how can I create an array based some fields in mongodb?

Question

eg: the input is

{
    "_id" : ObjectId("5e79ae1c11344b2895797042"),
    "startDay" : "20200312",
    "endDay" : "20200314"
}

I want to get ['20200312','20200313','20200314']. What should I do ?

Do the numbers increment by 1. Do you want to store the array as a field in the document — prasad_
– prasad_, Commented Mar 24, 2020 at 9:11

Mohammad Faisal · Accepted Answer · 2020-03-24 09:49:47Z

1

I have used $range which returns Array of numbers between range and $range accepts only integers. So, I convert the String values of startDay and endDay to integers using $toInt

Try this query,

db.collection.aggregate([
  {
    "$project": {
      "days": {
        "$range": [
          {
            "$toInt": "$startDay"
          },
          {
            "$add": [
              {
                "$toInt": "$endDay"
              },
              1
            ]
          }
        ]
      }
    }
  }
])

Query Result

[
  {
    "_id": ObjectId("5e79ae1c11344b2895797042"),
    "days": [
      20200312,
      20200313,
      20200314
    ]
  }
]

Query Test

answered Mar 24, 2020 at 9:49

Mohammad Faisal

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