How to parse a here-string in PowerShell as a hash? - string

Question

This example is easy enough:
PS C:\Users\saunders\Desktop\misc>
PS C:\Users\saunders\Desktop\misc> $hash = #"
>> Name = Jackson
>> Employer = BigData
>> EmpID = 2032
>> Type = Permanent
>> "#
PS C:\Users\saunders\Desktop\misc>
PS C:\Users\saunders\Desktop\misc> $hash
Name = Jackson
Employer = BigData
EmpID = 2032
Type = Permanent
PS C:\Users\saunders\Desktop\misc>
PS C:\Users\saunders\Desktop\misc> $hash | ConvertFrom-StringData
Name Value
---- -----
Employer BigData
Type Permanent
EmpID 2032
Name Jackson
PS C:\Users\saunders\Desktop\misc>
Which is excellent and the desired output. Here:
PS C:\Users\saunders\Desktop\misc>
PS C:\Users\saunders\Desktop\misc> cat .\hash.txt
$hash = #"
Name = Jackson
Employer = BigData
EmpID = 2032
Type = Permanent
"#
PS C:\Users\saunders\Desktop\misc>
PS C:\Users\saunders\Desktop\misc> $foo = Get-Content .\hash.txt
PS C:\Users\saunders\Desktop\misc>
PS C:\Users\saunders\Desktop\misc> $foo
$hash = #"
Name = Jackson
Employer = BigData
EmpID = 2032
Type = Permanent
"#
PS C:\Users\saunders\Desktop\misc>
the data originates in a file. How is this file read as a here-string so that it can be used as above?

Answer 1

Your .\hash.txt is in effect a .ps1 script file, so you could change its extension an then load it via ., the dot-sourcing operator, at which point $hash will be defined and can be passed to ConvertFrom-StringData.
To process the file as-is, you can pass its content to Invoke-Expression (though note that this cmdlet should generally be avoided):
Invoke-Expression (Get-Content -Raw t.txt)
$hash | ConvertFrom-StringData
If you have control over how .\hash.txt gets created and can change its name, you can save it as a PowerShell data file, i.e. with extension .psd1, which can be read as-is with the Import-PowerShellDataFile cmdlet:
A .psd1 file is in effect the source-code representation of a hashtable literal, whose syntax requirements are more stringent than for text that can be parsed with ConvertFrom-StringData:
# Save the source-code representation of a hashtable literal
# to a file - do NOT include a variable assignment:
#'
#{
Name = 'Jackson'
Employer = 'BigData'
EmpID = 2032
Type = 'Permanent'
}
'# > hash.psd1
Import-PowerShellDataFile hash.psd1
As an aside:
As of PowerShell 7.3.2, both ConvertFrom-StringData and Import-PowerShellData do not preserve the entries in definition order, given that [hasthable] instances are inherently unordered.
GitHub issue #19070 proposes overcoming this limitation, by making these cmdlets return ordered hashtables instead, via System.Management.Automation.OrderedHashtable, which derives from [hashtable].