How to query and include parent object in child query

[GursheeshSingh]

I have two classes -

PollLike and Poll

The PollLike is like child of the poll object

class Poll extends ParseObject implements ParseCloneable {
  Poll.clone(String className, PollType pollType) : this(className, pollType);

  @override
  clone(Map map) => Poll.clone(className, pollType)..fromJson(map);

  Poll(this.className, this.pollType) : super(className);

  String className;
  PollType pollType;

  String get question => get<String>("question");

  String get coverImage => get<String>("coverImage");

  String get optionsType => get<String>("optionsType");

  int get totalNumberOfVotes => get<int>("totalNumberOfVotes");

  int get numberOfLikes => get<int>("numberOfLikes");

  List<dynamic> get options => get<List<dynamic>>("options");

  List<dynamic> get tags => get<List<dynamic>>("tags");

  Map<String, dynamic> get votes => get<Map<String, dynamic>>("votes");

  ///Name of user
  String get userName => get<String>("userName");

  String get expiryDateTime => get<String>("expiryDateTime");

  set question(String question) => set<String>("question", question);

  set coverImage(String coverImage) => set<String>("coverImage", coverImage);

  set optionsType(String optionsType) =>
      set<String>("optionsType", optionsType);

  set totalNumberOfVotes(int totalNumberOfVotes) =>
      set<int>("totalNumberOfVotes", totalNumberOfVotes);

  set numberOfLikes(int numberOfLikes) =>
      set<int>("numberOfLikes", numberOfLikes);

  ///Name of user
  set userName(String userName) => set<String>("userName", userName);

  set expiryDateTime(String expiryDateTime) =>
      set<String>("expiryDateTime", expiryDateTime);

  set options(List<dynamic> options) => set<List<dynamic>>("options", options);

  set tags(List<dynamic> tags) => set<List<dynamic>>("tags", tags);

  set votes(Map<String, dynamic> votes) =>
      set<Map<String, dynamic>>("votes", votes);
}

class PollLike extends ParseObject implements ParseCloneable {
  PollLike.clone(String className, PollType pollType)
      : this(className, pollType);

  @override
  clone(Map map) => PollLike.clone(className, pollType)..fromJson(map);

  PollLike(this.className, this.pollType) : super(className);

  String className;
  PollType pollType;

  String get userId => get<String>("userId");

  String get pollId => get<String>("pollId");

  Poll get parent => get<Poll>("parent");

  set userId(String userId) => set<String>("userId", userId);

  set pollId(String pollId) => set<String>("pollId", pollId);

  set userName(String userName) => set<String>("userName", userName);

  set userProfilePicture(String userProfilePicture) =>
      set<String>("userProfilePicture", userProfilePicture);

  set parent(Poll parent) => set<Poll>("parent", parent);
}

Each class represents two classes in the Actual database.

Poll - OfficialPolls and UserPolls
PollLike - OfficialPollLikes and UserPollLikes

Now I save a OfficialPollLike with an official poll -

OfficialPollLike stores a pointer to the OfficialPoll object

Now, I want to retrieve OfficialPollLikes of a particular user with the Poll details already included in the response-

  QueryBuilder queryBuilder =
      QueryBuilder(PollLike("OfficialPollLikes", PollType.OFFICIAL))
        ..orderByDescending("_created_at")
        ..setLimit(PollLikesProvider.LIMIT)
        ..includeObject(["parent"]);

Here is the response-

flutter: {"className":"OfficialPollLikes","objectId":"T8wVTurJef","createdAt":"2020-04-17T11:17:12.026Z","updatedAt":"2020-04-17T11:17:12.026Z","userId":"3g3lk4M6Xl","pollId":"5e96e1d47b37522678375591","parent":{"__type":"Pointer","className":"OfficialPolls","objectId":"5e96e1d47b37522678375591"}}
flutter: {"className":"OfficialPollLikes","objectId":"AO5g5CAJFx","createdAt":"2020-04-17T11:17:08.647Z","updatedAt":"2020-04-17T11:17:08.647Z","userId":"3g3lk4M6Xl","pollId":"5e96e1e57b37522678375592","parent":{"__type":"Pointer","className":"OfficialPolls","objectId":"5e96e1e57b37522678375592"}}

It does not contain any fields of the Poll class except the pointer.
I am also new to Pointers and Relation on Parse SDK.

[fischerscode]

In your screenshot the pointer is called "_p_parent" in your query it's called "parent".
Please try this:

QueryBuilder queryBuilder =
      QueryBuilder(PollLike("OfficialPollLikes", PollType.OFFICIAL))
        ..orderByDescending("_created_at")
        ..setLimit(PollLikesProvider.LIMIT)
        ..includeObject(["_p_parent"]);

[GursheeshSingh]

Output:

flutter: {"className":"OfficialPollLikes","objectId":"T8wVTurJef","createdAt":"2020-04-17T11:17:12.026Z","updatedAt":"2020-04-17T11:17:12.026Z","userId":"3g3lk4M6Xl","pollId":"5e96e1d47b37522678375591","parent":{"__type":"Pointer","className":"OfficialPolls","objectId":"5e96e1d47b37522678375591"}}
flutter: {"className":"OfficialPollLikes","objectId":"AO5g5CAJFx","createdAt":"2020-04-17T11:17:08.647Z","updatedAt":"2020-04-17T11:17:08.647Z","userId":"3g3lk4M6Xl","pollId":"5e96e1e57b37522678375592","parent":{"__type":"Pointer","className":"OfficialPolls","objectId":"5e96e1e57b37522678375592"}}

No effect.

[fischerscode]

Have you tried to query manually through the rest API?

[GursheeshSingh]

Yes I tried that and it looks like it works using REST API.

Thank you.

Here is the URL-
http://localhost:1337/parse/classes/OfficialPollLikes?include=parent

Here is the response-

{
    "results": [
        {
            "objectId": "AO5g5CAJFx",
            "userId": "3g3lk4M6Xl",
            "pollId": "5e96e1e57b37522678375592",
            "parent": {
                "objectId": "5e96e1e57b37522678375592",
                "question": "Who is the best player? 3",
                "coverImage": "https://i.pinimg.com/originals/45/54/a1/4554a1c1f17cc22d7c40960d507fa717.png",
                "optionsType": "OptionType.text",
                "options": [
                    {
                        "optionNumber": 1,
                        "text": "Messi"
                    },
                    {
                        "optionNumber": 2,
                        "text": "Ronaldo"
                    }
                ],
                "tags": [
                    "messi",
                    "ronaldo",
                    "fcbarcelona",
                    "juventus",
                    "realmadrid"
                ],
                "totalNumberOfVotes": 51,
                "votes": {
                    "1": 36,
                    "2": 15
                },
                "createdAt": "2020-04-12T12:54:59.000Z",
                "updatedAt": "2020-04-17T11:17:08.843Z",
                "numberOfLikes": 7,
                "expiryDateTime": "2020-04-20T12:54:59.000Z",
                "__type": "Object",
                "className": "OfficialPolls"
            },
            "createdAt": "2020-04-17T11:17:08.647Z",
            "updatedAt": "2020-04-17T11:17:08.647Z"
        },
        {
            "objectId": "T8wVTurJef",
            "userId": "3g3lk4M6Xl",
            "pollId": "5e96e1d47b37522678375591",
            "parent": {
                "objectId": "5e96e1d47b37522678375591",
                "question": "Who is the best player? 2",
                "coverImage": "https://i.pinimg.com/originals/45/54/a1/4554a1c1f17cc22d7c40960d507fa717.png",
                "optionsType": "OptionType.image",
                "options": [
                    {
                        "optionNumber": 1,
                        "image": "https://thumbor.forbes.com/thumbor/fit-in/416x416/filters%3Aformat%28jpg%29/https%3A%2F%2Fspecials-images.forbesimg.com%2Fimageserve%2F5cfea7bb4c687b0008593c0a%2F0x0.jpg%3Fbackground%3D000000%26cropX1%3D1554%26cropX2%3D2474%26cropY1%3D240%26cropY2%3D1159",
                        "text": "Messi"
                    },
                    {
                        "optionNumber": 2,
                        "image": "https://i.pinimg.com/originals/d6/fe/c1/d6fec1cc149ac7fac63cef3abec08a6e.jpg",
                        "text": "Ronaldo"
                    }
                ],
                "tags": [
                    "messi",
                    "ronaldo",
                    "fcbarcelona",
                    "juventus",
                    "realmadrid"
                ],
                "totalNumberOfVotes": 53,
                "votes": {
                    "1": 37,
                    "2": 16
                },
                "createdAt": "2020-04-10T12:54:59.000Z",
                "updatedAt": "2020-04-17T11:17:12.216Z",
                "numberOfLikes": 5,
                "expiryDateTime": "2020-04-20T12:54:59.000Z",
                "__type": "Object",
                "className": "OfficialPolls"
            },
            "createdAt": "2020-04-17T11:17:12.026Z",
            "updatedAt": "2020-04-17T11:17:12.026Z"
        }
    ]
}

This is what I using hoping would be the response using the SDK.

Now this a bug in the Parse SDK right?

[fischerscode]

As the rest API works, it has to be a problem with the SDK, I think.

Could you please add

print('http://localhost:1337/parse/classes/OfficialPollLikes?${queryBuilder.buildQuery()}');

after your

  QueryBuilder queryBuilder =
      QueryBuilder(PollLike("OfficialPollLikes", PollType.OFFICIAL))
        ..orderByDescending("_created_at")
        ..setLimit(PollLikesProvider.LIMIT)
        ..includeObject(["parent"]);

and try to query the printed URL through the REST API?
This will show us, if there is a problem with the generated URL.

[GursheeshSingh]

Here is the output:

http://localhost:1337/parse/classes/OfficialPollLikes?where={}&order=-_created_at&limit=10&include=parent

However when I use the generated Url in Postman:

The response includes the parent details

[fischerscode]

Please try this:

  QueryBuilder queryBuilder =
      QueryBuilder(ParseObject("OfficialPollLikes"))
        ..orderByDescending("_created_at")
        ..setLimit(PollLikesProvider.LIMIT)
        ..includeObject(["parent"]);

It might be related to your custom class.

EDIT:
I've also noticed this: Poll get parent => get<Poll>("parent"); As far as I know, you wont get Objects of type Poll back, jet. See #350 (comment).

[GursheeshSingh]

Tried the above query-

Still the same response with no details

Also got an exception-

type 'ParseObject' is not a subtype of type 'PollLike' in type cast

Also the method registerSubClass isn't defined for ParseCoreData.

What should I do for using subclasses?

[fischerscode]

Are you just calling queryBuilder.query() to query?

registerSubClass is currently not available in this repo. I am working on such a feature, but as it is quite a huge change, we decided to add it after I have used/tested it for a while. (#350 (comment))
If you want, feel free to use it now already, but there might be bugs.

Edit:
Are you using the current released version of the SDK (1.0.26) or 1.0.27 or something older?

Edit2:

Also got an exception-

type 'ParseObject' is not a subtype of type 'PollLike' in type cast

As the query currently does not know about PollLike, this makes sens.

[GursheeshSingh]

Yup just calling queryBuilder.query();

I am using version - 1.0.26

[fischerscode]

I might have found the problem...
The debug message never contains the included data although the data got transmitted.
If you start the debugger and have a lock into the ParseResponse, you should see the included data.

[GursheeshSingh]

You are right.

I guess it is because of the Poll type.

Is there any way to handle that?

[fischerscode]

Please try this query again:

  QueryBuilder queryBuilder =
      QueryBuilder(PollLike("OfficialPollLikes", PollType.OFFICIAL))
        ..orderByDescending("_created_at")
        ..setLimit(PollLikesProvider.LIMIT)
        ..includeObject(["parent"]);

and have a look into the object trough the debugger.

Inside the debugger you should see the included object.

[GursheeshSingh]

I changed the Poll type in PollLike to ParseObject

ParseObject get parent => get<ParseObject>("parent");
set parent(ParseObject parent) => set<ParseObject>("parent", parent);

Some checks

print(officialPollLike.parent.toString());

print(officialPollLike.parent.get("question"));
            
print(officialPollLike.parent.runtimeType);

Output:

{"className":"OfficialPolls","objectId":"5e96e1e57b37522678375592","createdAt":"2020-04-12T12:54:59.000Z","updatedAt":"2020-04-17T11:17:08.843Z","question":"Who is the best player? 3","coverImage":"https://i.pinimg.com/originals/45/54/a1/4554a1c1f17cc22d7c40960d507fa717.png","optionsType":"OptionType.text","options":[{"optionNumber":1,"text":"Messi"},{"optionNumber":2,"text":"Ronaldo"}],"tags":["messi","ronaldo","fcbarcelona","juventus","realmadrid"],"totalNumberOfVotes":51,"votes":{"1":36,"2":15},"numberOfLikes":7,"expiryDateTime":"2020-04-20T12:54:59.000Z"}
flutter: Who is the best player? 3
flutter: ParseObject

It has the ParseObject with details and I can access it using
.get(key)

I created a class for OfficialPolls

class OfficialPoll extends ParseObject implements ParseCloneable {
  OfficialPoll.clone() : this();

  @override
  clone(Map map) => OfficialPoll.clone()..fromJson(map);

  OfficialPoll() : super("OfficialPolls");

  String get question => get<String>("question");

  String get coverImage => get<String>("coverImage");

  String get optionsType => get<String>("optionsType");

  int get totalNumberOfVotes => get<int>("totalNumberOfVotes");

  int get numberOfLikes => get<int>("numberOfLikes");

  List<dynamic> get options => get<List<dynamic>>("options");

  List<dynamic> get tags => get<List<dynamic>>("tags");

  Map<String, dynamic> get votes => get<Map<String, dynamic>>("votes");

  ///Name of user
  String get userName => get<String>("userName");

  String get expiryDateTime => get<String>("expiryDateTime");

  set question(String question) => set<String>("question", question);

  set coverImage(String coverImage) => set<String>("coverImage", coverImage);

  set optionsType(String optionsType) =>
      set<String>("optionsType", optionsType);

  set totalNumberOfVotes(int totalNumberOfVotes) =>
      set<int>("totalNumberOfVotes", totalNumberOfVotes);

  set numberOfLikes(int numberOfLikes) =>
      set<int>("numberOfLikes", numberOfLikes);

  ///Name of user
  set userName(String userName) => set<String>("userName", userName);

  set expiryDateTime(String expiryDateTime) =>
      set<String>("expiryDateTime", expiryDateTime);

  set options(List<dynamic> options) => set<List<dynamic>>("options", options);

  set tags(List<dynamic> tags) => set<List<dynamic>>("tags", tags);

  set votes(Map<String, dynamic> votes) =>
      set<Map<String, dynamic>>("votes", votes);
}

Then I tried to type cast

 OfficialPoll officialPoll = officialPollLike.parent as OfficialPoll;

Which fails as it is not a subtype of ParseObject

Is there any way to convert it to OfficialPoll type even using some of the existing SDK code?

[GursheeshSingh]

Found the way to convert the ParseObject in PollLike to Official Type

print(officialPollLike.parent.runtimeType);
var officialPoll = jsonDecode(officialPollLike.parent.toString());
print(officialPoll.runtimeType);
OfficialPoll poll = OfficialPoll();
poll = poll.clone(officialPoll);
print(poll.question);

Output of the above code-

ParseObject
flutter: _InternalLinkedHashMap<String, dynamic>
flutter: Who is the best player? 2

Poll poll = Poll("OfficialPolls", PollType.OFFICIAL);

instead of

OfficialPoll poll = OfficialPoll();

also works

So I used the clone function which needs a map
As the parent object is of ParseObject type, I cannot use it to clone
Therefore, I use the toString() and jsonDecode function to convert it to a map
and then was able to convert it to OfficialPoll Type successfully