CODEWITHSUNDEEP
mongodbsorting
manojpt
manojpt

Reputation: 1269

MongoDB update with sort

Sample document looks like this: 

{
    _id: 1,
    "somearray": 
      [
        {
            year: 2013
        },
        {
            year: 2012
        },
        {
            year: 2011
        },
        {
            year: 2010
        }
      ]
}

The array "somearray" is sorted. Suppose if I update the second object {year : 2012} to {year : 2014}, is it possible to sort the array. the expected output after update is below:

{
    _id: 1,
    "somearray":
      [
        {
            year: 2014
        },
        {
            year: 2013
        },
        {
            year: 2011
        },
        {
            year: 2010
        }
     ]
}

Could any one help.

Upvotes: 3

Views: 8018

Answers (2)

magiccrafter
magiccrafter

Reputation: 5474

It is worth checking the mongo's $sort modifier. Introduces since version 2.4.

Here is the link to the reference: https://docs.mongodb.com/manual/reference/operator/update/sort/

The following example will just trigger the sort

db.collection.update(
   { _id: 1 },
   {
     $push: {
       somearray: {
         $each: [],
         $sort: { year: -1 }
       }
     }
   }
)

Upvotes: 1

Neo-coder
Neo-coder

Reputation: 7840

MongoDB allow to updated nested documents using $elemMatch and using $ operator so you can update year as below :

db.collectionName.update({"somearray":{"$elemMatch":{"year":2012}}},{"$set":{"somearray.$.year":2014}})

This query updated the year 2012 to 2015 but array positioned not changed.But if you want still to changed array positioned with updated values then you should used some programming logic or code I write this script which will update array and pushed with sorted 

function compare(a, b) {
  if(a.year > b.year) return -1;
  if(a.year < b.year) return 1;
  return 0;
}
var givenYear = 2012; // which year you want to update
var array = []; // empty array to push data 
db.collectionName.find().forEach(function(data) {
  var objects = data.somearray;
  for(var i = 0; i < objects.length; i++) {
    if(data.somearray[i].year == givenYear) {
      array.push({
        "year": 2014
      });
    } else {
      array.push({
        "year": data.somearray[i].year
      });
    }
  }
  var sortedArray = array.sort(compare); // pass to compare function to sort the array with year
  db.collectionName.update({
    "_id": 1,"somearray":{"$elemMatch":{"year":2012}} //match criteria
  }, {
    "$set": {
      "somearray": sortedArray // updated whole array with new sorted array
    }
  });
})

Note : compare function ref

Upvotes: 0

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