Yesterday I ran into an interesting quirk with Django's QueryDict object and the normal dictionary update() method. Normally the update method will allow you to merge two dictionary or dictionary like objects but because the QueryDict internally holds it's values as lists you get some unexpected behavior.
For instance with a normal dictionary you can do this:
| >> x = {"name": "Ian"} | |
| >> x.update({"age":27}) | |
| >> x | |
| {'age': 27, 'name': 'Ian'} |
But with Django's request.POST and request.GET QueryDict objects the internal representation of the values are list so you get unexpected behavior even though normally accessing the value by key does not give you a list:
| >> x = {"job":"programmer"} | |
| >> request.POST | |
| <QueryDict: {u'name': [u'Ian'], u'age': [u'27']}> | |
| >> request.POST['name'] | |
| u'Ian' | |
| >> request.POST['age'] | |
| u'27' | |
| >> x.update(request.POST) | |
| >> x | |
| {u'name': [u'Ian'], u'age': [u'27'], 'job': 'programmer'} | |
| >> x['name'] | |
| [u'Ian'] | |
| >> x['age'] | |
| [u'27'] |