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  1. Core Server
  2. SERVER-31871

$expr does not seem to work with fields in array

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    • Type: Icon: Bug Bug
    • Resolution: Works as Designed
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: 3.6.0-rc2
    • Component/s: Querying
    • Labels:
      None
    • ALL
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      use jira;

db.expr.insert({
	"_id":"test",
	"max"{
		"date": ISODate('2017-11-08T00:00:00Z')
	},
	"arr":[
		{'id':1, "date": ISODate('2017-11-01T00:00:00Z')},
		{'id':2, "date": ISODate('2017-11-03T00:00:00Z')},
		{'id':3, "date": ISODate('2017-11-05T00:00:00Z')},
		{'id':4, "date": ISODate('2017-11-07T00:00:00Z')},
		{'id':5, "date": ISODate('2017-11-08T00:00:00Z')},
	],
	'maxdate': ISODate('2017-11-08T00:00:00Z')
});

// Works
db.expr.aggregate([	{
	  "$match": {
	    "$expr":
	        {"$eq": ["$maxdate", "$max.date"]
	    }
	    }
	  }
]);

// Works
db.expr.aggregate([
	{
		'$project':{"md":{"$max":"$arr.date"}, "maxdate":1},
	},
	{
	  "$match": {
	    "$expr":
	        {"$eq": ["$maxdate", "$md"]
	    }
	    }
	  }
]);

// Does not work
db.expr.aggregate([	{
	  "$match": {
	    "$expr":
	        {"$eq": ["$maxdate", "$arr.date"]
	    }
	    }
	  }
]);

// Does not work either
db.expr.aggregate([
	{
		'$addFields':{"md":{"$max":"$arr.date"}, "maxdate":1},
	},
	{
	  "$match": {
	    "$expr":
	        {"$eq": ["$maxdate", "$md"]
	    }
	    }
	  }
]);
      Show
      use jira; db.expr.insert({ "_id" : "test" , "max" { "date" : ISODate( '2017-11-08T00:00:00Z' ) }, "arr" :[ { 'id' :1, "date" : ISODate( '2017-11-01T00:00:00Z' )}, { 'id' :2, "date" : ISODate( '2017-11-03T00:00:00Z' )}, { 'id' :3, "date" : ISODate( '2017-11-05T00:00:00Z' )}, { 'id' :4, "date" : ISODate( '2017-11-07T00:00:00Z' )}, { 'id' :5, "date" : ISODate( '2017-11-08T00:00:00Z' )}, ], 'maxdate' : ISODate( '2017-11-08T00:00:00Z' ) }); // Works db.expr.aggregate([ { "$match" : { "$expr" : { "$eq" : [ "$maxdate" , "$max.date" ] } } } ]); // Works db.expr.aggregate([ { '$project' :{ "md" :{ "$max" : "$arr.date" }, "maxdate" :1}, }, { "$match" : { "$expr" : { "$eq" : [ "$maxdate" , "$md" ] } } } ]); // Does not work db.expr.aggregate([ { "$match" : { "$expr" : { "$eq" : [ "$maxdate" , "$arr.date" ] } } } ]); // Does not work either db.expr.aggregate([ { '$addFields' :{ "md" :{ "$max" : "$arr.date" }, "maxdate" :1}, }, { "$match" : { "$expr" : { "$eq" : [ "$maxdate" , "$md" ] } } } ]);

      Trying to match a field with another one in an array does not seem to be working.

      Also, using $expr to compare a projected field work, but not a new field created with $addFields

      Step to reproduce demonstrate the issue.

      I'm filling this as a major bug because this looks like important issues in the $expr mechanism to me.

            Assignee:
            james.wahlin@mongodb.com James Wahlin
            Reporter:
            hmducoulombier@marketing1by1.com Henri-Maxime Ducoulombier
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              Created:
              Updated:
              Resolved: