PowerShell: How to initialize an array of custom o

问题:

First, as this leads to my question, I'll start by noting that I've worked with XML a fair bit in PowerShell, and like how I can read data from XML files, quickly, into arrays of custom objects. For example, if I had the following XML file:

<stuff>
 <item name="Joe" age="32">
  <info>something about him</info>
 </item>
 <item name="Sue" age="29">
  <info>something about her</info>
 </item>
 <item name="Cat" age="12">
  <info>something else</info>
 </item>
</stuff>

And if I read it in simply, like this:

[xml]$myxml = Get-Content .\my.xml

Then I can get to an array of my items like this:

[array]$myitems = $myxml.stuff.Item
$myitems

name   age  info
----   ---  ----
Joe    32   something about him
Sue    29   something about her
Cat    12   something else

So, now my question:

How can I create a similar structure of an array of custom objects, and initialize them in my script, without reading a file?

I can do lots of looping and/or lots of creating/initializing individual objects, and then add to an array one at a time...

But it seems there should be a way to perform this creation/initialization in a simpler way. Note that the key here, is that my custom objects have more than two elements (otherwise, I'd have used a hash).

I've even looked at creating a big string of XML, and using Select-XML, but I just couldn't get the syntax right (if that was even the right road to be heading down).

回答1:

I'd do something along these lines:

$myitems =
@([pscustomobject]@{name="Joe";age=32;info="something about him"},
[pscustomobject]@{name="Sue";age=29;info="something about her"},
[pscustomobject]@{name="Cat";age=12;info="something else"})

Note that this only works in PowerShell 3, but since you did not mention the version in your question I'm assuming this does not matter for you.

回答2:

Here is a concise way to initialize an array of custom objects in PowerShell.

> $body = @( @{ Prop1="1"; Prop2="2"; Prop3="3" }, @{ Prop1="1"; Prop2="2"; Prop3="3" } )
> $body

Name                           Value
----                           -----
Prop2                          2
Prop1                          1
Prop3                          3
Prop2                          2
Prop1                          1
Prop3                          3  

回答3:

Maybe you mean like this? I like to make an object and use Format-Table:

PS C:\Users\Joel> $array = @()
PS C:\Users\Joel> $object = New-Object -TypeName PSObject
PS C:\Users\Joel> $object | Add-Member -Name 'Name' -MemberType Noteproperty -Value 'Joe'
PS C:\Users\Joel> $object | Add-Member -Name 'Age' -MemberType Noteproperty -Value 32
PS C:\Users\Joel> $object | Add-Member -Name 'Info' -MemberType Noteproperty -Value 'something about him'
PS C:\Users\Joel> $array += $object
PS C:\Users\Joel> $array | Format-Table

Name                                                                        Age Info
----                                                                        --- ----
Joe                                                                          32  something about him

This will put all objects you have in the array in columns according to their properties.

Tip: Using -auto sizes the table better

PS C:\Users\Joel> $array | Format-Table -Auto

Name Age Info
---- --- ----
Joe   32 something about him

You can also specify which properties you want in the table. Just separate each property name with a comma:

PS C:\Users\Joel> $array | Format-Table Name, Age -Auto

Name Age
---- ---
Joe   32

回答4:

Here is a more concise version of the accepted answer which avoids repeating the NoteProperty identifiers and the [pscustomobject]-cast:

$myItems =  ("Joe",32,"something about him"), ("Sue",29,"something about her")
            | ForEach-Object {[pscustomobject]@{name = $_[0]; age = $_[1]; info = $_[2]}}

Result:

> $myItems

name           age         info
----           ---         ----
Joe            32          something about him
Sue            29          something about her

回答5:

The simplest way to initialize an array

Create array

$array = @()

Create your header

$line = "" | select name,age,phone

Fill the line

$line.name = "Leandro"
$line.age = "39"
$line.phone = "555-555555"

Add line to $array

$array += $line

Result

$array

name                                                     age                                                      phone
----                                                     ---                                                      -----
Leandro                                                  39                                                       555-555555

回答6:

Use a "Here-String" and cast to XML.

[xml]$myxml = @"
<stuff>
 <item name="Joe" age="32">
  <info>something about him</info>
 </item>
 <item name="Sue" age="29">
  <info>something about her</info>
 </item>
 <item name="Cat" age="12">
  <info>something else</info>
 </item>
</stuff>
"@

[array]$myitems = $myxml.stuff.Item

$myitems

回答7:

I had to create an array of a predefined type, and I successfully did as follows:

[System.Data.DataColumn[]]$myitems = ([System.Data.DataColumn]("col1"), 
                [System.Data.DataColumn]("col2"),  [System.Data.DataColumn]("col3"))