How can I create custom form classes in WTForms?

How can I create custom form classes in WTForms?

To create custom form classes in WTForms, you can subclass the Form class and define your fields.

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

Sure! Here's a simple example:

from wtforms import Form, StringField, PasswordField, validators

class CustomForm(Form):
    username = StringField('Username', [validators.Length(min=4, max=25)])
    password = PasswordField('Password', [validators.DataRequired()])

What if I want to add custom validation?

You can add custom validation by defining a method in your form class and using the @validates decorator. For example:

from wtforms import ValidationError

class CustomForm(Form):
    # ... fields here ...

    @validates('username')
    def validate_username(self, field):
        if field.data == 'admin':
            raise ValidationError('Username cannot be admin.')

Can I use custom widgets with my form fields?

Yes, you can use custom widgets by specifying the widget parameter when defining your fields. For example:

from wtforms.widgets import TextInput

class CustomForm(Form):
    username = StringField('Username', widget=TextInput(attrs={'class': 'custom-class'}))