How can I change null values in aggregation using MongoDB

Question

I'm having a hard time to get this code working . I have an aggregation query in mongo db in which I do some operations inside . The query without the $ifNull operator is working fine , however I'm getting some null values that I do not want to be printing. I've read the documentation of $ifNull operators , but I am not able to get this code working. I have this code so far , witch is giving me this error :

SyntaxError: Unexpected token :

I think that's the ":" from the ifnull but I don't know why. I'm following the sintax that is on the documentation in the official website. I've also tried to use another project field in order to filter the Null values , but it didn't work. This is de query so far :

 db.cleandrivers.aggregate(
 [
 {
    $project :
      { _id:"$_id", 
        week : {$week : "$recruiter.date"},
        dif: {   
                $ifNull: [$divide : [{$subtract : ["$personal.stat.first_inspected","$recruiter.date"]}  , 1000 * 60 * 60 ], "0"]
             }
      }
 }, { $match : { week: 11  }  } 
 ])

Edit : Everything is working fine , this is a query that is actually working counting the recruited ppl giving an specific week.

  db.cleandrivers.aggregate(
    ...  [
    ...  {
    ...  $project :
    ...    { _id:"$_id", 
    ...      week : {$week : "$personal.stat.recruited"}
    ...    }
    ...  },
    ...  { $match : { $and: [ {week: 10}]  }  }, 
    ... {$group: { _id: "Sum",sum: {$sum : 1}}} ])

Output :

   { "_id" : "Sum", "sum" : 199 }

This is my document sintax :

 "personal" : {
                    "stat" : {
                            "recruited" : ISODate("2015-02-02T14:30:32.089Z"),
                            "first_inspected" : ISODate("2015-02-02T14:33:15.956Z"),
                            "targo" : ISODate("2015-02-06T17:51:00.672Z")
                    }

The problem is that when I use the same query that i used when i was trying to count the recruited ppl , its giving me an error ,because there are some documents that do not have that field. I am really confused on how do I have to filter all the documents that have the field first_inspected in their documents , and count them giving a week . The error happens on the $week line witch tries to convert a null date into a week and it gives me an error.

wdberkeley · Accepted Answer · 2015-03-31 18:15:25Z

6

I reformatted and patched the syntax error:

db.cleandrivers.aggregate([
    { "$project" : {
        "_id" : "$_id", 
        "week" : { "$week" : "$recruiter.date" },
        "dif" : {   
            "$ifNull" : [{ "$divide" : [{ "$subtract" : ["$personal.stat.first_inspected", "$recruiter.date"] }, 1000 * 60 * 60 ] }, "0"]
        }
    } },
    { "$match" : { "week" : 11 } } 
])

The problem was that you didn't have the $divide expression inside an object, so it was like

[ "$divide" : stuff, more, stuff]

instead of

[{ "$divide" : stuff }, more, stuff]

I can't help you with getting the aggregation to return what you want as I don't know exactly what you're looking for. If you need more help with that, could you edit the question to include a sample document and a description of what result you want to get from it?

answered Mar 31, 2015 at 18:15

wdberkeley

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2 Comments

Giuseppe Over a year ago

i edited my question adding some details of my actual mistake . I'm having problem with some documents that have null value on a date field and i cant aggregate them . (i am trying to exclude and count only the ones that exist in an especific field)

Giuseppe Over a year ago

I edited by mistake your answer, can you delete my edits so others can see your answer ?

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