Flask WTF



  • WTF stands for WT Forms.
  • To provide the interactive user interface for the user.
  • It is a built-in module of the flask which provides an alternative way of designing forms in the flask web applications.

Why WTF Useful ?

  • The form elements are sent along with the request object from the client side to the server side. Server-Side script must recreate the form elements since there's no direct mapping between the client side form elements and therefore the variables to be used at the server side.
  • There is no way to render the HTML form data at real time.
  • The WT Forms may be a flexible, form rendering, and validation library wont to provide the interface.

Install Flask-WTF

  • To use the WT forms, we need to install the flask-wtf library which can be installed using pip installer.
$ pip install flask-wtf   

Standard Form Fields are listed:

SN Form Field Description
1 BooleanField It is used to represent the checkbox HTML form element.
2 DecimalField It is used to represent the text field to display the numbers with decimals.
3 BooleanField It is used to represent the checkbox HTML form element.
4 IntegerField It is used to represent the text field to display the integer values.
5 RadioField It is used to represent the radio button HTML form element.
6 selectField It is used to represent the select form element.
7 TextAreaField It is used to represent text area form element.
8 PasswordField It is used to take the password as the form input from the user..
9 SubmitField It provides represents the <input type='submit' value='Submit'> html form element.

Sample code

Here we will create a form using flask WTF module.


from flask_wtf import Form 
from wtforms import TextField, IntegerField, TextAreaField, SubmitField, RadioFied, SelectField  
from wtforms import validators, ValidationError  
class ContactForm(Form): 
   name = TextField("Candidate Name ",[validators.Required("Please enter your nme.")])  
  Gender = RadioField('Gender', choices = [('M','Male'),('F','Female')])  
   ddress = TextAreaField("Address")  
 email = TextField("Email",[validators.Required("Please enter your email address.),  
   alidators.Email("Please enter your email address.")])  
   Age = IntegerField("Age") 
language = SelectField('Programming Languages', choices = [('java', 'Java'),('py' 'Python')])  
   submit = SubmitField("Submit")  


from flask import Flask, render_template, request, flash  
from forms import ContactForm  
app = Flask(__name__)  
app.secret_key = 'development key'  
@app.route('/contact', methods = ['GET', 'POST'])  
def contact():  
   form = ContactForm()  
   if form.validate() == False:  
      flash('All fields are required.')  
   return render_template('contact.html', formform = form)  
@app.route('/success',methods = ['GET','POST'])  
def success():  
   return render_template("success.html")  
if __name__ == '__main__':  
   app.run(debug = True)  


<!doctype html>  
      <h2 style = "text-align: center;">Registration Form</h2>  
      {% for message in form.name.errors %}  
         <div>{{ message }}</div>  
      {% endfor %}  
      {% for message in form.email.errors %}  
         <div>{{ message }}</div>  
      {% endfor %}  
      <form action = "http://localhost:5000/success" method = "POST">  
            {{ form.hidden_tag() }}  
            <div style = "font-size:18px;" font-weight:bold; margin-left:150px;>  
               {{ form.name.label }}<br>  
               {{ form.name }}  
               {{ form.Gender.label }} {{ form.Gender }}  
               {{ form.Address.label }}<br>  
               {{ form.Address }}  
               {{ form.email.label }}<br>  
               {{ form.email }}  
               {{ form.Age.label }}<br>  
               {{ form.Age }}  
               {{ form.language.label}}<br><br>  
               {{ form.language }}  
               {{ form.submit }}  


<!DOCTYPE html>  
<h1>Form posted successfully</h1>  




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