Form validation with WTForms and and autofill SQLAlchemy model with form data in Flask

Question

I have a form that i have to validate and then save the data in the database. I have a SQLAlchemy model called Campaign which looks something like this

from flask.ext.sqlalchemy import SQLAlchemy

db = SQLAlchemy()
class Campaign(db.Model):
    __tablename__ = 'campaigns'

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50))
    priority = db.Column(db.SmallInteger)
    starts_at = db.Column(db.Date)
    ends_at = db.Column(db.Date)
    .... bla bla bla

Now i have a WTForm form for validation like this

from flask.ext.wtf import Form, TextField, IntegerField, DateField, Required, NumberRange
class CampaignForm(Form):

    def date_validation(form, field):
        #some validation on date

    name = TextField(validators=[Required()])
    priority = IntegerField(validators=[Required(), NumberRange(min=1,max=100)])
    start_date = DateField(validators=[Required(), date_validation])
    end_date = DateField(validators=[Required(), date_validation])
    ... bla bla bla

Now to validate and save the form data, I can do something like this is my view

code in Flask

class CampaignsView(MethodView):
    def post(self):
        """
        For creating a new campaign
        """
        form = CampaignForm(request.form)
        if form.validate():
            campaign = Campaign(form.name.data, form.priority.data, and so on )
            session.add(campaign)

Now the above code is stupid because i have to hard-code every field name in the view. Is there some other way where i can fill the fields of my model with form fields? Thanks

Alexander Jung-Loddenkemper · Accepted Answer · 2013-01-23 18:46:42Z

8

You can use the .populate_obj method like this:

if form.validate_on_submit():
    campaign = Campaign()
    form.populate_obj(campaign)

Also check out the docs on this.

answered Jan 23, 2013 at 18:46

Alexander Jung-Loddenkemper

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2 Comments

famargar Over a year ago

That's great. And is there any way to avoid generating the same logical class once for the form, and once for the database? Can one generate one class for both?

Alexander Jung-Loddenkemper Over a year ago

@famargar not sure whether I understand your question?

Mohammad Efazati · Accepted Answer · 2013-01-23 14:13:16Z

4

there is wtforms extension for sqlalachemy:

WTForms Documentation -> http://wtforms.simplecodes.com/docs/0.6.1/ext.html#module-wtforms.ext.sqlalchemy

also somethings can help you

kvesteri/wtforms-alchemy · GitHub -> https://github.com/kvesteri/wtforms-alchemy
Automatically create a WTForms Form from model | Flask (A Python Microframework) -> http://flask.pocoo.org/snippets/60/

from links:

from flaskext.wtf import Form
from wtforms.ext.appengine.db import model_form
from models import MyModel

MyForm = model_form(MyModel, Form)

answered Jan 23, 2013 at 14:13

Mohammad Efazati

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2 Comments

lovesh Over a year ago

In (this)[flask.pocoo.org/snippets/60/] approach i have to pass validators in the field_args argument of model_form. Cant i use my form class CampaignForm?

Mohammad Efazati Over a year ago

@lovesh no, you can extend data with field_args.

Michael come lately · Accepted Answer · 2017-06-24 19:53:58Z

0

You can also do something like this:

if request.method == 'POST' and form.validate() == True:
    create new user

and send the user to a desired page

edited Jun 24, 2017 at 19:53

Michael come lately

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answered Jun 23, 2017 at 19:46

Fon Desmond

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