about_Data_Sections

Artikkeli
12/13/2022

Short description

Explains Data sections, which isolate text strings and other read-only data from script logic.

Long description

Scripts that are designed for PowerShell can have one or more Data sections that contain only data. You can include one or more Data sections in any script, function, or advanced function. The content of the Data section is restricted to a specified subset of the PowerShell scripting language.

Separating data from code logic makes it easier to identify and manage both logic and data. It lets you have separate string resource files for text, such as error messages and Help strings. It also isolates the code logic, which facilitates security and validation tests.

In PowerShell, the Data section is used to support script internationalization. You can use Data sections to make it easier to isolate, locate, and process strings that will be translated into many user interface (UI) languages.

The Data section is a PowerShell 2.0 feature. Scripts with Data sections will not run in PowerShell 1.0 without revision.

Syntax

The syntax for a Data section is as follows:

DATA [<variable-name>] [-supportedCommand <cmdlet-name>] {
    <Permitted content>
}

The Data keyword is required. It is not case-sensitive. The permitted content is limited to the following elements:

All PowerShell operators, except -match
If, Else, and ElseIf statements
The following automatic variables: $PsCulture, $PsUICulture, $True, $False, and $Null
Comments
Pipelines
Statements separated by semicolons (;)

Literals, such as the following:

a
1
1,2,3
"PowerShell 2.0"
@( "red", "green", "blue" )
@{ a = 0x1; b = "great"; c ="script" }
[XML] @'
<p> Hello, World </p>
'@

Cmdlets that are permitted in a Data section. By default, only the ConvertFrom-StringData cmdlet is permitted.
Cmdlets that you permit in a Data section by using the -SupportedCommand parameter.

When you use the ConvertFrom-StringData cmdlet in a Data section, you can enclose the key-value pairs in single-quoted or double-quoted strings or in single-quoted or double-quoted here-strings. However, strings that contain variables and subexpressions must be enclosed in single-quoted strings or in single-quoted here-strings so that the variables are not expanded and the subexpressions are not executable.

-SupportedCommand

The -SupportedCommand parameter allows you to indicate that a cmdlet or function generates only data. It is designed to allow users to include cmdlets and functions in a data section that they have written or tested.

The value of -SupportedCommand is a comma-separated list of one or more cmdlet or function names.

For example, the following data section includes a user-written cmdlet, Format-Xml, that formats data in an XML file:

DATA -supportedCommand Format-Xml
{
    Format-Xml -Strings string1, string2, string3
}

Using a Data Section

To use the content of a Data section, assign it to a variable and use variable notation to access the content.

For example, the following data section contains a ConvertFrom-StringData command that converts the here-string into a hash table. The hash table is assigned to the $TextMsgs variable.

The $TextMsgs variable is not part of the data section.

$TextMsgs = DATA {
    ConvertFrom-StringData -StringData @'
Text001 = Windows 7
Text002 = Windows Server 2008 R2
'@
}

To access the keys and values in hash table in $TextMsgs, use the following commands.

$TextMsgs.Text001
$TextMsgs.Text002

Alternately, you can put the variable name in the definition of the Data section. For example:

DATA TextMsgs {
    ConvertFrom-StringData -StringData @'
Text001 = Windows 7
Text002 = Windows Server 2008 R2
'@
}

$TextMsgs

The result is the same as the previous example.

Name                           Value
----                           -----
Text001                        Windows 7
Text002                        Windows Server 2008 R2

Examples

Simple data strings.

DATA {
    "Thank you for using my PowerShell Organize.pst script."
    "It is provided free of charge to the community."
    "I appreciate your comments and feedback."
}

Strings that include permitted variables.

DATA {
    if ($null) {
        "To get help for this cmdlet, type get-help new-dictionary."
    }
}

A single-quoted here-string that uses the ConvertFrom-StringData cmdlet:

DATA {
    ConvertFrom-StringData -stringdata @'
Text001 = Windows 7
Text002 = Windows Server 2008 R2
'@
}

A double-quoted here-string that uses the ConvertFrom-StringData cmdlet:

DATA  {
    ConvertFrom-StringData -stringdata @"
Msg1 = To start, press any key.
Msg2 = To exit, type "quit".
"@
}

A data section that includes a user-written cmdlet that generates data:

DATA -supportedCommand Format-XML {
    Format-Xml -strings string1, string2, string3
}

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