How to validate html forms in python Flask?

Question

I have a HTML form inside a landing page and I want to send the forms data by ajax to /data rout.
The problem is validating this HTML form in backend.
I know about Flask WTF form but using this method will generate form on backend which is not my case.

from flask import Flask, request, url_for
...
@app.route("/data", methods=["GET", "POST"])
def get_data():
if request.method == "POST":
    username = request.form["username"]
    ...

My html form:

<form method="POST" action="">
<input type="text" name="username">
<input type="submit" value="Send">
</form>

One hard way is to validate every field using regex and write several if conditions for them. I'm wondering for easier way?

How do you want to validate the form exactly? What checks do you want to do? — glhr
– glhr, Commented Apr 20, 2019 at 9:35
But I don't want to user regex for all inputs. It must be a better way? — Mohammad Ghonchesefidi
– Mohammad Ghonchesefidi, Commented Apr 20, 2019 at 9:49
If you don't want to use the validation methods provided by Flask-WTF you will need to write them yourself, indeed. Is there a specific reason you don't want to use Flask-WTF? — MrLeeh
– MrLeeh, Commented Apr 20, 2019 at 10:00
I would just import the WTForms validators you need and run them on your input yourself without creating a form. At least it saves you from creating your own regex for email, phone, date, etc. — EAW
– EAW, Commented Apr 20, 2019 at 17:30

Attack68 · Accepted Answer · 2019-04-20 19:54:26Z

Using Webargs

from webargs import flaskparser, fields

FORM_ARGS = {
    'email': fields.Email(required=True),
    'username': fields.Str(required=True),

@app.route("/data", methods=["GET", "POST"])
def get_data():
    if request.method == "POST":
        parsed_args = flaskparser.parser.parse(FORM_ARGS, request)

But as long as you know the format of the incoming data you can still use WTFs for capturing the posted info (you dont need to render WTForms on a page for it to work), for example:

# import blurb    

class Form(FlaskForm):
    username = StringField('Username', validators=[InputRequired()])
    email = EmailField('Email', validators=[InputRequired(), Length(4, 128), Email()])

@app.route("/data", methods=["GET", "POST"])
def get_data():
    if request.method == "POST":
        form = Form()  # will register fields called 'username' and 'email'.
        if form.validate_on_submit():
            # do something

Collectives™ on Stack Overflow

How to validate html forms in python Flask?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related