$anyElementTrue operator in MongoDB

Its returns true or false $anyElementTrue accepts only one argument expression and returns true if evaluate expression true otherwise false.

Syntax:

{ $anyElementTrue: [ <expression> ] }

Example: Consider an survey collection with the following documents:

{ "_id" : 1, "responses" : [ true ] } { "_id" : 2, "responses" : [ true, false ] } { "_id" : 3, "responses" : [ ] } { "_id" : 4, "responses" : [ 1, true, "seven" ] } { "_id" : 5, "responses" : [ 0 ] } { "_id" : 6, "responses" : [ [ ] ] } { "_id" : 7, "responses" : [ [ 0 ] ] } { "_id" : 8, "responses" : [ [ false ] ] } { "_id" : 9, "responses" : [ null ] } { "_id" : 10, "responses" : [ undefined ] }

Run Following Query

db.survey.aggregate(    [      { $project: { responses: 1, isAnyTrue: { $anyElementTrue: [ "$responses" ] }, _id: 0 } }    ] )

Result:

{ "responses" : [ true ], "isAnyTrue" : true } { "responses" : [ true, false ], "isAnyTrue" : true } { "responses" : [ ], "isAnyTrue" : false } { "responses" : [ 1, true, "seven" ], "isAnyTrue" : true } { "responses" : [ 0 ], "isAnyTrue" : false } { "responses" : [ [ ] ], "isAnyTrue" : true } { "responses" : [ [ 0 ] ], "isAnyTrue" : true } { "responses" : [ [ false ] ], "isAnyTrue" : true } { "responses" : [ null ], "isAnyTrue" : false } { "responses" : [ null ], "isAnyTrue" : false }