Use PowerShell Parameter Validation instead of manual parameter validation

[thedavecarroll]

Use PowerShell Parameter Validation instead of manual parameter validation

[Windos]

Personally, I would vote fail (which validate count will do). That'd give me output saying "hey fool, you can only give me 100 of these" then I know I have to batch them in the code on my end.

[thedavecarroll]

On a few of the functions, I was using the private function New-ValidationErrorRecord to generate a cleaner error record when the provided parameters were not valid. I believe this private function was created after Get-TwitterFollowers.

Parameter validation is definitely something that needs to be addressed.

Here is where some confusion creeps in:

Get-TwitterFollowers connects to the following two endpoints. The maximum and default ResultsPerPage for each endpoint is different.

Endpoint	ResultsPerPage Max	ResultsPerPage Default
followers/list.json	200	50
followers/ids.json	5000	5000

I'll need to see how to implement the two defaults and maximum values within a ValidateScript. Since the endpoint is determined by the ParameterSetName, I'm not sure if I can use that in a ValidateScript.

I've asked Twitter. Hopefully, someone can provide some insight.

Thanks

[thedavecarroll]

Additionally, there are some parameters that can accept an array, but the array cannot exceed a certain count.

During the ValidateScript, the count of the array is not available.

Instead of returning with a warning, which is the current behavior, we could simply warn that anything over the maximum count will be truncated. This would need to be handled within the body of the function.

Get-TwitterFriendship -ScreenName $Names
WARNING: More than 100 ScreenNames provided. Processing the first 100 only.

[Windos]

For those array ones, remember that you can include multiple validation options:

param (
    [ValidateCount(1,3)] # Needs at least object, but can include up to three
    [ValidateNotNullOrEmpty()]
    [ValidateScript({Test-Item $_})]
    [string[]] $Name
)

As a user I'd prefer to be told upfront if I've included an array that's too long, and I should go and fix my code to break it up (as having the cmdlet truncate the array for me could be iffy when I try to figure out "ok... which ones do I need to re do?")

[thedavecarroll]

Wowzers! [ValidateCount()] satisfies UserId and ScreenName quite nicely!

So, the question would be: terminating failure over 100 OR warning over 100?

What do you think @Windos ?

[RobinDadswell]

I would also vote for fail (by using validate count) as it makes it more clear that something is wrong as opposed to not getting all the data and potentially not seeing the yellow warning