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  1. Documentation
  2. DOCS-563 documentation for valueOf() and toString()
  3. DOCS-584

Release notes for 2.2 should mention breaking change: ObjectId().valueOf() and ObjectId().toString() have reversed meanings

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    • Type: Icon: Sub-task Sub-task
    • Resolution: Done
    • Priority: Icon: Minor - P4 Minor - P4
    • Server_Docs_20231030
    • Affects Version/s: None
    • Component/s: Server
    • Labels:
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      We changed the result returned by the valueOf() and toString() methods of ObjectId() in 2.1.0 and later compared to the 2.0 series.

      Version 2.0
      MongoDB shell version: 2.0.8-rc0-pre-
connecting to: test
> var o = new ObjectId()
> o
ObjectId("507172c510b40cc18add2475")
> o.str
507172c510b40cc18add2475
> o.valueOf()
ObjectId("507172c510b40cc18add2475")
> o.toString()
507172c510b40cc18add2475
> o.tojson()
ObjectId("507172c510b40cc18add2475")
> typeof o
object
> typeof o.str
string
> typeof o.valueOf()
object
> typeof o.toString()
string
> typeof o.tojson()
string
> o.valueOf
function valueOf() {
    [native code]
}
> o.toString
function toString() {
    [native code]
}
> o.tojson
function () {
    return "ObjectId(\"" + this.str + "\")";
}
>
      Version 2.1, 2.2 and higher
      MongoDB shell version: 2.3.0-pre-
connecting to: test
> var o = new ObjectId()
> o
ObjectId("5071731713a0d4c2ef2a2c02")
> o.str
5071731713a0d4c2ef2a2c02
> o.valueOf()
5071731713a0d4c2ef2a2c02
> o.toString()
ObjectId("5071731713a0d4c2ef2a2c02")
> o.tojson()
ObjectId("5071731713a0d4c2ef2a2c02")
> typeof o
object
> typeof o.str
string
> typeof o.valueOf()
string
> typeof o.toString()
string
> typeof o.tojson()
string
> o.valueOf
function () {
    return this.str;
}
> o.toString
function () {
    return "ObjectId(" + tojson(this.str) + ")";
}
> o.tojson
function () {
    return this.toString();
}
>

      The short version is that any code using ObjectId().toValue() or ObjectId().toString() will break when moving from version 2.0 to version 2.2.

      If compatibility between versions 2.0 and 2.2 is required, use ObjectId().str, which is a string property holding the hex string value in both versions, or use ObjectId().tojson(), which returns a string containing 'ObjectId("<hex string value>")' in both versions.

      Alternatively, if changing affected code is not feasible, it is possible to revert the methods in 2.2 to their 2.0 meanings by changing ObjectId.prototype:

      revertObjectIdMethods.js
      // Revert ObjectId().toString(), .valueOf() and .tojson() to their version 2.0 behaviors
//
ObjectId.prototype.toString = function(){
    return this.str;
}
ObjectId.prototype.valueOf = function(){
    return "ObjectId(" + tojson(this.str) + ")";
}
ObjectId.prototype.tojson = function(){
    return "ObjectId(" + tojson(this.str) + ")";
}
      Example of using revertObjectIdMethods.js
      MongoDB shell version: 2.3.0-pre-
connecting to: test
> var o = new ObjectId()
> o.valueOf()
5071ad1b4ed39323ce5d275f
> o.toString()
ObjectId("5071ad1b4ed39323ce5d275f")
> o.tojson()
ObjectId("5071ad1b4ed39323ce5d275f")
> load("revertObjectIdMethods.js")
> o.valueOf()
ObjectId("5071ad1b4ed39323ce5d275f")
> o.toString()
5071ad1b4ed39323ce5d275f
> o.tojson()
ObjectId("5071ad1b4ed39323ce5d275f")
>

      See linked tickets for more information.

            Assignee:
            kay.kim@mongodb.com Kay Kim (Inactive)
            Reporter:
            tad Tad Marshall
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              Created:
              Updated:
              Resolved:
              11 years, 29 weeks ago