
                        <br>
                        <div class="control-group error">
                            <span class="help-inline">
                                 <ul class="errors">
                                    {% for error in f.filter_value.errors %}
                                    <li>{{ error }}</li>
                                    {% endfor %}
                                </ul>
                            </span>
                        </div>
                        {% endif %}
                    </td>
                    <td>    
                        {{ f.filter_operator }}
                        {% if f.filter_operator.errors %}
                        <br>
                        <div class="control-group error">
                            <span class="help-inline">
                                 <ul class="errors">
                                    {% for error in f.filter_operator.errors %}
                                    <li>{{ error }}</li>
                                    {% endfor %}
                                </ul>
                            </span>
                        </div>
                        {% endif %}
                    </td>
                    <td>    
                        {{ f.filter_compare_value }}
                        {% if f.filter_compare_value.errors %}
                        <br>
                        <div class="control-group error">
                            <span class="help-inline">
                                 <ul class="errors">
                                    {% for error in f.filter_compare_value.errors %}
                                    <li>{{ error }}</li>
                                    {% endfor %}
                                </ul>
                            </span>
                        </div>
                        {% endif %}
                    </td>
                    <td><a href="#" class="btn remove">Remove</a></td>
                </tr>
            {% endfor %}
                </tbody>
            </table>
            <legend>Meet Any Filters <a href="#" class="btn addAnyFilter">Add</a></legend>
            <table class="stable-striped" id="any_filter_table">
                <tbody>
            {% for f in form.redirect_filters_any %}
                <tr style="vertical-align:top;">
                    <td>    
                        {{ f.filter_value }}
                        {% if f.filter_value.errors %}
                        <br>
                        <div class="control-group error">
                            <span class="help-inline">
                                 <ul class="errors">
                                    {% for error in f.filter_value.errors %}
                                    <li>{{ error }}</li>
                                    {% endfor %}
                                </ul>
                            </span>
                        </div>
                        {% endif %}
                    </td>
                    <td>    
                        {{ f.filter_operator }}
                        {% if f.filter_operator.errors %}
                        <br>
                        <div class="control-group error">
                            <span class="help-inline">
                                 <ul class="errors">
                                    {% for error in f.filter_operator.errors %}
                                    <li>{{ error }}</li>
                                    {% endfor %}
                                </ul>
                            </span>
                        </div>
                        {% endif %}
                    </td>
                    <td>    
                        {{ f.filter_compare_value }}
                        {% if f.filter_compare_value.errors %}
                        <br>
                        <div class="control-group error">
                            <span class="help-inline">
                                 <ul class="errors">
                                    {% for error in f.filter_compare_value.errors %}
                                    <li>{{ error }}</li>
                                    {% endfor %}
                                </ul>
                            </span>
                        </div>
                        {% endif %}
                    </td>
                    <td><a href="#" class="btn remove">Remove</a></td>
                </tr>
            {% endfor %}
                </tbody>
            </table>
            {% if g.user.user_type == 'admin' %}
            <div class="control-group">
                <div class="controls">
                    <input class="btn btn-primary" type="submit" value="Save"/>
                    <a href="{{url_for('show_endpoint', id=endpoint_id)}}" class="btn">Cancel</a>
                </div>
            </div>
            {% endif %}
        </form>
    </div>
</div>
{% endblock %}

Answer 1

The issue seems to be that Flask-WTForms Form is actually a subclass of wtforms.ext.SecureForm - and the only way to disable the csrf protection on a form is to pass the keyword argument csrf_enabled=False to the form when constructing it. Since FormField actually handles instantiating the form and you can either:

• Create a subclass of FormField that will let you pass in form keyword arguments
  or
• Subclass wtforms.Form rather than flask.ext.wtforms.Form for your FilterForm (as long as you never display a FilterForm on its own you won't need to worry about CSRF).

Answer 2

After encountering the same problem, I wanted to to supply a third option to the solution above

You can also override the constructor in your form class to replace the default value of csrf_enabled. This has the advantage that you can use the the same form definition as both a fieldlist member, and a standalone form with CSRF enabled by passing csrf_enabled=True.

class FilterForm(wtf.Form):
    field = wtf.Form ...

    def __init__(self, csrf_enabled=False, *args, **kwargs):
        super(FilterForm, self).__init__(csrf_enabled=csrf_enabled, *args, **kwargs)

Answer 3

It seems csrf_enabled is deprecated. Here's a solution that works with Flask-WTForms 0.14.2, partially based on leebriggs's answer. Rather than pass a parameter when creating the form, I just created a xNoCsrf subclass, because I didn't want someone to accidentally forget to include the CSRF token when they do want it. This way, you have to type NoCsrf to get the non-CSRF version.

class FilterForm(FlaskForm):
    <some stuff here>

class FilterFormNoCsrf(FilterForm):
    def __init__(self, *args, **kwargs):
        super(FilterFormNoCsrf, self).__init__(meta={'csrf':False}, *args, **kwargs)

Here is the documentation for csrf field of the meta class.

Answer 4

Since version 1.0 the new way to achieve this is as follows: This will disable the CSRF token for all instances of your Form, so be careful to only use it as a subform.

class MyForm(FlaskForm):
    class Meta:
        csrf = False

    myfield = StringField("A Field")