In Flask convert form POST object into a representation suitable for mongodb

Question

I am using Flask and MongoDB. I am trying to convert the content of request.form into something suitable for saving via PyMongo. It seems like something that should come up often enough to have a ready-made solution.

So what Flask give me is something like:

ImmutableMultiDict([('default', u''), ('required': u'on'), ('name', u'short_text'), ('name', u'another'), ('submit', u'Submit')])

And what I am looking to get is something close to this:

{
  'default': '',
  'name': ['short_text', 'another'],
  'required': true
}

Answer 1

>>> from werkzeug.datastructures import ImmutableMultiDict
>>> imd = ImmutableMultiDict([('default', u''), ('required', u'on'), ('name', u'short_text'), ('name', u'another'), ('submit', u'Submit')])
>>> imd.to_dict(flat=False)
>>> {'default': [''], 
'name': ['short_text', 'another'],
'required': ['on'],
'submit': ['Submit']}

.to_dict(flat=False) is the thing to keep in mind. See the relevant documentation

Answer 2

The Flask ImmutableMultiDict data structure has a built in to_dict method.

This knowledge in addition to the Flask request object form property being an ImmutableMultiDict allows for simple handling of a form POST request to MongoDB.

See below for a naive example:

from flask import request

@app.route('/api/v1/account', methods=['POST'])
def create_account():
    """Create user account"""
    account_dict = request.form.to_dict()

    db.account.insert_one(account_dict)

Answer 3

You can use werkzeug's getlist to write code like this

data = dict((key, request.form.getlist(key)) for key in request.form.keys())

Now each key of data would be a list which would contain 1 more element. To get results exactly in your format do this

data = dict((key, request.form.getlist(key) if len(request.form.getlist(key)) > 1 else request.form.getlist(key)[0]) for key in request.form.keys())

Now this is inefficient because for each key there are 3 calls to request.form.getlist(key). You can write a loop and get around it.