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  1. Core Server
  2. SERVER-14670

Add expressions to determine the length of a string

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    • Fully Compatible
    • Query 12 (04/04/16)

      Syntax

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

      Examples

      Input

      {_id: 0, string: "cliché"}

      Pipeline

      db.coll.aggregate([{
    $project: {
        byteLength: {$strLenBytes: "$string"},
        cpLength: {$strLenCP: "$string"}
    }
}])

      Output

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

      Original Description

      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 }

        1. length-operator.diff
          2 kB

            Assignee:
            benjamin.murphy Benjamin Murphy
            Reporter:
            falsecz Lukas Benes
            Votes:
            15 Vote for this issue
            Watchers:
            19 Start watching this issue

              Created:
              Updated:
              Resolved: