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Asynchronous Refresh


Shows how to implement Tab Completion with values that are refreshed in the background.


When providing values for tab completion, one of the frequent issues is that retrieving he values can take a lot of time. Too much for the average user to tolerate (how much fun is a 5 seconds freeze after hitting Tab, huh?).

One option to deal with this is to load the data once and cache it. That is better, but now the data will grow stale. Now if it is not too critical that the data in question be up-to-date, that may be acceptable to you, however it would be more elegant if you could do refreshes of the data in the background, so the user doesn’t notice.

Fortunately, the PSFramework module has a solution for this that makes it fast to implement:

Defining the Refresh

Register-PSFTaskEngineTask -Name ComputerCacheRefresh -Interval (New-TimeSpan -Minutes 5) -ScriptBlock {
    Set-PSFTaskEngineCache -Module MyModule -Name Computers -Value (Get-ADComputer -Filter *).Name

This example will execute every 5 minutes, storing the results of (Get-ADComputer -Filter *).Name in the cache under the module MyModule and name Computers.

Defining Tab Completion

Register-PSFTeppScriptblock -Name ADComputer -ScriptBlock {
    Get-PSFTaskEngineCache -Module MyModule -Name Computers
Register-PSFTeppArgumentCompleter -Command Get-Something -Parameter ComputerName -Name ADComputer

As was covered in the Tab Completion guide, you need to define a scriptblock and then assign it to command and parameter that should use it. Using Get-PSFTaskEngineCache -Module MyModule -Name Computers during the Tab Completion scriptblock retrieves the information stored in the cache.


Back to Tab Expansion

Version 1.0
Written on: 2018-07-06
Updated on: 2018-07-06