Related Object Properties from one-to-many relation

Android
1

Hi,

I am following the Social App blog post (https://backendless.com/how-to-build-social-app-backend-backendless-1/)

From the post.likes relation column (which is a one-to-many to users table) we want to load only the users.objectId property

This is my query on the Posts table (notice the “likes.objectId as likedBy” property)

val queryBuilder = DataQueryBuilder.create()
        queryBuilder.whereClause =  "ownerId= '$userId' OR ownerId in (Users[objectId='$userId'].following.objectId)"
        queryBuilder.addProperties("title", "content", "image", "location",
            "locationName", "created", "updated", "ownerId", "objectId",
            "postOwner.name as postUserName",
            "postOwner.imageUrl as postUserImage",
            "Count(likes) as totalLikesCount",
            "likes.objectId as likedBy"
            ).setGroupBy("objectId")
            .setSortBy("created desc")
            .setRelated("postOwner")
            .setRelated("likes")

but all likes/user properties are loaded

{
  "content": "My First Post",
  "created": "Oct 15, 2020 09:48:03",
  "image": "https://backendlessappcontent.com/...",
  "likes": [
    {
      "properties": {
        "lastName": "-",
        "lastLogin": "Oct 15, 2020 13:26:28",
        "userStatus": "ENABLED",
        "created": "Oct 11, 2020 08:01:50",
        "county": "HUNEDOARA",
        "ownerId": "88F9E311-9B24-4B47-9EDC-43AD6B1A7BB7",
        "socialAccount": "BACKENDLESS",
        "firstName": "-",
        "___class": "Users",
        "blUserLocale": "en",
       "updated": "Oct 11, 2020 08:07:17",
        "email": "costi@leadingedge.ro",
        "objectId": "88F9E311-9B24-4B47-9EDC-43AD6B1A7BB7"
      }
    }
  ],
  "location": {
    "x": 22.9072331,
    "y": 45.7678128,
    "srs": "WGS84"
  },
  "objectId": "A8A286BB-F389-4653-A7A8-EE2EF2FCE0FC",
  "ownerId": "917361FD-D6F7-4881-8250-1F59370BBEF1",
  "title": "First Post",
  "totalLikesCount": 3
}

We would however expect to see only the object id property, like this

{
  "content": "My First Post",
  "created": "Oct 15, 2020 09:48:03",
  "image": "https://backendlessappcontent.com/...",
  "likes": [
    {
      "properties": {
        "objectId": "88F9E311-9B24-4B47-9EDC-43AD6B1A7BB7",
      }
    }
  ],
  "location": {
    "x": 22.9072331,
    "y": 45.7678128,
    "srs": "WGS84"
  },
  "objectId": "A8A286BB-F389-4653-A7A8-EE2EF2FCE0FC",
  "ownerId": "917361FD-D6F7-4881-8250-1F59370BBEF1",
  "title": "First Post",
  "totalLikesCount": 1
}

Hope this makes sense and any help is much appreciated

Thanks
Constantin

2

Hi Constantin,

What happens to the result if you remove the following line from the queryBuilder composition:

.setRelated("likes")

?

Regards,
Mark

3

Hi Mark,
I removed it and no likes properties are returned in the result now

{
  "content": "Test Post",
  "created": "Oct 15, 2020 09:48:03",
  "image": "https://backendlessappcontent.com/",
  "liked": false,
  "location": {
    "x": 22.9072331,
    "y": 45.7678128,
    "srs": "WGS84"
  },
  "locationName": "",
  "loggedUserIsOwner": false,
  "objectId": "A8A286BB-F389-4653-A7A8-EE2EF2FCE0FC",
  "ownerId": "917361FD-D6F7-4881-8250-1F59370BBEF1",
  "postOwner": {
    "properties": {
      "lastName": "User",
      "lastLogin": "Oct 15, 2020 14:57:24",
      "gdprConsent": false,
      "userStatus": "ENABLED",
      "bikerSince": 2016,
      "created": "Sep 22, 2020 20:41:27",
      "county": "",
      "ownerId": "917361FD-D6F7-4881-8250-1F59370BBEF1",
      "socialAccount": "GOOGLE_PLUS",
      "firstName": "David",
      "public": true,
      "imageUrl": "https://backendlessappcontent.com/",
      "name": "David",
      "___class": "Users",
      "blUserLocale": "en",
      "id": "116714605064186866884",
      "updated": "Oct 15, 2020 07:24:58",
      "email": "",
      "objectId": "917361FD-D6F7-4881-8250-1F59370BBEF1"
    }
  },
  "postUserImage": "https://backendlessappcontent.com/...",
  "postUserName": "David",
  "title": "Test Post",
  "totalLikesCount": 5
}

Mark, the reason I need all the post likes.user ids is so I can loop through them to see if current logged user has liked the post

Thanks
C.

4

Hello @Constantin_Craciunescu

Have you seen the next part of this article https://backendless.com/how-to-build-a-social-app-backend-backendless-2/ ?

There is a part of how to implement this.

Regards, Vlad

5

to load all the users ids it’s not good idea because there might be a ton of users and it will be a slow request, much better just to check if the current user is exited in the relations

6

Hi Valdimir
Totally agree with being too slow to load all the user id’s

And yes, I did looked at the at the code in the second part but we use the Android SDK and we plan to give it a go with that a approach.

much better just to check if the current user is exited in the relations

I think the code in the blog article checks if the post objectId exists in curent user liked posts

Thanks,
C.

7

yes, you can find it in the async function loadPosts(currentUserId, whereClause) API method

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