CODEWITHSUNDEEP
arraysmongodbaggregation-framework
aroha_blue
aroha_blue

Reputation: 33

How to search an array for values present in another array and output the indexes of values found into a new array in [mongodb]

I have a Collection in each document is an array field and I want to search it for the occurrence of elements that are in another array and output the indexes of elements that are found as an array.

For example:

I have a document with foo field,

{
        foo = [1,4,3,6,6],
        foo = [1,5,7,5,8],
        foo = [2,4,3,1,6],
        foo = [1,4,9,6,7]
}

and an array which contains the elements to be searched

bar = [3,6]

I want the output to be 

{output = [2,3]}
{output = [-1,-1]}
{output = [2,4]}
{output = [-1,3]}

I have tried using aggregation pipeline and map function with $indexOfArray but can't seem to make it work.

Upvotes: 2

Views: 166

Answers (1)

s7vr
s7vr

Reputation: 75914

You can use $map expression.

db.collection.aggregate([
  {"$project":{
      "output":{
        "$map":{
         "input":[3,6],
         "in":{"$indexOfArray":["$foo","$$this"]}
        }
      }
   }}
])

Upvotes: 1

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