AttributeError: 'EditForm' object has no attribute 'validate_on_submit'

Question

I have a small edit app with the files bellow. When I submit tbe form it shows me AttributeError: 'EditForm' object has no attribute 'validate_on_submit' Can anyone please tell me what is the issue?

forms.py

from flask.ext.wtf import Form
from wtforms import Form, TextField, BooleanField, PasswordField, TextAreaField, validators
from wtforms.validators import Required

class EditForm(Form):
    """edit user Profile EditForm"""
    username = TextField('username', [validators.Length(min=3, max=50), validators.Required()])
    email = TextField('email', [validators.Length(min=5, max=100), validators.Email, validators.Required()])
    password = PasswordField('password', [validators.Required()])
    age = TextField('age', [validators.Length(min=1, max=3), validators.Required()])
    about_user = TextAreaField('about_user', [validators.Length(max=500)])
    img_url = TextField('img_url')

views.py

from flask import render_template, url_for, flash, g, redirect, session, request
from flask.ext.login import login_user, logout_user, current_user, login_required
from forms import LoginForm, RegisterForm, EditForm

@app.route('/edit', methods = ['GET', 'POST'])
def edit():
    form = EditForm(request.form)

    if request.method == 'POST' and form.validate_on_submit():
        g.user.username = form.data.username
        g.user.email = form.data.email
        g.user.age = form.data.age
        g.user.img_url = form.data.img_url
        g.user.about_user = form.data.about_user
        db.session.add(g.user)
        db.session.commit()
        flash('Your changes saved successfully')
        return redirect(url_for('edit')) 
    else:
        form.data.username = g.user.username
        form.data.email = g.user.email
        form.data.age = g.user.age
        form.data.img_url = g.user.img_url
        form.data.about_user = g.user.about_user
    return render_template('edit.html',
        title = 'Edit Profile',
        form = form)

edit.html

{% extends "base.html" %}
{% block content %}
    <div>
    <form action="" method="post" name="edit">
        <table>
            <tr>
                <td>Username</td>
                <td>{{ form.username }}</td>
            </tr>
            <tr>
                <td>E-mail</td>
                <td>{{ form.email }}</td>
            </tr> 
            <tr>
                <td>Age</td>
                <td>{{ form.age }}</td>
            </tr>
            <tr>
                <td>Choose Avatar</td>
                <td>{{ form.img_url }}</td>
            </tr>
            <tr>
                <td>About me</td>
                <td>{{ form.about_user(cols = 50, rows = 5) }}</td>
            </tr>
            <tr>
                <td></td>
                <td><input type="submit" name="submit" value="Save changes"/></td>              </tr>
            </table>
        </form>
    </div>
{% endblock %}

Answer 1

You imported the wrong Form object:

from flask.ext.wtf import Form
from wtforms import Form, TextField, BooleanField, PasswordField, TextAreaField, validators

The second import line imports Form from wtforms, replacing the import from flask_wtf. Remove Form from the second import line (and update your flask.ext.wtf import to flask_wtf to remain future-proof):

from flask_wtf import Form
from wtforms import TextField, BooleanField, PasswordField, TextAreaField, validators

Two additional notes:

1. The form will take values from the request for you, no need to pass in request.form.

2. validate_on_submit() tests for the request method too, no need to do so yourself.

The following then is enough:

@app.route('/edit', methods = ['GET', 'POST'])
def edit():
    form = EditForm()

    if form.validate_on_submit():

And as of Flask-WTF version 0.13 (released 2016/09/29), the correct object to use is named FlaskForm, to make it easier to distinguish between it and the wtforms Form class:

from flask_wtf import FlaskForm