How can I create custom form classes in Flask-WTF?

How can I create custom form classes in Flask-WTF?

To create custom form classes in Flask-WTF, you can subclass the FlaskForm class and define your fields.

Can you show me an example of a custom form class?

Sure! Here's a simple example:

from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField

class MyForm(FlaskForm):
    name = StringField('Name')
    submit = SubmitField('Submit')

How do I validate the fields in my custom form?

You can add validators to your fields. For example:

from wtforms.validators import DataRequired

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

What if I want to add custom validation logic?

You can define a custom validator function and use it in your field. Here's an example:

def validate_name(form, field):
    if len(field.data) < 3:
        raise ValidationError('Name must be at least 3 characters long.')

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