How to insert objects to Atlas using Relationships with Realm in Kotlin?

MongoDB Atlas App Services & Realm
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1

I have created to RealmObjects: Category and Product, and I have created a one-to-many relationship, where one category has multiple products.
When I insert a product to Atlas database the category is not showing up. The products are not showing up either in Category collection.

These are my Realm Objects:

class Product: RealmObject {
    @PrimaryKey
    var _id: ObjectId = ObjectId.create()
    var name: String? = null
    var quantity: Int? = null
    var price: Float? = null
    var image: String? = null
    var shortDescritpion: String? = null
    var longDescritpion: String? = null
    var barcode: Long? = null
    var category: Category? = null
}

class Category: RealmObject {
    @PrimaryKey
    var _id: ObjectId = ObjectId.create()
    var name: String = ""
    var image: String = ""
    var products: RealmList<Product> = realmListOf<Product>()
    var company_id: Company? = null
}

These is product schema:

{
  "title": "Product",
  "bsonType": "object",
  "required": [
    "_id",
    "_partition"
  ],
  "properties": {
    "_id": {
      "bsonType": "objectId"
    },
    "_partition": {
      "bsonType": "string"
    },
    "name": {
      "bsonType": "string"
    },
    "quantity": {
      "bsonType": "long"
    },
    "price": {
      "bsonType": "float"
    },
    "image": {
      "bsonType": "string"
    },
    "shortDescritpion": {
      "bsonType": "string"
    },
    "longDescritpion": {
      "bsonType": "string"
    },
    "barcode": {
      "bsonType": "long"
    },
    "category": {
      "bsonType": "objectId"
    }
  }
}

This is category schema:

Relationship:

{
  "company_id": {
    "ref": "#/relationship/mongodb-atlas/bestock-database/Company",
    "foreignKey": "_id",
    "isList": false
  },
  "products": {
    "ref": "#/relationship/mongodb-atlas/bestock-database/Product",
    "foreignKey": "_id",
    "isList": true
  }
}

Body:

{
  "title": "Category",
  "bsonType": "object",
  "required": [
    "_id",
    "_partition",
    "name",
    "image"
  ],
  "properties": {
    "_id": {
      "bsonType": "objectId"
    },
    "_partition": {
      "bsonType": "string"
    },
    "name": {
      "bsonType": "string"
    },
    "image": {
      "bsonType": "string"
    },
    "products": {
      "bsonType": "array",
      "items": {
        "bsonType": "objectId"
      }
    },
    "company_id": {
      "bsonType": "objectId"
    }
  }
}

The database looks like this after I insert a category and a product:

Screenshot 2022-08-22 at 11.39.11 AM
Screenshot 2022-08-22 at 11.39.11 AM1796×371 22.3 KB

Screenshot 2022-08-22 at 11.39.30 AM
Screenshot 2022-08-22 at 11.39.30 AM1693×465 41.6 KB

2

Hi @Besart_H ,

It’s not clear from the information you provide, but, are you using Partition-based Sync, or Flexible Sync?

If the first is the case, the 2 records you report will never end up in the same partition, as they have different partition values, so the relationship won’t work.

If you’re using Flexible Sync instead, then the _partition field is redundant, of course

3

Hi @Paolo_Manna I am using partition-based Sync

4

Then, as explained before, the relationship can’t possibly work, as the Product document is in the product partition, while the Category is in the category partition, and relationships don’t work cross-partition.

To have it working, both objects should be in the same partition.

You may want to re-evaluate your data structure accordingly: some docs about different Sync modes, and Partition-based Sync may help here.

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