{"id":82645,"date":"2017-12-20T00:01:57","date_gmt":"2017-12-20T08:01:57","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/?p=82645"},"modified":"2019-02-18T09:10:02","modified_gmt":"2019-02-18T16:10:02","slug":"script-wars-the-farce-awakens-part-iii","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/script-wars-the-farce-awakens-part-iii\/","title":{"rendered":"Script Wars: The Farce Awakens (part III)"},"content":{"rendered":"

Summary:<\/strong> When last we saw our hero, Rey Skyworker, she was aiding her new co-worker, Tin. They managed to implement better error trapping by using the “Try Catch” statement in Windows PowerShell. The fact they could do this so easily it has tickled Tin’s curiosity.<\/p>\n

—————————-<\/p>\n

“Now Rey, I’m looking at this and as I see it, I could avoid the error altogether by trapping for those situations. Maybe adding in a few IF statements like this to the script.”<\/p>\n

If (($First -or $Last)) -eq ”) then<\/strong><\/p>\n

{<\/strong><\/p>\n

Write-Output ‘Names cannot be blank<\/strong><\/p>\n

}<\/strong><\/p>\n

Else<\/strong><\/p>\n

{<\/strong><\/p>\n

\u2026.rest of the script<\/strong><\/p>\n

}<\/strong><\/p>\n

Rey nodded. “You mean adding in some data validation?\u00a0 We can definitely do that, but a much better way would be to remove the READ-HOST statements, and use parameters. We can add validation directly to the parameters.”<\/p>\n

She changed the following lines from this:<\/p>\n

$First=Read-Host ‘Enter First Name’<\/strong><\/p>\n

$Last=Read-Host ‘Enter Last Name’<\/strong><\/p>\n

To this:<\/p>\n

Param(<\/strong><\/p>\n

[String]$First,<\/strong><\/p>\n

[String]$Last<\/strong><\/p>\n

)<\/strong><\/p>\n

Tin scratched his head. “How would admins run the script? Does it prompt for the information?”<\/p>\n

Rey shook her head. “First you would run the script in this fashion.”<\/p>\n

.\\NewContosoAzureUser.ps1 -First ‘John’ -Last ‘Smith’<\/strong><\/p>\n

“In this setup, you now do create users in bulk, by grabbing data from another source and sending it to the script from the command line.”<\/p>\n

Ben looked down. “That’s a great improvement. But in the short term, we have a lot of techs trained on the manual approach. How can this be adapted to meet those needs?”<\/p>\n

“By using validation on the parameters.” Rey looked up. “In this setup, we can define that the values are permitted to be null or not, assign minimum\/maximum lengths, and even specify the object type. In the example above, these objects will default as a [String] type.”<\/p>\n

Rey keyed into the PowerShell console the following line, to show how to leverage parameters in an Advanced function.<\/p>\n

Get-Help About_Functions_Advanced_Parameters <\/strong><\/p>\n

Drilling through the content, she found a good example of what she was looking for. “Ah! Here we go. The ability to ensure the parameter cannot be empty or null.”<\/p>\n

\"Screenshot<\/a><\/p>\n

Tin looked over. “Hang on, that seems too easy. If I just do this change to the code.”<\/p>\n

Rey nodded. “It actually is. So first, if we just want to ensure that $First is never a blank and is a required value, we would add in this.”<\/p>\n

She altered the beginning block of code from this:<\/p>\n

Param(<\/strong><\/p>\n

[String]$First,<\/strong><\/p>\n

[String]$Last<\/strong><\/p>\n

)<\/strong><\/p>\n

 <\/p>\n

To this:<\/p>\n

Param(<\/strong><\/p>\n

[Parameter(Mandatory=$true)]<\/strong><\/p>\n

[ValidateNotNullOrEmpty()]<\/strong><\/p>\n

[String]$First,<\/strong><\/p>\n

[String]$Last<\/strong><\/p>\n

)<\/strong><\/p>\n

\u2026And then re-ran his script without providing any values to see the result. They hit enter when it prompted for “First:”<\/p>\n

\"Screenshot<\/a><\/p>\n

Tin was jumping up and down excitedly. “This is too awesome! So if anybody makes a mistake, I can actually TRAP for it BEFORE it tries to use the bad data? Hey, wait, I think I can do the second parameter!”<\/p>\n

Tin added the additional lines for $Last to force it to be required information.<\/p>\n

Param(<\/strong><\/p>\n

[Parameter(Mandatory=$true)]<\/strong><\/p>\n

[ValidateNotNullOrEmpty()]<\/strong><\/p>\n

[String]$First,<\/strong><\/p>\n

[Parameter(Mandatory=$true)]<\/strong><\/p>\n

[ValidateNotNullOrEmpty()]<\/strong><\/p>\n

[String]$Last<\/strong><\/p>\n

)<\/strong><\/p>\n

“Now hang on\u2026 I just realized something. We do have the occasional account that doesn’t need a last name. Ones like ‘Marketing’ or ‘Finance.’ How can we ensure there is<\/em> a value, and allow that one to be not assigned by the user?”<\/p>\n

To identify the solution, Rey scanned through the help from About_Functions_Advanced_Parameters<\/strong>. “Ah! Here it is. Remove the ‘NotNullOrEmpty’ and replace it with ‘AllowEmptyString’. In this scenario, it will still prompt, but allow the value to be a blank.”<\/p>\n

Param(<\/strong><\/p>\n

[Parameter(Mandatory=$true)]<\/strong><\/p>\n

[ValidateNotNullOrEmpty()]<\/strong><\/p>\n

[String]$First,<\/strong><\/p>\n

[Parameter(Mandatory=$true)]<\/strong><\/p>\n

[AllowEmptyString()]<\/strong><\/p>\n

[String]$Last<\/strong><\/p>\n

)<\/strong><\/p>\n

They re-ran the script to see the results, supplying a value for $First when prompted, and nothing for $Last.<\/p>\n

\"Screenshot<\/a><\/p>\n

Ben looked over. “Looks like the pair of you will make a great team in this battle to smooth out our processes!”<\/p>\n

Just as Ben finished talking, TB-7 decided to start chomping on Rey’s shoelaces.<\/p>\n

Return tomorrow for another exciting adventure in “Script Wars.” There will be more exciting PowerShell coolness, and we hope Rey will get her shoelaces back.<\/p>\n

Sean Kearney, Premier Field Engineer<\/strong><\/p>\n

Enterprise Services Delivery, Secure Infrastructure<\/strong><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Summary: When last we saw our hero, Rey Skyworker, she was aiding her new co-worker, Tin. They managed to implement better error trapping by using the “Try Catch” statement in Windows PowerShell. The fact they could do this so easily it has tickled Tin’s curiosity. —————————- “Now Rey, I’m looking at this and as I […]<\/p>\n","protected":false},"author":596,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[568],"tags":[3,154,45],"class_list":["post-82645","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hey-scripting-guy","tag-scripting-guy","tag-sean-kearney","tag-windows-powershell"],"acf":[],"blog_post_summary":"

Summary: When last we saw our hero, Rey Skyworker, she was aiding her new co-worker, Tin. They managed to implement better error trapping by using the “Try Catch” statement in Windows PowerShell. The fact they could do this so easily it has tickled Tin’s curiosity. —————————- “Now Rey, I’m looking at this and as I […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/82645","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/users\/596"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=82645"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/82645\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media\/87096"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media?parent=82645"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=82645"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=82645"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}