ConvertFrom-Expression.md

ConvertFrom-Expression

Deserializes a PowerShell expression to an object.

Syntax

ConvertFrom-Expression
    -InputObject <String>
    [-LanguageMode <PSLanguageMode> = 'Restricted']
    [-ListAs <Object>]
    [-MapAs <Object>]
    [<CommonParameters>]

Description

The ConvertFrom-Expression cmdlet safely converts a PowerShell formatted expression to an object-graph existing of a mixture of nested arrays, hashtables and objects that contain a list of strings and values.

Parameters

-InputObject <String>

Specifies the PowerShell expressions to convert to objects. Enter a variable that contains the string, or type a command or expression that gets the string. You can also pipe a string to ConvertFrom-Expression.

The InputObject parameter is required, but its value can be an empty string. The InputObject value can't be $null or an empty string.

Type:	String
Mandatory:	True
Position:	Named
Default value:
Accept pipeline input:	False
Accept wildcard characters:	False

-LanguageMode <PSLanguageMode>

Defines which object types are allowed for the deserialization, see: [About language modes][2]

• Any type that is not allowed by the given language mode, will be omitted leaving a bare [ValueType], [String], [Array] or [HashTable].
• Any variable that is not $True, $False or $Null will be converted to a literal string, e.g. $Test.

Caution

In full language mode, ConvertTo-Expression permits all type initializers. Cmdlets, functions, CIM commands, and workflows will not be invoked by the ConvertFrom-Expression cmdlet.

Take reasonable precautions when using the Invoke-Expression -LanguageMode Full command in scripts. Verify that the class types in the expression are safe before instantiating them. In general, it is best to design your configuration expressions with restricted or constrained classes, rather than allowing full freeform expressions.

Type:	PSLanguageMode
Mandatory:	False
Position:	Named
Default value:	'Restricted'
Accept pipeline input:	False
Accept wildcard characters:	False

-ListAs <Object>

If supplied, the array subexpression @( ) syntaxes without an type initializer or with an unknown or denied type initializer will be converted to the given list type.

Type:	Object
Mandatory:	False
Position:	Named
Default value:
Accept pipeline input:	False
Accept wildcard characters:	False

-MapAs <Object>

If supplied, the Hash table literal syntax @{ } syntaxes without an type initializer or with an unknown or denied type initializer will be converted to the given map (dictionary or object) type.

Type:	Object
Mandatory:	False
Position:	Named
Default value:
Accept pipeline input:	False
Accept wildcard characters:	False