join

join(Array<L>, Array<R>, (leftValue: L) -> String, (rightValue: R) -> String): Array<Pair<L, R>>

Joins two arrays of objects by a given ID criteria.

join returns an array all the left items, merged by ID with any right items that exist.

Introduced in DataWeave 2.2.0. Supported by Mule 4.2 and later.

Parameters

Name Description

Name	Description
`left`	The left-side array of objects.
`right`	The right-side array of objects.
`leftCriteria`	The criteria used to extract the ID for the left collection.
`rightCriteria`	The criteria used to extract the ID for the right collection.

left

The left-side array of objects.

right

The right-side array of objects.

leftCriteria

The criteria used to extract the ID for the left collection.

rightCriteria

The criteria used to extract the ID for the right collection.

Example

This example shows how join behaves. Notice that the output only includes objects where the values of the input user.id and product.ownerId match. The function includes the "l" and "r" keys in the output.

Source

 %dw 2.0
 import * from dw::core::Arrays
 var users = [{id: "1", name:"Mariano"},{id: "2", name:"Leandro"},{id: "3", name:"Julian"},{id: "5", name:"Julian"}]
 var products = [{ownerId: "1", name:"DataWeave"},{ownerId: "1", name:"BAT"}, {ownerId: "3", name:"DataSense"}, {ownerId: "4", name:"SmartConnectors"}]
 output application/json
 ---
 join(users, products, (user) -> user.id, (product) -> product.ownerId)

Output

[
  {
    "l": {
      "id": "1",
      "name": "Mariano"
    },
    "r": {
      "ownerId": "1",
      "name": "DataWeave"
    }
  },
  {
    "l": {
      "id": "1",
      "name": "Mariano"
    },
    "r": {
      "ownerId": "1",
      "name": "BAT"
    }
  },
  {
    "l": {
      "id": "3",
      "name": "Julian"
    },
    "r": {
      "ownerId": "3",
      "name": "DataSense"
    }
  }
]