Retrieving form date with Flask Requests

I've been using Flask's requests to retrieve data from a form. It's been working perfectly except I can't get the date input type from the html forms to work

This is the code that I thought would get the data back:

dob = request.form['dob']

This is how the section of the form looks

Date of Birth <input type="date" class="" name="dob" value="{{request.form.dob}}"><br />

If I change the input type from date to text then it works without problem, but I can't seem to get the date input to work.