CODEWITHSUNDEEP
pythongoogle-app-enginegoogle-cloud-datastoreapp-engine-ndbendpoints-proto-datastore
pisquared
pisquared

Reputation: 21

Python endpoints_proto_datastore query by KeyProperty

I'm just starting out with AppEngine and using the endpoints_proto_datastore library. My problem: when I attempt to list all the PlaylistItems for a particular Playlist, the 'playlist' parameter in the query path seems to be ignored. I just retrieve all the PlaylistItems from all Playlists.

What am I doing wrong? I haven't been able to find any examples with two models, where the models are related by KeyProperty and queried via the path-element. I also don't understand why I don't see PlaylistItem.playlist in the datastore (unless it is part of the key).

These are the relevant Models and methods:

from endpoints_proto_datastore.ndb import EndpointsAliasProperty
from endpoints_proto_datastore.ndb import EndpointsModel

class Playlist(EndpointsModel):
    """Models an individual Playlist."""
    # fixed order
   _message_fields_schema = ('id', 'user', 'title', 'private', 'created')
    # actual stored information
    user = ndb.StringProperty(required=True, indexed=True)
    title = ndb.StringProperty(required=True, indexed=False)
    private = ndb.BooleanProperty(required=False, default=True, indexed=False)
    created = ndb.DateTimeProperty(required=False, auto_now_add=True, indexed=False)


class PlaylistItem(EndpointsModel):
    """Models a playlist item (appid)"""
    # fixed order
    _message_fields_schema = ('appid', 'inserted')
    # actual stored information
    appid = ndb.StringProperty(required=True, indexed=False)
    inserted = ndb.DateTimeProperty(required=False, auto_now_add=True, indexed=True)
    playlist = ndb.KeyProperty(required=True, kind=Playlist, indexed=True)

    def PlaylistSet(self, value):
        playlist = ndb.Key(Playlist, value)

    @EndpointsAliasProperty(setter=PlaylistSet, required=True)
    def playlist(self):
        playlist

and the relevant methods:

    @PlaylistItem.method(path='playlist/{playlist}/items', http_method='POST', name='playlist.items.put',
        request_fields=('playlist','appid'))
    def PlaylistItemPut(self, PlaylistItem):
        PlaylistItem.put()
        return PlaylistItem

    @PlaylistItem.query_method(path='playlist/{playlist}/items', name='playlist.items.list',
    query_fields=('playlist',),)
    def PlaylistItemList(self, query):
        return query # problem, I just retrieve all PlaylistItems

Upvotes: 1

Views: 178

Answers (1)

pisquared
pisquared

Reputation: 21

I changed the code based on the suggestions from Alex. It seems the most important bug I had was not using self.playlist from the PlaylistSet method. Afterwards I had the naming conflic that Alex pointed out. Below is the working code after all changes:

class PlaylistItem(EndpointsModel):
    """Models a playlist item (appid)"""
    # fixed order
    _message_fields_schema = ('appid', 'inserted')
    # actual stored information
    appid = ndb.StringProperty(required=True, indexed=False)
    inserted = ndb.DateTimeProperty(required=False, auto_now_add=True, indexed=True)
    playlist = ndb.KeyProperty(required=True, kind=Playlist, indexed=True)

    def PlaylistSet(self, value):
        self.playlist = ndb.Key(Playlist, value) # FIX: MUST use self.playlist here!

    @EndpointsAliasProperty(setter=PlaylistSet, required=True)
    def myplaylist(self): # renamed the method
        return playlist   # return the playlist

Also updated the Playlist API methods to use the new myplaylist name:

    @PlaylistItem.method(path='playlist/{myplaylist}/items', http_method='POST', name='playlist.items.put',
        request_fields=('myplaylist','appid')) # renamed request field
    def PlaylistItemPut(self, PlaylistItem):
        PlaylistItem.put()
        return PlaylistItem

    @PlaylistItem.query_method(path='playlist/{myplaylist}/items', name='playlist.items.list',
        query_fields=('myplaylist',),) # renamed request field
    def PlaylistItemList(self, query):
        return query

I can also see the playlist "column" in the Datastore viewer (as you would expect, previously it was not set).

Upvotes: 1

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