Can anyone pls help me how to resolve this issue?

classes.py

from flask_wtf import Form
from wtforms import TextField, IntegerField, SubmitField

class CreateTask(Form):
    title = TextField('Task Title')
    shortdesc = TextField('Short Description')
    priority = IntegerField('Priority')
    create = SubmitField('Create')

class DeleteTask(Form):
    key = TextField('Task Key')
    title = TextField('Task Title')
    delete = SubmitField('Delete')

class UpdateTask(Form):
    key = TextField('Task Key')
    title = TextField('Task Title')
    shortdesc = TextField('Short Description')
    priority = IntegerField('Priority')
    update = SubmitField('Update')

class ResetTask(Form):
    reset = SubmitField('Reset')

It says - The debugger caught an exception in your WSGI application. You can now look at the traceback which led to the error.

Solution

The error is coming from your run.py file, but the main issue is from classes.py.

In the first line of your main() function:

def main():

    # create form

    cform = CreateTask(prefix='cform')

You create a variable cform from the CreateTask object.

Then, further in your main() function, you have this if statement:

# response

if cform.validate_on_submit() and cform.create.data:

    return createTask(cform)

cform is a CreateTask object made from flask_wtf.Form which does not have a method validate_on_submit().

I checked the API documentation, and the validate_on_submit() only comes from the class flask_wtf.FlaskForm and not flask_wtf.Form

So to solve this, in your classes.py file:

from flask_wtf import Form
from wtforms import TextField, IntegerField, SubmitField

class CreateTask(Form):
    title = TextField('Task Title')
    shortdesc = TextField('Short Description')
    priority = IntegerField('Priority')
    create = SubmitField('Create')

import FlaskForm instead of Form, then update your classes to use FlaskForm -

from flask_wtf import FlaskForm
from wtforms import TextField, IntegerField, SubmitField

class CreateTask(FlaskForm):
    title = TextField('Task Title')
    shortdesc = TextField('Short Description')
    priority = IntegerField('Priority')
    create = SubmitField('Create')

Hope this helps!