Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-30417

add expression to get value by keyname from object

    XMLWordPrintableJSON

Details

    • Fully Compatible
    • Query 2020-08-10, Query 2020-08-24, Query Optimization 2021-04-05, Query Optimization 2021-04-19, Query Optimization 2021-05-03

    Description

      While it's possible via combined use of $objectToArray and $filter with $map, it would be nice to have a simple expression to get value of particular field of an object:

      db.foo.find()
      		 
      { _id: 1, a: 5, foo: { b: "a", c: 99.9 } }
      		 
      db.foo.aggregate({$project:{ foo_c_is: {$getField:[ "c", "$foo" ] } } })
      		 
      { _id: 1, foo_c_is: 99.9 }

      This will allow easily plucking out a value when the field name is stored in another part of the same document, or when it has some funny character that precludes it being used as subfield name (like leading "$") as in SERVER-30365 and SERVER-14466 or embedded '.' when querying oplog or system.profile collections.

      Second argument could be optional and default to "$$ROOT".

      Attachments

        Issue Links

          causes

          Task - A task that needs to be done. COMPASS-5173 Add expression to get value by keyname from object

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. MONGOSH-1003 Add expression to get value by keyname from object

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. VSCODE-299 Add expression to get value by keyname from object

          • Major - P3 - Major loss of function.
          • Closed
          is depended on by

          Bug - A problem which impairs or prevents the functions of the product. SERVER-21889 Oplog format for $set operations on subdocuments creates format that is not queryable

          • Minor - P4 - Minor loss of function, or other problem where easy workaround is present.
          • Backlog

          Task - A task that needs to be done. COMPASS-5126 Add expression to set value in object given field name expression

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. MONGOSH-1010 Add expression to set value in object given field name expression

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. VSCODE-300 Add expression to set value in object given field name expression

          • Major - P3 - Major loss of function.
          • Closed
          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. SERVER-38124 executing the expression in a field

          • Major - P3 - Major loss of function.
          • Closed

          New Feature - A new feature of the product, which has yet to be developed. SERVER-38463 Add $objectValueAt Expression

          • Minor - P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-37341 get value from document using expression

          • Major - P3 - Major loss of function.
          • Closed
          is related to

          Bug - A problem which impairs or prevents the functions of the product. SERVER-56546 Update $getField expression syntax

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-56224 Support $getField in SBE

          • Major - P3 - Major loss of function.
          • Backlog

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-30575 Please add escaping convention for dot and dollar signs!

          • Major - P3 - Major loss of function.
          • Backlog
          related to

          Bug - A problem which impairs or prevents the functions of the product. SERVER-14466 Support projecting the $id or $ref for a DBRef() field

          • Major - P3 - Major loss of function.
          • Closed

          New Feature - A new feature of the product, which has yet to be developed. PHPLIB-24 Implement DBRef model class

          • Major - P3 - Major loss of function.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-30365 How to exclude (sub)fields starting with $ in a query projection

          • Major - P3 - Major loss of function.
          • Backlog

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-41611 add expression to set value in object given field name expression

          • Major - P3 - Major loss of function.
          • Closed

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-57914 Make $getField return missing if "input" is missing or not an object

          • Major - P3 - Major loss of function.
          • Closed

          Activity

            People

              alya.berciu@mongodb.com Alya Berciu
              asya.kamsky@mongodb.com Asya Kamsky
              Votes:
              14 Vote for this issue
              Watchers:
              21 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: