Prerequisites
Steps to reproduce
When using Windows PowerShell 5.1, one can use the ConvertFrom-Json CmdLet to parse JSON strings.
Empty arrays are correctly parsed and return an object that can be piped into the ForEach-Object CmdLet and behaves accordingly.
However, from PowerShell Core 7.x, ConvertFrom-Json now returns a null value when parsing the string "[]".
The FAQ page does not help.
I have not been able to track if that is a desired change from Windows PowerShell 5.1.
I have tested this behavior with:
- PSCore 7.1.5 stable release.
- PSCore 7.2.1 stable release.
- PSCore 7.2.0-daily20211124.2 (daily build)
Expected behavior
PS> (ConvertFrom-JSON "[]").GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Object[] System.Array
Actual behavior
PS> (ConvertFrom-JSON "[]").GetType()
InvalidOperation: You cannot call a method on a null-valued expression.
Error details
PS> Get-Error
Exception :
Type : System.Management.Automation.RuntimeException
ErrorRecord :
Exception :
Type : System.Management.Automation.ParentContainsErrorRecordException
Message : You cannot call a method on a null-valued expression.
HResult : -2146233087
CategoryInfo : InvalidOperation: (:) [], ParentContainsErrorRecordException
FullyQualifiedErrorId : InvokeMethodOnNull
InvocationInfo :
ScriptLineNumber : 1
OffsetInLine : 1
HistoryId : -1
Line : (ConvertFrom-JSON "[]").GetType()
PositionMessage : At line:1 char:1
+ (ConvertFrom-JSON "[]").GetType()
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CommandOrigin : Internal
ScriptStackTrace : at <ScriptBlock>, <No file>: line 1
TargetSite : System.Object CallSite.Target(System.Runtime.CompilerServices.Closure, System.Runtime.CompilerServices.CallSite, System.Object)
Message : You cannot call a method on a null-valued expression.
Data : System.Collections.ListDictionaryInternal
Source : Anonymously Hosted DynamicMethods Assembly
HResult : -2146233087
StackTrace :
at CallSite.Target(Closure , CallSite , Object )
at System.Dynamic.UpdateDelegates.UpdateAndExecute1[T0,TRet](CallSite site, T0 arg0)
at System.Management.Automation.Interpreter.DynamicInstruction`2.Run(InterpretedFrame frame)
at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
CategoryInfo : InvalidOperation: (:) [], RuntimeException
FullyQualifiedErrorId : InvokeMethodOnNull
InvocationInfo :
ScriptLineNumber : 1
OffsetInLine : 1
HistoryId : -1
Line : (ConvertFrom-JSON "[]").GetType()
PositionMessage : At line:1 char:1
+ (ConvertFrom-JSON "[]").GetType()
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CommandOrigin : Internal
ScriptStackTrace : at <ScriptBlock>, <No file>: line 1Environment data
PS> $PSVersionTable
Name Value
---- -----
PSVersion 7.2.0-daily20211124.2
PSEdition Core
GitCommitId 7.2.0-daily20211124.2
OS Microsoft Windows 10.0.19042
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0Visuals
No response
Prerequisites
Steps to reproduce
When using Windows PowerShell 5.1, one can use the
ConvertFrom-JsonCmdLet to parse JSON strings.Empty arrays are correctly parsed and return an object that can be piped into the
ForEach-ObjectCmdLet and behaves accordingly.However, from PowerShell Core 7.x,
ConvertFrom-Jsonnow returns a null value when parsing the string"[]".The FAQ page does not help.
I have not been able to track if that is a desired change from Windows PowerShell 5.1.
I have tested this behavior with:
Expected behavior
Actual behavior
Error details
Environment data
Visuals
No response