How to read attribute values from XML nodes with Powershell-CodePudding

I'm currently trying to get a Powershell script to extract information from an XML file and I've been trying a few different things like Select-Xml and SelectNodes, but I'm struggling. The information is in a format like this:

<school>
   <students>
      <student name="Bob" subject="Math" year="5">
         <details SID="38571273" code="1122" group="" />
      </student>
        
      <student name="John" subject="Science" year="5">
         <details SID="38343555" code="1123" group="" />
      </student>
   </students>
</school>

I want to extract information like the name, subject, year, SID, code, and group and store it in an array for each student so I can process it. I'm writing a Powershell script to do this, but I'm quite new to it, as well as XML. Any help would be greatly appreciated!

CodePudding user response：

For simple tasks like this one, you can access the XML items with dot notation, i.e. $xml.school.students.student will give an array of <student> elements.

After that, you can use select (aka Select-Object) to pick out certain properties. Either direct properties by name, or name/expression pairs (@{name='...', expression={...}} for more complex ones, or if you want to rename the result "columns":

$xml.school.students.student | select name,subject,year,@{n='SID'; e={$_.details.SID}}

gives an array of PSCustomObjects:

name subject year SID     
---- ------- ---- ---     
Bob  Math    5    38571273
John Science 5    38343555

CodePudding user response：

With the updated XML I revised my answer -

I think this is what you're looking for. You would just have to update the path to your xml.

$XMLPath = "ENTER_PATH"
function Get-StudentInfo {
    param (
        $xPATH,
        $title)
    Select-Xml -Path $XMLPath -XPath "/school/students/$xPATH" | ForEach-Object { $_.Node.$title }
}

$students = [PSCustomObject]@{
    Names    = Get-StudentInfo -xPath "student" -title "name"
    Subjects = Get-StudentInfo -xPath "student" -title "subject"
    Years    = Get-StudentInfo -xPath "student" -title "year"
    SIDs     = Get-StudentInfo -xPath "student/details" -title "SID"
    Codes    = Get-StudentInfo -xPath "student/details" -title "code"
    Groups   = Get-StudentInfo -xPath "student/details" -title "group"
}

$students.Names

From there you would have an object $students that has properties with an array for each property.

Names    : {Bob, John}
Subjects : {Math, Science}
Years    : {5, 5}
SIDs     : {38343555, 38343555}
Codes    : {1123, 1123}
Groups   : {, }

To get a list of all the students names you would use $students.names or for subject $students.subjects

A version that loads the XML file only once, instead of once per call to Get-StudentInfo:

$students = Select-Xml -Path "test.xml" -XPath '/school/students/student' | Select-Object @(
    @{name='Name';    expr={ $_ | Select-Xml '@name' }}
    @{name='Subject'; expr={ $_ | Select-Xml '@subject' }}
    @{name='Year';    expr={ $_ | Select-Xml '@year' }}
    @{name='SID';     expr={ $_ | Select-Xml 'details/@SID' }}
    @{name='Code';    expr={ $_ | Select-Xml 'details/@code' }}
    @{name='Group';   expr={ $_ | Select-Xml 'details/@group' }}
)
$students

result

Name Subject Year SID      Code Group
---- ------- ---- ---      ---- -----
Bob  Math    5    38571273 1122      
John Science 5    38343555 1123