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Iterating nested object

This example shows how to flatten complex JavaScript object into rows and send required properties to the output.

Motivation

Suppose we have to process complex structure of users and their phones. However, subsequent connector is not able to process complex schema (e.g. SQL Connectors), so we have to transform complex data into particular rows.

Ouput schema

Column	Data type
Login	string
PhoneNumber	string

Statement

// create array with nested objects
let users = [                   
  {                       
    "ID": 1,            
    "Login": "Alice",
    "Phones": [
      { 
        "Type": "Mobile",
        "Number": "+420721234567" 
      },
      { 
        "Type": "Home",
        "Number": "+420722345678" 
      }
    ]
  },
  {                  
    "ID": 2,       
    "Login": "Bob",
    "Phones": [
      { 
        "Type": "Mobile",
        "Number": "+420723456789" 
      }
    ]
  }
];

// flat array for collecting result
let phones = [];

// outer iteration of users
users.forEach((user) => {

    // log outer record
    log.info(`Checking phones from ${user.Login}...`);

    // inner itearation of user''s numbers
    user.Phones.forEach((phone) => {

        // log user''s phone number and type
        log.info(`Found phone ${phone.Number} (${phone.Type})`);

        // add found number to the resulting array
        phones.push(
        { 
            "Login" : user.Login,
            "PhoneNumber" : phone.Number
        })
    });
});

return phones;

Result

Login	PhoneNumber
Alice	+420721234567
Alice	+420722345678
Bob	+420723456789