Extract data from an array in MongoDB by organizing it into sections based on dates

Question

Extract data from an array in MongoDB by organizing it into sections based on dates

As a beginner in the world of MongoDB, I'm trying to figure out how to extract data from an array in separate sections.

{
   "name":"User name",
   "messages":[
      {
         "message":"Message 1",
         "date":"2022-05-12T00:00:00.000Z"
      },
      {
         "message":"Message 2",
         "date":"2022-05-12T00:00:00.000Z"
      },
      {
         "message":"Message 3",
         "date":"2022-05-13T00:00:00.000Z"
      },
      {
         "message":"Message 4",
         "date":"2022-05-13T00:00:00.000Z"
      },
      {
         "message":"Message 5",
         "date":"2022-05-13T00:00:00.000Z"
      }
   ]
}

The desired outcome that I'm aiming for is

[
   {
      "date":"2022-05-12T00:00:00.000Z",
      "messages":[
         {
            "message":"Message 1",
            "date":"2022-05-12T00:00:00.000Z"
         },
         {
            "message":"Message 2",
            "date":"2022-05-12T00:00:00.000Z"
         }
      ]
   },
   {
      "date":"2022-05-13T00:00:00.000Z",
      "messages":[
         {
            "message":"Message 3",
            "date":"2022-05-13T00:00:00.000Z"
         },
         {
            "message":"Message 4",
            "date":"2022-05-13T00:00:00.000Z"
         },
         {
            "message":"Message 5",
            "date":"2022-05-13T00:00:00.000Z"
         }
      ]
   }
]

I haven't had much exposure to MongoDB aggregation yet and while I've searched through numerous queries on stack overflow, none have provided me with the assistance I need.

Is there a way to achieve this? If so, I would greatly appreciate any guidance. :)

javascript arrays mongodb aggregation-framework aggregation

Answer 1

Answer №1

To achieve the desired result, consider using aggregation in your query.

db.collection.aggregate([
  {
    $unwind: "$entries"
  },
  {
    $group: {
      _id: "$entries.timestamp",
      entries: {
        $push: "$entries"
      }
    }
  },
  {
    $project: {
      _id: 0,
      timestamp: "$_id",
      entries: 1
    }
  }
])

Answer 2

To achieve the desired result, consider using aggregation in your query.

db.collection.aggregate([
  {
    $unwind: "$entries"
  },
  {
    $group: {
      _id: "$entries.timestamp",
      entries: {
        $push: "$entries"
      }
    }
  },
  {
    $project: {
      _id: 0,
      timestamp: "$_id",
      entries: 1
    }
  }
])

Answer 3

Answer №2

$unwind - Breaking down the messages array into multiple documents.
$group - Grouping by messages.date and including the messages document in the messages array.
$project - Customizing the output documents.

db.collection.aggregate([
  {
    $unwind: "$messages"
  },
  {
    $group: {
      _id: "$messages.date",
      messages: {
        $push: "$messages"
      }
    }
  },
  {
    $project: {
      _id: 0,
      date: "$_id",
      messages: 1
    }
  }
])

Try out the Sample Mongo Playground

Answer 4

$unwind - Breaking down the messages array into multiple documents.
$group - Grouping by messages.date and including the messages document in the messages array.
$project - Customizing the output documents.

db.collection.aggregate([
  {
    $unwind: "$messages"
  },
  {
    $group: {
      _id: "$messages.date",
      messages: {
        $push: "$messages"
      }
    }
  },
  {
    $project: {
      _id: 0,
      date: "$_id",
      messages: 1
    }
  }
])

Try out the Sample Mongo Playground

Extract data from an array in MongoDB by organizing it into sections based on dates

Answer №1

Answer №2

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