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Update with Adding a Relation

The Deep Save API can be used to update an existing object and set a relation with a new child (or parent). Consider the examples below:

Existing Parent and New Child

This example retrieves an existing parent object (Order) and uses the Deep Save API to perform the following:

  1. Save new child object (OrderItem)
  2. Establish relationship between the Order and the new OrderItem.

The Order object already has two related OrderItem objects before the sample code below runs:



When working with relationships, the Deep Save API applies the "accumulation" policy. This means the following: if a parent object in the database already has some related objects and you update the object with new child objects in the relation, these objects will be added to the relation.

// get the order with the relations.
const order = await Backendless.Data.of('Order').findFirst()

// create new order item
const grapes = { name: 'Grapes', price: 3.99 }

const orderItems = []
// add grapes to the existing order items on the server

// put the list with grapes added to it back into order
order.orderItems = orderItems

// deep save the order

// get the order object.
const order = await Backendless.Data.of(Order).findFirst()

// create new order item
const grapes = new OrderItem({ name: 'Grapes', price: 3.99 })

// add new order item to the existing ones

// deep save the order
Order class:
class Order {
 constructor(data) {
   data = data || {}

   this.objectId = data.objectId
   this.customer = data.customer
   this.orderItems = data.orderItems || []

 addItem(item) {
OrderItem class:
class OrderItem {
 constructor(data) {
   data = data || {} =
   this.price = data.price

After the code runs, the new OrderItem object is saved in the database and the Order object relation is expanded to include it: