ParseQuery with ParseRelation

[ghost]

Hey,

I wanted to do a live query operation with a ParseRelation.

Here is my code:
ParseRelation<ParseObject> relation = channel.getRelation("messages");
ParseQuery<ParseObject> query = relation.getQuery();
query.whereEqualTo("messageText", "test");

With this code I don´t get any response from server. If I do a query
without a relation, it works well.

Is ParseRelation not possible in association with LiveQuery?

Thanks in advance.

[jhansche]

What's the actual structure of your data object(s)? And what's the JSON query that is being sent in the subscribe call? And does it work if you use query.findInBackground(new FindCallback ...);?

query.findInBackground() will try to locate the object(s) that match that query. If you get no data from that query, then you will also get no response in the LiveQuery.

[ghost]

I did execute the query with query.findInBackground(new FindCallback ...); and I got all objects, which are exists in the relation.

This is the data structure:
Class Channel:
This object contains a ParseRelation to class "Message".
The column is named "messages".

Class Message:
A message has a "messageText" and an owner (ParseUser pointer).

My subscribtion: subscriptionHandling = liveQueryClient.subscribe(query);

So with FindInBackground I get all objects in the relation, but with live query it is not working.
Did you tried a subscription to a ParseRelation?

[jhansche]

No, I haven't - just wanted to address the first part before looking, because if the query itself doesn't work, the LiveQuery can never possibly work :)

But according to parse-community/parse-server#2946, what you're asking for is not supported.

I have personally tested and used ParsePointer LiveQueries, and that does work. But apparently ParseRelation does not work on the server side yet.

One option: you may be able to change your objects so that instead of:

class Channel {
  ParseRelation<Message> getMessages() { return getRelation("messages"); }
}
class Message {}

you can change it so the Message has a pointer to the Channel instead:

class Channel { ... }
class Message {
  Channel getChannel() { return (Channel) getParseObject("channel"); }
}

and then your query and LiveQuery can use a Pointer reference, instead of a Relation reference:

Channel myChannelObj = ...;
ParseQuery<Message> messagesQuery = ParseQuery.getQuery(Message.class).whereEqualTo("channel", myChannelObj);
// messagesQuery.find() should still work same as before
liveQuery.subscribe(messagesQuery); // then should work also.

I know for certain that ParsePointer queries like this work, because my project does exactly this (and I made the commit that allows it to work correctly).

[jhansche]

Do you have the JSON string that is being sent for the ParseRelation query on subscribe? That might help track it down if the above isn't a solution.

But given that the parse server issue is still open, saying this is not supported, the above alternative may be your only option.

[ghost]

After I saw, that live query with ParseRelation is not working, I used the solution which you posted.
With this data model it works really well.

Thank you for your quick response. :)

[Edijae]

Is livequery on parserelation not yet supported?