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 <[email protected]> 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 <[email protected]> wrote:
>
> > Hi David,
>
> > On Jan 24, 8:39 am, David Kamenetz <[email protected]> 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
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