Question 116862 in Mongodb Question posted in
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MongoDB – Total number of objects in array vs field

I need to get total count of objects in the "photo" array field, and compare it to the value in "mls_media_count" field, so that I can detect when the values do not match.

    open_houses:null
    open_houses_lock:false
    photos:Array
         0:Object
         1:Object
         2:Object
         3:Object
         4:Object
         5:Object
         6:Object
         7:Object
         8:Object
         9:Object
     mls_media_count: 8

I have tried using $unwind, $project, $size, but haven’t had luck getting it to work.
Thanks in advance!

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2

Answers


  1. Chosen as BEST ANSWER
    0

    Thank you for response! This got me on right track and i ended up writing it like this:

        [{
 $match: {version: '5'
 }
}, {
 $project: {
  item: -1,
  Photos: {
   $cond: {
    'if': {
     $isArray: '$photos'
    },
    then: {
     $size: '$photos'
    },
    'else': 'NA'
   }
  },
  mls_number: 1,
  mls_media_count: 1,
  'system.kw_photo_count': 1
 }
}, {
 $match: {
  $expr: {
   $ne: [
    '$Photos',
    '$mls_media_count'
   ]
  }
 }
}, {
 $count: 'list_id'
}]

  2. 0

    Query

    • $size can give the size of the array, and we can compare it with the media_count
    • first query keeps the documents where size is not correct
    • second query keeps the documents where size is correct

    Playmongo

    aggregate(
[{"$match": 
   {"$expr": {"$ne": [{"$size": "$photos"}, "$mls_media_count"]}}}])

    Playmongo

    aggregate(
[{"$match": 
   {"$expr": {"$eq": [{"$size": "$photos"}, "$mls_media_count"]}}}])
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