PUT /datastores/id: Update an existing item.

def update(self, id):
        """PUT /datastores/id: Update an existing item."""
        # url('DataStores', id=ID)
        content = request.environ['wsgi.input'].read(int(request.environ['CONTENT_LENGTH']))
        content = content.decode('utf8')
        content = simplejson.loads(content)        
        result = meta.Session.query(DataStore).get(id)
        result.name = content['name']
        result.type = content['type']
        result.ogrstring = content['ogrstring']
        meta.Session.commit()
        response.status = 201