Powershell: storing variables to a file [duplicate] - powershell

Question

I would like to write out a hash table to a file with an array as one of the hash table items. My array item is written out, but it contains files=System.Object[]
Note - Once this works, I will want to reverse the process and read the hash table back in again.
clear-host
$resumeFile="c:\users\paul\resume.log"
$files = Get-ChildItem *.txt
$files.GetType()
write-host
$types="txt"
$in="c:\users\paul"
Remove-Item $resumeFile -ErrorAction SilentlyContinue
$resumeParms=#{}
$resumeParms['types']=$types
$resumeParms['in']=($in)
$resumeParms['files']=($files)
$resumeParms.GetEnumerator() | ForEach-Object {"{0}={1}" -f $_.Name,$_.Value} | Set-Content $resumeFile
write-host "Contents of $resumefile"
get-content $resumeFile
Results
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Object[] System.Array
Contents of c:\users\paul\resume.log
files=System.Object[]
types=txt
in=c:\users\paul

Answer 1

The immediate fix is to create your own array representation, by enumerating the elements and separating them with ,, enclosing string values in '...':
# Sample input hashtable. [ordered] preserves the entry order.
$resumeParms = [ordered] #{ foo = 42; bar = 'baz'; arr = (Get-ChildItem *.txt) }
$resumeParms.GetEnumerator() |
ForEach-Object {
"{0}={1}" -f $_.Name, (
$_.Value.ForEach({
(("'{0}'" -f ($_ -replace "'", "''")), $_)[$_.GetType().IsPrimitive]
}) -join ','
)
}
Not that this represents all non-primitive .NET types as strings, by their .ToString() representation, which may or may not be good enough.
The above outputs something like:
foo=42
bar='baz'
arr='C:\Users\jdoe\file1.txt','C:\Users\jdoe\file2.txt','C:\Users\jdoe\file3.txt'
See the bottom section for a variation that creates a *.psd1 file that can later be read back into a hashtable instance with Import-PowerShellDataFile.
Alternatives for saving settings / configuration data in text files:
If you don't mind taking on a dependency on a third-party module:
Consider using the PSIni module, which uses the Windows initialization file (*.ini) file format; see this answer for a usage example.
Adding support for initialization files to PowerShell itself (not present as of 7.0) is being proposed in GitHub issue #9035.
Consider using YAML as the file format; e.g., via the FXPSYaml module.
Adding support for YAML files to PowerShell itself (not present as of 7.0) is being proposed in GitHub issue #3607.
The Configuration module provides commands to write to and read from *.psd1 files, based on persisted PowerShell hashtable literals, as you would declare them in source code.
Alternatively, you could modify the output format in the code at the top to produce such files yourself, which allows you to read them back in via
Import-PowerShellDataFile, as shown in the bottom section.
As of PowerShell 7.0 there's no built-in support for writing such as representation; that is, there is no complementary Export-PowerShellDataFile cmdlet.
However, adding this ability is being proposed in GitHub issue #11300.
If creating a (mostly) plain-text file is not a must:
The solution that provides the most flexibility with respect to the data types it supports is the XML-based CLIXML format that Export-Clixml creates, as Lee Dailey suggests, whose output can later be read with Import-Clixml.
However, this format too has limitations with respect to type fidelity, as explained in this answer.
Saving a JSON representation of the data, as Lee also suggests, via ConvertTo-Json / ConvertFrom-Json, is another option, which makes for human-friendlier output than XML, but is still not as friendly as a plain-text representation; notably, all \ chars. in file paths must be escaped as \\ in JSON.
Writing a *.psd1 file that can be read with Import-PowerShellDataFile
Within the stated constraints regarding data types - in essence, anything that isn't a number or a string becomes a string - it is fairly easy to modify the code at the top to write a PowerShell hashtable-literal representation to a *.psd1 file so that it can be read back in as a [hashtable] instance via Import-PowerShellDataFile:
As noted, if you don't mind installing a module, consider the Configuration module, which has this functionality built int.
# Sample input hashtable.
$resumeParms = [ordered] #{ foo = 42; bar = 'baz'; arr = (Get-ChildItem *.txt) }
# Create a hashtable-literal representation and save it to file settings.psd1
#"
#{
$(
($resumeParms.GetEnumerator() |
ForEach-Object {
" {0}={1}" -f $_.Name, (
$_.Value.ForEach({
(("'{0}'" -f ($_ -replace "'", "''")), $_)[$_.GetType().IsPrimitive]
}) -join ','
)
}
) -join "`n"
)
}
"# > settings.psd1
If you read settings.psd1 with Import-PowerShellDataFile settings.psd1 later, you'll get a [hashtable] instance whose entries you an access as usual and which produces the following display output:
Name Value
---- -----
bar baz
arr {C:\Users\jdoe\file1.txt, C:\Users\jdoe\file1.txt, C:\Users\jdoe\file1.txt}
foo 42
Note how the order of entries (keys) was not preserved, because hashtable entries are inherently unordered.
On writing the *.psd1 file you can preserve the key(-creation) order by declaring the input hashtable (System.Collections.Hashtable) as [ordered], as shown above (which creates a System.Collections.Specialized.OrderedDictionary instance), but the order is, unfortunately, lost on reading the *.psd1 file.
As of PowerShell 7.0, even if you place [ordered] before the opening #{ in the *.psd1 file, Import-PowerShellDataFile quietly ignores it and creates an unordered hashtable nonetheless.

Answer 2

This is a problem I deal with all the time and it drives me mad. I really think that there should be a function specifically for this action... so I wrote one.
function ConvertHashTo-CSV
{
Param (
[Parameter(Mandatory=$true)]
$hashtable,
[Parameter(Mandatory=$true)]
$OutputFileLocation
)
$hastableAverage = $NULL #This will only work for hashtables where each entry is consistent. This checks for consistency.
foreach ($hashtabl in $hashtable)
{
$hastableAverage = $hastableAverage + $hashtabl.count #Counts the amount of headings.
}
$Paritycheck = $hastableAverage / $hashtable.count #Gets the average amount of headings
if ( ($parity = $Paritycheck -is [int]) -eq $False) #if the average is not an int the hashtable is not consistent
{
write-host "Error. Hashtable is inconsistent" -ForegroundColor red
Start-Sleep -Seconds 5
return
}
$HashTableHeadings = $hashtable[0].GetEnumerator().name #Get the hashtable headings
$HashTableCount = ($hashtable[0].GetEnumerator().name).count #Count the headings
$HashTableString = $null # Strange to hold the CSV
foreach ($HashTableHeading in $HashTableHeadings) #Creates the first row containing the column headings
{
$HashTableString += $HashTableHeading
$HashTableString += ", "
}
$HashTableString = $HashTableString -replace ".{2}$" #Removed the last , added by the above loop in error
$HashTableString += "`n"
foreach ($hashtabl in $hashtable) #Adds the data
{
for($i=0;$i -lt $HashTableCount;$i++)
{
$HashTableString += $hashtabl[$i]
if ($i -lt ($HashTableCount - 1))
{
$HashTableString += ", "
}
}
$HashTableString += "`n"
}
$HashTableString | Out-File -FilePath $OutputFileLocation #writes the CSV to a file
}
To use this copy the function into your script, run it, and then
ConvertHashTo-CSV -$hashtable $Hasharray -$OutputFileLocation c:\temp\data.CSV
The code is annotated but a brief explanation of what it does. Steps through the arrays and hashtables and adds them to a string adding the required formatting to make the string a CSV file, then outputs that to a file.
The main limitation of this is that the Hashtabes in the array all have to contain the same amount of fields. To get around this if a hashtable has a field that doesnt contain data ensure it contains at least a space.
More on this can be found here : https://grumpy.tech/powershell-convert-hashtable-to-csv/