Mongoose - How do i find in a collection from an array of object ids

Question

Lets say that I have an array on Object Ids:

[ 1, 2, 3, 4, 5 ]

and I have a collection called user which contains this value:

[
  {
     _id: 3,
     name: 'hehe'
  },

  {
     _id: 5,
     name: 'hehe1'
  },

  {
     _id: 2,
     name: 'hehe2'
  },

  {
     _id: 1,
     name: 'hehe3'
  },

  {
     _id: 4,
     name: 'hehe4'
  },

  {
     _id: 6,
     name: 'hehe5'
  }
]

How do i query the array object ids to the collection "user"? which the result should be the same order as the array of Object ids, would that be possible?

Thanks in advance!

stackoverflow.com/questions/22797768/…

Ashh
– Ashh

2020-01-21 04:56:48 +00:00
Commented Jan 21, 2020 at 4:56 — Ashh
– Ashh, Commented Jan 21, 2020 at 4:56

mickl · Accepted Answer · 2020-01-21 04:53:07Z

1

You can use $in to filter the documents and then you can use $indexOfArray to add special field which can be used as a key for $sort:

db.collection.aggregate([
    {
        $match: { _id: { $in: [ 1, 2, 3, 4, 5 ] } }
    },
    {
        $addFields: { idx: { $indexOfArray: [ [ 1, 2, 3, 4, 5 ], "$_id" ] } }
    },
    {
        $sort: { idx: 1 }
    }
])

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answered Jan 21, 2020 at 4:53

mickl

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Comments

Subburaj · Accepted Answer · 2020-01-21 04:29:59Z

0

To get the documents of Id array you can use $in as follows

collection.find( { key: { $in: [array] }}, callback );

NOTE:

Its not recommended to use order of documents to do some logic. We can't expect the order the same all time.

edited Jan 21, 2020 at 4:29

answered Jan 21, 2020 at 4:17

Subburaj

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