how tornado can be used to show error on frontend

Question

Here is my python file for the contact form of the website. the main file is getting the data and sending it to the database.

 #main.py
    class next(tornado.web.RequestHandler):
    def get(self):
        self.render("contact.html")
    async def post(self):
        form = contact(self.request.arguments)
        name_ = form.data["name"]
        phone_ = form.data["phone"]
        email_ = form.data["email"]
        message_ = form.data["message"]
        image_ = form.data["pic"]
        print(name_, phone_, email_, message_, image_)

        try:

            dbsend = TestModel.create(name=name_, phone=phone_, email=email_,message=message_,image=image_)
            dbsend.save()
            print('done')
            self.render("contact.html")
        except:
            print('not done')

this is the file where I think all validation code belongs

validation.py

from wtforms import *
from wtforms_tornado import Form
class contact(Form):
    name= StringField('name',[validators.required()])
    phone = StringField('phone', [validators.Length(min=4, message="too Short")])
    email = StringField('email', [validators.Length(min=4, message="too Short")])
    message = StringField('message', [validators.Length(min=4, message="too Short")])
    pic = StringField('pic', [validators.Length(min=4, message="too Short")])

This is the HTML page containing the form.

contact.html

 <div class="row">
    <div class="col-lg-8 mb-4">
      <h3>Send us a Message</h3>
      <form name="sent" action="/contact" method="post" id="cForm" >
        <div class="control-group form-group">
          <div class="controls">
            <label>Full Name:</label>
            <input type="text"  name="name" >
            <p class="help-block"></p>
          </div>
        </div>
        <div class="control-group form-group">
          <div class="controls">
            <label>Phone Number:</label>
            <input  name="phone" >
          </div>
        </div>

        <div class=" ">
          <div class="">
            <label>Email Address:</label>
            <input   name="email">
          </div>
        </div>
        <div class="control-group form-group">
          <div class="controls">
            <label>Message:</label>
            <textarea rows="10" cols="100"  name="message" ></textarea>
          </div>
        </div>
        <div class="control-group form-group">
          <div class="controls">
            <label>Image:</label>
            <input type="file" name="pic" accept="image/*">
          </div>
        </div>
        <div id="success"></div>
        <!-- For success/fail messages -->
        <button type="submit" class="btn btn-primary" id="sendMessageButton">Send Message</button>
      </form>

    </div>

How can I put validations on email phone etc and show the error on the front end?

Answer 1

As it all stated it WTForms documentation, you can use validate() method of a form-instance to run validators. All errors would be in the form.errors attribute. You can insert errors messages into a HTML page by using a templating engine.