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Execute built in function via mongo Shell

Hi ,

I need help or suggestion around running a built in function from mongoshell. Earlier mongo version has db.eval which provides function output but its deprecated now and couldnt use in my recent version of the mongshell.

2nd question , My aggregate logic is below, can I store this as system saved function if so how. I want to later access this using function. function lookup(key1,key2,key3,key4)

Example :

db.collection_new.aggregate([
{
 $lookup :{
  from: 'collection_ref',
  let :{key1 :"$key1",
        key2:"$key2",
        key3:"$key3",
        key4:"$key4"
        },
 pipeline:[
  {$match:{
		$expr:{
			$and : [{$eq :["$key1","$$key1"]},
					{$eq :["$key2","$$key2"]},
					{$eq :["$key3","$$key3"]},
					{$eq :["$key4","$$key4"]}
					]
      }
    }
  }],
  as : "result"
}}})

Hi,

Although not a 1-1 replacement, you might want to check if views can satisfy your requirements.

Best regards,
Kevin