Python + Flask IV

Flask WTF

Install
pip install flask-wtf


Create form

• Create file in root path Ex. survey_form.py

from flask_wtf import Form

from wtforms.fields import StringField

# from flask.ext.wtf.html5 import URLField

from flask_wtf.html5 import URLField

from wtforms.validators import DataRequired, url

class SurveyForm(Form):

signum = StringField('signum')

comments = StringField('comments')

url = URLField('url', validators=[DataRequired(), url()])

In controller  app.py

 Import the Form, it takes the file name

• from survey_form import SurveyForm

@app.route('/survey_wtf', methods=['GET', 'POST'] )

def survey_wtf():

form = SurveyForm()

if form.validate_on_submit():

# url = form.url.data

signum = form.signum.data

comments = form.comments.data

flash("Survey answered from '{}'".format(signum))

else :

flash("Error")

return render_template('survey_form.html', title_obj=Title(),form=form)

In the view

• include always       {{form.hidden_tag()}}
• define attributes                  {{form.signum(size=10)}}
• handle errors

 <p {% if form.signum.errors %} class="error" {% endif%} >

                Signum

                {{form.signum(size=10)}}

            </p>

Complete code:

 <form action="" method="POST">

    {{form.hidden_tag()}}

        <article>

            <p {% if form.signum.errors %} class="error" {% endif%} >

                Signum

                {{form.signum(size=10)}}

            </p>

            <p>

            <ul>

            {% for error in form.signum.errors %}

            <li>{{error}}</li>

            {% endfor%}

            </ul>

            </p>

            <!-- <p>

                Problem

                <input type="text" name="engineer">

            </p> -->

            <p> Comments

                {{form.comments(size=10)}}

            </p>

            <p>

                <button type="submit">Send Survey</button>

            </p>

        </article>

    </form>

Custom validation

In the class override the method validate

class SurveyForm(Form):

signum = StringField('signum',  validators=[DataRequired()])

comments = StringField('comments')

# url = URLField('url', validators=[DataRequired(), url()])

def validate(self):

if not Form.validate(self):

return False

if not self.signum.data:

self.signum.data = "None"

return True