[SERVER-14670] Add expressions to determine the length of a string - MongoDB Jira

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{$strLenBytes: <expression>}

{$strLenCP: <expression>}  // CP stands for UTF-8 'code points'.

{_id: 0, string: "cliché"}

db.coll.aggregate([{

    $project: {

        byteLength: {$strLenBytes: "$string"},

        cpLength: {$strLenCP: "$string"}

}])

{_id: 0, byteLength: 7, cpLength: 6}

We need to determine string length in aggregation pipeline

eg:

db.kol.insert({"text": "abcde"})

db.kol.insert({"text": "ab"})

db.kol.aggregate({ $project: { "text_length": {$length: "$text"  }}})

result:

{ "_id" : ObjectId("53d0c9bdc2644cdc0ab835f5"), "text_length" : 5 }

{ "_id" : ObjectId("53d0c9c1c2644cdc0ab835f6"), "text_length" : 2 }

is depended on by

CSHARP-1660 Add expressions to determine the length of a string

is documented by

DOCS-8709 Document $strLenBytes/$strLenCP

is duplicated by

SERVER-5319 provide strlen expression for $project

is related to

DRIVERS-297 Aggregation Framework Support for 3.4

Participants:: Asya Kamsky, Benjamin Murphy, Bradley Arsenault, Charlie Swanson, David Moravek, Githook User, hari.khalsa@10gen.com, Lukas Benes