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Javascript – How can I filter an array, using a nested value?

I got an array with objects

"times": [{
  "id" : "id",
    "name" : "place",
    "location" : "place",
    "hours" : [
    {"day": "Sunday", "day_id": 0,
  "tags": "" },
    {"day": "Monday", "day_id": 1,
"tags": "" },
    {"day": "Tuesday", "day_id": 2,
"tags": "" },
    {"day": "Wednesday", "day_id": 3,
"tags": "" },
    {"day": "Thursday", "day_id": 4,
"tags": "" },
    {"day": "Friday", "day_id": 5,
"tags": "" },
    {"day": "Saturday", "day_id": 6,
"tags": "" }
    ]
    }
    ]

I am trying to filter into the Hours array within the object.

I am trying to find the objects that contains a specific day_id within the hours array.

I tried

let f1 = times.filter((item: { id: string; hours: { day_id : number;};}) => item.hours.day_id == 0 );

That did not work. What am I doing wrong here ?

Tags:

3

Answers


  1. 0

    If you wrap the above code in a JSON object like this:

    const arr = {
  "times": [
    {
      "id": "id",
      "name": "place",
      "location": "place",
      "hours": [
        { "day": "Sunday", "day_id": 0, "tags": "" },
        { "day": "Monday", "day_id": 1, "tags": "" },
        { "day": "Tuesday", "day_id": 2, "tags": "" },
        { "day": "Wednesday", "day_id": 3, "tags": "" },
        { "day": "Thursday", "day_id": 4, "tags": "" },
        { "day": "Friday", "day_id": 5, "tags": "" },
        { "day": "Saturday", "day_id": 6, "tags": "" }
      ]
    }
  ]
};

    You can write a function to filter the hours sub-array by day_id as such:

    function filterHoursByDayId(arr, dayId) {
  return arr.times.map(item => ({
    ...item,
    hours: item.hours.filter(hour => hour.day_id === dayId)
  }));
}

    Note that this only really extracts an entry from the hours sub-array and leaves everything else untouched. If you want to filter objects in the times array, you can use the following:

    function filterTimesByDayId(arr, dayId) {
  return arr.times.filter(item => item.hours.some(hour => hour.day_id === dayId));
}
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  2. 0

    I can’t understand your question. But I think that you are trying to filter the times array which you will get from a json, so let’s put it in a variable

    let data = your json (times) here`

    Now we have it in a variable, but the times is an array and you want to filter the hours array inside each item of that array, so this will be a nested filter:

    data.times.filter(({hours}) => {
 return hours
  .filter(({day_id}) => day_id ===0)
})
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  3. 0

    The issue with your current approach is that hours is an array, so you need to iterate over each item in the hours array to check the day_id. Additionally, since hours is an array of objects, you cannot directly access day_id on item.hours. You need to iterate over each hour object and then check its day_id.

    let filteredHours = times.filter((item) => {
// Check if any hour object in the hours array has the desired day_id
return item.hours.some((hour) => hour.day_id === 0);

    });

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