Add-Member

Syntax

Add-Member
   -InputObject <PSObject>
   -TypeName <String>
   [-PassThru]
   [<CommonParameters>]

Add-Member
   [-MemberType] <PSMemberTypes>
   [-Name] <String>
   [[-Value] <Object>]
   [[-SecondValue] <Object>]
   -InputObject <PSObject>
   [-TypeName <String>]
   [-Force]
   [-PassThru]
   [<CommonParameters>]

Add-Member
   [-NotePropertyName] <String>
   [-NotePropertyValue] <Object>
   -InputObject <PSObject>
   [-TypeName <String>]
   [-Force]
   [-PassThru]
   [<CommonParameters>]

Add-Member
   [-NotePropertyMembers] <IDictionary>
   -InputObject <PSObject>
   [-TypeName <String>]
   [-Force]
   [-PassThru]
   [<CommonParameters>]

Description

The Add-Member cmdlet lets you add members (properties and methods) to an instance of a Windows PowerShell object. For instance, you can add a NoteProperty member that contains a description of the object or a ScriptMethod member that runs a script to change the object.

To use Add-Member , pipe the object to Add-Member , or use the InputObject parameter to specify the object. Use the MemberType parameter to specify the type of member that you want to add, use the Name parameter to assign a name to the new member, and use the Value parameter to set the value of the member.

The properties and methods that you add are added only to the particular instance of the object that you specify. Add-Member does not change the object type. To create a new object type, use the Add-Type cmdlet. You can also use the Export-Clixml cmdlet to save the instance of the object, including the additional members, in a file. Then you can use the Import-Clixml cmdlet to re-create the instance of the object from the information that is stored in the exported file.

Beginning in Windows PowerShell 3.0, Add-Member has new features that make it easier to add note properties to objects. You can use the NotePropertyName and NotePropertyValue parameters to define a note property or use the NotePropertyMembers parameter, which takes a hash table of note property names and values.

Also, beginning in Windows PowerShell 3.0, the PassThru parameter, which generates an output object, is needed less frequently. Add-Member now adds the new members directly to the input object of more types. For more information, see the PassThru parameter description.

Examples

Example 1: Add a note property to a PSObject

PS C:\> $A = dir c:\ps-test\test.txt

PS C:\> $A | Add-Member -NotePropertyName Status -NotePropertyValue Done

PS C:\> $A | Add-Member Status Done

PS C:\> $A.Status

Done

These commands add the Status note property with a value of "Done" to the FileInfo object that represents the Test.txt file.

The first command uses the Get-ChildItem cmdlet (alias = "dir) to get the Test.txt file. It saves it in the $a variable.

The second and third commands add the note property to the object in $a. The third command omits the optional parameter names, so the parameter values must be in the correct Name-Value order. These commands are equivalent and can be used interchangeably.

The fourth command uses dot notation to get the value of the Status property of the object in $a. As the output shows, the value is "Done".

Example 2: Add an alias property to a PSObject

PS C:\> $A = dir c:\ps-test\test.txt

PS C:\> $A | Add-Member -MemberType AliasProperty -Name FileLength -Value Length

PS C:\> $A.FileLength

2394

These commands add the FileLength alias property to the object that represents the Test.txt file. The new property is an alias for the Length property.

The first command use the Get-ChildItem cmdlet (alias = "dir") to get the Test.txt file.

The second command adds the FileLength alias property.

The third command uses dot notation to get the value of the new FileLength property.

Example 3: Add a StringUse note property to a string

PS C:\> $A = "A string"

PS C:\>  $A = $A | Add-Member @{StringUse="Display"} -PassThru

PS C:\> $A.StringUse

Display

These commands add the StringUse note property to a string. Because Add-Member cannot add types to String input objects, the command uses the PassThru parameter to generate an output object. The last command in the example displays the new property.

The command uses the NotePropertyMembers parameter, but omits the parameter name, which is optional. The value of the NotePropertyMembers parameter is a hash table. The key is the note property name, StringUse , and the value is the note property value, Display.

Example 4: Add a script method to a string object

PS C:\> $A = "This is a string."

PS C:\> $A = Add-Member -InputObject $A -MemberType ScriptMethod -Name "PadBoth" -Value {$P = $this.PadLeft($this.Length + 1); $p.PadRight($p.Length + 1)} -PassThru

PS C:\> $A.Padboth()

This is a string.

These commands add the PadBoth script method to a string object.

The first command creates a string and saves it in the $A variable.

The second command adds the Padboth script method to the object in the $A variable. The Value parameter defines the new script method. It uses the PadRight and PadLeft methods of a string to add one space the left and one space to the right of the string.

The Value parameter also uses the $This automatic variable, which represents the current object. The $This variable is valid only in script blocks that define new properties and methods.

The command includes the PassThru parameter, which directs Add-Member to return an instance of the object that includes the new script property. By default, Add-Member adds members to PSObject s and does not generate any output.

The third command uses dot notation to call the new PadBoth script method on the object in the $A variable.

Example 5: Add an alias property to an event

PS C:\> $Event = Get-EventLog -LogName System -Newest 1

PS C:\> $Event.TimeWritten | Get-MemberTypeName: System.DateTime

Name                 MemberType     Definition

----                 ----------     ----------

Add                  Method         System.DateTime Add(System.TimeSpan value)

AddDays              Method         System.DateTime AddDays(double value)

AddHours             Method         System.DateTime AddHours(double value)

AddMilliseconds      Method         System.DateTime AddMilliseconds(double value)

AddMinutes           Method         System.DateTime AddMinutes(double value)...



PS C:\> Add-Member -InputObject $Event -MemberType AliasProperty -Name When -Value TimeWritten -SecondValue System.String

PS C:\> $Event.When | Get-MemberTypeName: System.String



Name             MemberType            Definition

----             ----------            ----------

Clone            Method                System.Object Clone()

CompareTo        Method                int CompareTo(System.Object value), int CompareTo(string strB)

Contains         Method                bool Contains(string value)

These commands add the When alias property to an event in the System event log. The event is an EventLogEntry object that is returned by the Get-EventLog cmdlet.

The When alias property is an alias for the TimeWritten property of the object. The SecondValue parameter is used to specify that the property value should be converted to type System.String when accessed by using the AliasProperty . The TimeWritten property is a DateTime object.

The first command uses the Get-EventLog cmdlet to get the newest event in the System event log. It stores the event in the $Event variable.

To demonstrate that the TimeWritten property is a DateTime type, the second command uses dot notation to get the TimeWritten property of that event and pipes it to the Get-Member cmdlet.

The third command uses the Add-Member cmdlet to add the When alias property to the object instance in the $Event variable. The Name parameter assigns the name, When, and the Value parameter specifies that When is an alias for the TimeWritten property. The SecondValue parameter indicates that the value that the When method returns should be cast to a System.String type.

The fourth command uses dot notation to call the new When method. The command pipes the method value to the Get-Member cmdlet to confirm that it has returned a string.

Example 6: Copy all properties of an object to another

PS C:\> function Copy-Property ($From, $To)

{     foreach ($p in Get-Member -InputObject $From -MemberType Property)

  {     Add-Member -InputObject $To -MemberType NoteProperty -Name $p.Name

     -Value $From.$($p.Name) -Force     $To.$($p.Name) = $From.$($p.Name)

  }

}

This function copies all of the properties of one object to another object.

The first command in the function declares the function name and lists its parameters.

The ForEach loop uses the Get-Member cmdlet to get each of the properties of the From object. The commands within the ForEach loop are performed in series on each of the properties.

The Add-Member command adds the property of the From object to the To object as a NoteProperty. It uses the Force parameter to add members with the same member name.

The last command in the function gives the new property the same name as the original property.

Example 7: Create a custom object

PS C:\> $Asset = New-Object -TypeName PSObject

PS C:\> $d = [ordered]@{Name="Server30";System="Server Core";PSVersion="4.0"}

PS C:\> $Asset | Add-Member -NotePropertyMembers $d -TypeName Asset

PS C:\> $Asset | Get-Member   TypeName: Asset

Name        MemberType   Definition

----        ----------   ----------

Equals      Method       bool Equals(System.Object obj) GetHashCode Method       int GetHashCode()

GetType     Method       type GetType()

ToString    Method       string ToString()

Name        NoteProperty System.String Name=Server30

PSVersion   NoteProperty System.String PSVersion=4.0

System      NoteProperty System.String System=Server Core

This example creates the Asset custom object.

The first command uses the New-Object cmdlet to create a PSObject . The command saves the PSObject in the $Asset variable.

The second command uses the [ordered] type accelerator to create an ordered dictionary of names and values. The command saves the result in the $D variable.

The third command uses the NotePropertyMembers parameter of the Add-Member cmdlet to add the dictionary in the $D variable to the PSObject . It uses the TypeName property to assign a new name, Asset, to the PSObject .

The fourth command sends the new Asset object in the $Asset variable to the Get-Member cmdlet. The output shows that the object has a type name of "Asset" and the note properties that we defined in the ordered dictionary.

Required Parameters

Optional Parameters

Inputs

System.Management.Automation.PSObject

You can pipe any object type to this cmdlet.

Outputs

None or System.Object

When you use the PassThru parameter, this cmdlet returns the newly-extended object. Otherwise, this cmdlet does not generate any output.

Notes

You can add members only to PSObject objects. To determine whether an object is a PSObject object, use the "is" operator. For instance, to test an object stored in the $obj variable, type $obj -is \[PSObject\] .

The names of the MemberType , Name , Value , and SecondValue parameters are optional. If you omit the parameter names, the unnamed parameter values must appear in this order: MemberType , Name , Value , and SecondValue . If you include the parameter names, the parameters can appear in any order.

You can use the $this automatic variable in script blocks that define the values of new properties and methods. The $this variable refers to the instance of the object to which the properties and methods are being added. For more information about the $this variable, see about_Automatic_Variables.

Related Links

• Export-Clixml
• Get-Member
• Import-Clixml
• New-Object