Pivot rows to columns in MongoDB

Question

The relevant question is Efficiently convert rows to columns in sql server. But the answer is specific to SQL.

I want the same result i.e. pivot row to column withou

Answer 1

Now, you can utilise new aggregation operator $arrayToObject to pivot MongoDB keys. This operator is available in MongoDB v3.4.4+

For example, given an example data of:

db.foo.insert({ provider: "Facebook", timestamp: '1371798000000', name: 'page_storytellers', value: 20871})
db.foo.insert({ provider: "Facebook", timestamp: '1371798000000', name: 'page_fans', value: 1291509})
db.foo.insert({ provider: "Facebook", timestamp: '1371798000000', name: 'page_fan_adds', value: 2829})
db.foo.insert({ provider: "Google", timestamp: '1371798000000', name: 'page_fan_adds', value: 1000})

You can utilise Aggregation Pipeline below:

db.foo.aggregate([
  {$group:
     {_id:{provider:"$provider", timestamp:"$timestamp"}, 
      items:{$addToSet:{name:"$name",value:"$value"}}}
  }, 
  {$project:
     {tmp:{$arrayToObject: 
       {$zip:{inputs:["$items.name", "$items.value"]}}}}
  }, 
  {$addFields:
     {"tmp.provider":"$_id.provider", 
      "tmp.timestamp":"$_id.timestamp"}
  }, 
  {$replaceRoot:{newRoot:"$tmp"}
  }
]);

The output would be:

{
  "page_fan_adds": 1000,
  "provider": "Google",
  "timestamp": "1371798000000"
},
{
  "page_fan_adds": 2829,
  "page_fans": 1291509,
  "page_storytellers": 20871,
  "provider": "Facebook",
  "timestamp": "1371798000000"
}

See also $group, $project, $addFields, $zip, and $replaceRoot

Answer 2

I have done something like this using aggregation. Could this help ?

db.foo.insert({ timestamp: '1371798000000', propName: 'page_fans', propValue: 100})
db.foo.insert({ timestamp: '1371798000000', propName: 'page_posts', propValue: 25})
db.foo.insert({ timestamp: '1371798000000', propName: 'page_stories', propValue: 50})

db.foo.aggregate({ $group: { _id: '$timestamp', result: { $push: { 'propName': '$propName', 'propValue': '$propValue' } }}})

{
    "result" : [
        {
            "_id" : "1371798000000",
            "result" : [
                {
                    "propName" : "page_fans",
                    "propValue" : 100
                },
                {
                    "propName" : "page_posts",
                    "propValue" : 50
                },
                {
                    "propName" : "page_stories",
                    "propValue" : 25
                }
            ]
        }
    ],
    "ok" : 1
}

You may want to use $sum operator along the way. See here