Flask-WT Form: How to pass additional parameters for form

Solution

class CustomForm(Form):

    def __init__(self, formdata=None, obj=None, prefix="", data=None, meta=None, **kwargs):
        self.form_class = kwargs.pop('form_class', None)
        super(CustomForm, self).__init__(formdata, obj, prefix, data, meta, **kwargs)

from flask import Flask, render_template_string
from wtforms import Form, StringField

app = Flask(__name__)


class CustomForm(Form):

    def __init__(self, formdata=None, obj=None, prefix="", data=None, meta=None, **kwargs):
        self.form_class = kwargs.pop('form_class', None)
        super(CustomForm, self).__init__(formdata, obj, prefix, data, meta, **kwargs)


class TestForm(CustomForm):
    first_name = StringField()


html_template = '''
    
        {{ form.first_name }}
    
'''


@app.route('/')
def custom_form():
    _form = TestForm(form_class='form-class')
    return render_template_string(html_template, form=_form)


if __name__ == '__main__':
    app.run()