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

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