Import-Module works only when piped from Get-Module

Question

I wrote a simple PowerShell module. I need to keep more versions of the module. ~~All paths to versions are added to $env:PSModulePath.~~ I'm facing strange problem when importing the module to my session.

This fails:

Import-Module Contoso.PowerShell -RequiredVersion "0.0.2"

Import-Module : The specified module 'Contoso.PowerShell' with version '0.0.2'
was not loaded because no valid module file was found in any module directory.
At line:1 char:1
+ Import-Module Contoso.PowerShell -RequiredVersion "0.0.2"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ResourceUnavailable: (Contoso.PowerShell:String) [Import-Module], FileNotFoundException
    + FullyQualifiedErrorId : Modules_ModuleWithVersionNotFound,Microsoft.PowerShell.Commands.ImportModuleCommand

And now the strange thing - the module with the "0.0.2" version exists. I can successfully list it (with Get-Module -ListAvailable). I can even import it and work with it, but the only way how to do it is this:

Get-Module Contoso.PowerShell -ListAvailable |
    ? { $_.Version -eq "0.0.2" } |
    Import-Module

Everything works like a charm then. The question is: WHY? I'd like to be able to import the module with the first simple command.

EDIT:

Here is how I store the versions of the module:

 Get-Module Contoso.PowerShell -ListAvailable

    Directory: C:\Program Files\WindowsPowerShell\Modules\Contoso.PowerShell\Contoso.PowerShell.0.0.1


ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     0.0.1      Contoso.PowerShell


    Directory: C:\Program Files\WindowsPowerShell\Modules\Contoso.PowerShell\Contoso.PowerShell.0.0.2


ModuleType Version    Name                                ExportedCommands
---------- -------    ----                                ----------------
Script     0.0.2      Contoso.PowerShell

And sorry for confusion - I do NOT have paths to each version in the PSModulePath environment variable.

briantist briantist · Accepted Answer · 2018-03-05T22:23:19

The reason Import-Module works is because it uses a different parameter set; one where it accepts one or more [PSModuleInfo] objects, which are what Get-Module returns.

Likely, it uses the work already done by Get-Module to determine which file to load.

The next question then is "why doesn't Import-Module find the version the same way Get-Module does?" and the answer to that is "I don't know."

~~While they should be consistent in any case, a possible cause for trouble is your directly structure. How are you storing multiple versions?~~

It looks to me like your module paths are incorrect.

Your structure should be:

Contoso.PowerShell\0.0.2
Contoso.PowerShell\0.0.3

etc.

The module files go directly in the version number folder, and it shouldn't additionally have the name inside it.

You can see this structure by using Install-Module to install one from a repository and taking a look at how it handles it.

Import-Module works only when piped from Get-Module

1 Answers