Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python

Posted by Rastko Jovic
Rastko Jovic
14,883 Points

FLASK: Form Validation not working!

I am trying to return a success message upon form validation but it doesn't work! Here is the code:

app.py

@app.route('/', methods=['GET','POST'])
def index():
    signin_form = forms.SignInForm()
    if signin_form.validate_on_submit():
        return 'Form validated!'
    # If form not validated properly do this...
    return render_template('index.html', signin_form=signin_form)

forms.py

class SignInForm(FlaskForm):

    username = StringField('Username', validators=[DataRequired()])
    password = PasswordField('Password', validators=[DataRequired()])

macro.html

{% macro render_field(field) %}
    {{ field.label }}
    <input type="text" name="{{ field.label.text.lower() }}" id = "{{ field.label.text.lower() }}">
    {% if field.errors %}
        {% for error in field.errors %}
            <p class="error">{{ error }}</p>
        {% endfor %}
    {% endif %}
{% endmacro %}

index.html

<body>
    <!-- Log In Form-->
    <form action="" method="POST" name="signin_form">
        <h3>Sign In</h3>
        {{ render_field(signin_form.username) }}<br>
        {{ render_field(signin_form.password) }}
        <input type="submit" value="Sign In">
    </form>

    </form>
</body>

2 Answers

Andreas cormack
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points
Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

I have always used the Form class rather than FlaskForm. Not sure, may be someone else would know the difference between the two.

below is an example of one of my forms.

from flask_wtf import Form
from wtforms import StringField, PasswordField,TextAreaField
from wtforms.validators import (DataRequired, Regexp, ValidationError, Email,
                               Length, EqualTo)


class LoginForm(Form):
    email = StringField('Email', validators=[DataRequired(), Email()])
    password = PasswordField('Password', validators=[DataRequired()])
Andreas cormack
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points
Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

Hi Rastko

class SignInForm(Form): # i think here it should be Form rather than FlaskForm

    username = StringField('Username', validators=[DataRequired()])
    password = PasswordField('Password', validators=[DataRequired()])
Rastko Jovic
Rastko Jovic
14,883 Points

In the flask_wtf documentation an example is shown:

from flask_wtf import FlaskForm
from wtforms import StringField
from wtforms.validators import DataRequired

class MyForm(FlaskForm):
    name = StringField('name', validators=[DataRequired()])

https://flask-wtf.readthedocs.io/en/stable/quickstart.html#creating-forms