title: WTF form.validate_on_submit() not working
body: <p>I have the following code and I'm submitting a form. When I hit the submit button, my form validation prints out <code>False</code>. I've checked and made sure I'm including everything from different posts, but I can't get it to validate. Is there anything I'm doing wrong?</p>
  
  <pre><code>@app.route('/index.html', methods=['GET', 'POST'])
      def index():   
              user = {'nickname': 'Rafa'}
              form = FilterForm()
              print("about to validate", file=sys.stderr)
              if form.validate_on_submit():
                      print("validated", file=sys.stderr)
                      filters_array = form.filter.split(',')
                      streaming(filters_array)
                      response = {"response", "yes"}
                      redirect("/authenticate")
  
  
  
              return render_template('index.html',
                      title="Home",
                      user=user,
                      form=form)
  
      class FilterForm(Form):
              filter = StringField('filter', validators=[DataRequired()])
  </code></pre>
  
  <p>Here is my Jinja file</p>
  
  <pre><code>    {% block content %}    
        &lt;h1&gt; I have successfully navigated to the title pagee &lt;/h1&gt; 
        &lt;h1&gt; Hello, {{user.nickname}}!&lt;/h1&gt; 
        &lt;h1&gt; Get Tweets &lt;/h1&gt; 
        &lt;p&gt; Please enter a comma delimited list of filters&lt;/p&gt;   
        &lt;form action="" method="post" name="login"&gt; 
          {{form.filter(size=80)}} 
        &lt;input type="submit" value="Get Tweets!"&gt; 
        &lt;/form&gt; 
      {% endblock %}
  </code></pre>