now I get your point...good example
On Sun, Jan 25, 2009 at 9:28 PM, David Kamenetz <kamene...@yahoo.ca> wrote:
>
> I finally got this working.
>
> My python module looked something like this:
>
> from google.appengine.ext.db import Key
> from google.appengine.api.datastore import Get, Put
>
> def edit_item(request, db_id):
>
> objKey = Key(str(db_id))
>
> if request.method == 'POST':
> objEntity = Get(objKey)
> for k, v in request.POST.iteritems():
> objEntity[k]=v
> Put(objEntity)
> return HttpResponseRedirect('/')
>
> query = TestModel.get(objKey)
> return render_to_response('edit.html', ({'modify_data': query,}))
>
> My HTML looked something like this:
>
> <form method="POST" action="." enctype="multipart/form-data">
> Title: <input type="text" name="title"
> value="{{modify_data.field1}}"/>
> Text: <input type="text" name="txt" value="{{modify_data.field2}}"/>
>
> <input type="submit"/>
> </form>
>
> Many thanks to Bill!
>
> On Jan 24, 10:32 pm, David Kamenetz <kamene...@yahoo.ca> wrote:
> > Thanks Bill, that was helpful. I had been browsing datastore.py in the
> > SDK, but I wasn't quite sure how to use it. Your solution gave me a
> > lot of ideas.
> >
> > Regards,
> > David
> >
> > On Jan 24, 7:11 pm, Bill <billk...@gmail.com> wrote:
> >
> > > Hi David,
> >
> > > On Jan 24, 8:39 am, David Kamenetz <kamene...@yahoo.ca> wrote:
> >
> > > > However, if the user only enters/changes, say, the txt field on the
> > > > form I only POST the txt field to the server. I don't send all the
> > > > fields. My POST only has data for txt. If I use the code above on an
> > > > existing entity, it will erase the title property (formitem.title).
> >
> > > > Is there an elegant way to write only the txt element to the txt
> > > > property?
> >
> > > As far as I know, you can't write only one property when replacing an
> > > existing entity, but maybe there's something that can be done at the
> > > lowest levels just before going to the protocol buffer. (See
> > > datastore.py and datastore_pb.py in the SDK where entity dicts are
> > > being passed.)
> >
> > > I use POSTs to create new entities and PUTs to modify existing ones or
> > > store a new entity in a known url. With the PUTs, if there's an
> > > existing entity, you need to read it in and then selectively modify
> > > key/values depending on what's been passed from your form.
> >
> > > So creating new entities through POST is simple. Just set whatever
> > > property you want to set on model initialization, and all others are
> > > not stored.
> >
> > > You can automate the whole process by creating a Model you'll inherit
> > > from (I call mine SerializableModel), and create a method that
> > > iterates through all model properties, calls request.get() on them,
> > > and if the get isn't None (i.e., there's a value passed in from your
> > > form), you add that key/value to your entity dict. You later pass the
> > > entity dict as an initializer into your Model constructor.
> >
> > > For example:
> >
> > > def get_entity_dict(model_class, get_func):
> > > entity_dict = {}
> > > for prop_name, prop_class in model_class.properties().iteritems():
> > > value = get_func(prop_name)
> > > if value:
> > > entity_dict[prop_name] = model_class.deserialize
> > > (prop_class, value)
> > > return entity_dict
> >
> > > So in the above, get_func is set to:
> >
> > > get_func = lambda x : some_handler.request.get(x, default_value=None)
> >
> > > We only set key/value pairs in entity_dict for properties that are set
> > > in form.
> >
> > > The model_class.deserialize() is a routine that takes strings from the
> > > form and converts them into appropriate datastore objects.
> >
> > > So in your handler you'd have something like this in simplified form:
> >
> > > def post(self):
> > > get_func = lambda x : some_handler.request.get(x,
> > > default_value=None)
> > > props = get_entity_dict(MyModel, get_func)
> > > obj = MyModel(**props)
> > > obj.put()
> >
> > > For the PUT case, you read the entity first, set the entity_dict to
> > > the current entity values, and then do the above.
> >
> > > I might open source the model system I've created that does all this
> > > stuff.
> >
> > > -Bill
> >
>
--
Stay hungry,Stay foolish.
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