Iterate through array of objects and obtain a new array of object

Question

I have below array of objects with each object having a projects attribute which further has its array of objects.

const data = [
    {
        "title": "Release",
        "projects": [
            {
                "name": "Server",
                "result": {
                    "success": 0,
                    "failure": 100
                },
            }
        ]
    },
    {
        "title": "Payments",
        "projects": [
            {
                "name": "Platform1",
                "result": {
                    "success": 100,
                    "failure": 0
                }
            },
            {
                "name": "Platform2",
                "result": {
                    "success": 50,
                    "failure": 50,
                }
            }
        ]
    }
]

I wanted to iterate through it and get the result as follows. name is nothing but concatenation of title and name from above data.


const result = [
    {
      name: 'Release-Server',
      success: 0,
      failure: 100,
    },
    {
      name: 'Payments-Platform1',
      success: 100,
      failure: 0,
    },
    {
      name: 'Payments-Platform2',
      success: 50,
      failure: 5,
    },
];

I have tried below ways but not able to figure out how to get exactly the result as shown above. can someone pls help on this.

data.forEach(prj => {
        prj.projects.forEach((project) => {
          // unable to get how to push these details into a new array of object
        })
      });

@CanPoyrazoğlu i know map will allow to create a new array of object but havent used flatMap. Do you have an example i can refer to ? — Aren Trot
– Aren Trot, Commented Nov 9, 2021 at 7:34
it was just an idea. The "practical example" section on the following link may help: davidtang.io/… — Can Poyrazoğlu
– Can Poyrazoğlu, Commented Nov 9, 2021 at 7:38
flatMap() is just a combination of flat() and map(), just like the name suggests — StackByMe
– StackByMe, Commented Nov 9, 2021 at 7:38

callback · Accepted Answer · 2021-11-09 07:37:42Z

6

You can do the following (Make sure you add checks for null/undefined references)

const data = [{
    "title": "Release",
    "projects": [{
      "name": "Server",
      "result": {
        "success": 0,
        "failure": 100
      },
    }]
  },
  {
    "title": "Payments",
    "projects": [{
        "name": "Platform1",
        "result": {
          "success": 100,
          "failure": 0
        }
      },
      {
        "name": "Platform2",
        "result": {
          "success": 50,
          "failure": 50,
        }
      }
    ]
  }
];

const result = data.flatMap(item =>
  item.projects.map(project => ({
    name: `${item.title}-${project.name}`,
    success: project.result.success,
    failure: project.result.failure
  })));

console.log(result);

answered Nov 9, 2021 at 7:37

callback

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1 Comment

StackByMe Over a year ago

As a sidenote (nothing is wrong). Instead of defining success and failure explicitly you can also just spread out project.result. This is usefull when at a later stage you want to add a property to the result object. This way you don't have to change the loop to also include that new property

Balastrong · Accepted Answer · 2021-11-09 07:39:17Z

You should use flatMap first because you have will change the number of elements (you start with 2, you end with 3) and inside a simple map to convert 1:1 each project into your final object.

Working Demo

const data = [{
    "title": "Release",
    "projects": [{
      "name": "Server",
      "result": {
        "success": 0,
        "failure": 100
      },
    }]
  },
  {
    "title": "Payments",
    "projects": [{
        "name": "Platform1",
        "result": {
          "success": 100,
          "failure": 0
        }
      },
      {
        "name": "Platform2",
        "result": {
          "success": 50,
          "failure": 50,
        }
      }
    ]
  }
];

var groupedData = data.flatMap((el) =>
  el.projects.map((proj) => ({
    name: el.title + "-" + proj.name,
    success: proj.result.success,
    failure: proj.result.failure,
  }))
);

console.log(groupedData);

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