Flask: differences between request.form["xxxxx"], request.form.get("xxxxxx") and request.args.get("xxxxx")?

Question

What are the differences between flask.request.form["xxx"] , flask.request.form.get("xxx") and flask.request.args.get("xxx") ?

I have this question because I am using flask-login to handle authentication.
In particular in the following code (taken from the flask-login github page), I don't understand why with req.form.get("email"), email is None, while with req.form["email"], email hasn't a value. Here's the code.

@login_manager.request_loader
def request_loader(req):
    email = req.form.get('email')
    if email not in users:
        return

    user = User()
    user.id = email

    # DO NOT ever store passwords in plaintext and always compare password
    # hashes using constant-time comparison!
    user.is_authenticated = req.form['pw'] == users[email]['pw']

    return user

`req.form` is a dictionary. `get` returns `None` if key not found, whereas the `[]` access throws `KeyError` — Jean-François Fabre, Oct 01 '16 at 12:13
`request.args` are `GET` parameters, `request.form` are data submitted via `POST` form — yedpodtrzitko, Oct 01 '16 at 12:22
Thank you all for answers, I have understood the differences. Maybe the most helpful is the @Jean-FrançoisFabre answer — Miles, Oct 01 '16 at 12:40

score 4 · Accepted Answer · answered Oct 01 '16 at 13:59

The proper use-case get() is to return a default value when the key you are looking for doesn't exist in a dictionary.

For example, if you have a dictionary d such that :

d = {'foo': 'bar'}

Doing the following will return None:

d.get('baz', None)

While doing the following will throw an exception:

d['baz']

Flask: differences between request.form["xxxxx"], request.form.get("xxxxxx") and request.args.get("xxxxx")?

1 Answers1