CODEWITHSUNDEEP
flask
gambit2017
gambit2017

Reputation: 277

Flask - difference between methods for detecting 'POST'?

When i want to check if form data was submitted using POST, what is the difference between:

if request.method == 'POST'

And:

if form.validate_on_submit():

?

Upvotes: 1

Views: 880

Answers (1)

6ones
6ones

Reputation: 62

form.validate_on_submit() does what the request.method == 'POST' and more, so it's like a more advanced function.

form.validate_on_submit() is a function implemented in the "Flask-WTF" package, which is a shortcut to two functions: form.is_submitted() and form.validate() 

    def validate_on_submit(self):
        """Call :meth:`validate` only if the form is submitted.
        This is a shortcut for ``form.is_submitted() and  form.validate()``.
        """
        return self.is_submitted() and self.validate()

Note: The self.validate() is implemented by the "wtforms" package, which "Flask-WTF" uses the wtforms.Form as a base class for the flask_wtf.FlaskForm or the flask_wtf.Form which is deprecated.

Going deeper, what the self.is_submitted() function does is return a _is_submitted() boolean function:

def is_submitted(self):
    """Consider the form submitted if there is an active request and
    the method is ``POST``, ``PUT``, ``PATCH``, or ``DELETE``.
    """

    return _is_submitted()

And the _is_submitted() is defined as:

def _is_submitted():
    """Consider the form submitted if there is an active request and
    the method is ``POST``, ``PUT``, ``PATCH``, or ``DELETE``.
    """

    return bool(request) and request.method in SUBMIT_METHODS

The SUBMIT_METHODS constant is defined this way:

SUBMIT_METHODS = set(('POST', 'PUT', 'PATCH', 'DELETE'))

From the snippets, you can see that the form.validate_on_submit() handles the request.method and does more.

So if you are making use of the Flask-WTF package and your form is inheriting from the "FlaskForm" class, it's better to use form.validate_on_submit() than request.method == 'POST', as the former handles both verifying if a form is submitted and if the post request made is also valid.

Upvotes: 1

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