Find values in nested array using lodash

Question

I am trying to retrieve values back in a nested array but my function is returning back everything. I would like to just back the 'carTime' values in my array.

What my array is returning.

[
  {
    "carId": "13122",
    "carInstances": [
      {
        "carInstanceId": "472",
        "carTime": "2020-09-23T21:45:00.000+0000",
        "state": "COMPLETE",
      }
    ],
    "isPaused": false,
  },
  {
    "carId": "1312",
    "carInstances": [
      {
        "carInstanceId": "47209",
        "carTime": "2020-09-23T21:45:00.000+0000",
        "state": "COMPLETE",
      }
    ],
    "isPaused": false,
  },
]

Lodash:

const result = [
  {
    "carId": "13122656",
    "carInstances": [
      {
        "carInstanceId": "47209",
        "carTime": "2020-09-23T21:45:00.000+0000",
        "state": "COMPLETE",
      }
    ],
    "isPaused": false,
  },
  {
    "carId": "1312",
    "carInstances": [
      {
        "carInstanceId": "4720",
        "carTime": "2020-09-23T21:45:00.000+0000",
        "state": "COMPLETE",
      }
    ],
    "isPaused": false,
  },
]

const findCategoryById = (sections) => {
        const jobInstance = _.forEach(sections, (section) => {
          return section.carInstances.carTime;
        });
        return jobInstance;
      };
      findCategoryById(result)

Desired Output:

2020-09-23T21:45:00.000+0000,
2020-09-23T21:45:00.000+0000

Jonathan Hamel · Accepted Answer · 2021-03-19 21:40:37Z

1

You do not need lodash for solving this problem. A small JS function will do with the use of reduce and map. With lodash you could do: _(result).flatMap('carInstances').flatMap("carTime")).values()

const result = [
  {
    "carId": "13122656-169f-45fa-be47-26c9d23dcb7b",
    "carInstances": [
      {
        "carInstanceId": "47209558-f9e1-4f81-a600-5da6ce238a6e",
        "carTime": "2020-09-23T21:45:00.000+0000",
        "state": "COMPLETE",
      }
    ],
    "isPaused": false,
  },
  {
    "carId": "13122656-169f-45fa-be47-26c9d23dcb7b",
    "carInstances": [
      {
        "carInstanceId": "47209558-f9e1-4f81-a600-5da6ce238a6e",
        "carTime": "2020-09-23T21:45:00.000+0000",
        "state": "COMPLETE",
      }
    ],
    "isPaused": false,
  },
];

const listCarTime = (res) => {
  return res.reduce((acc, car) => {
    acc.push(...car.carInstances.map((instance) => instance.carTime));
    return acc;  
  }, []);
}

console.log("lodash", _(result).flatMap('carInstances').flatMap("carTime").values())


console.log("vanilla", listCarTime(result));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>

edited Mar 19, 2021 at 21:40

answered Mar 19, 2021 at 21:33

Jonathan Hamel

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1 Comment

Stephen P Over a year ago

It would be helpful to explain to OP "I would like to just back the 'carTime'" is done via the .map(i => i.carTime) part of your answer.

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