{"id":2306,"date":"2012-05-15T08:18:41","date_gmt":"2012-05-15T12:18:41","guid":{"rendered":"http:\/\/jdhitsolutions.com\/blog\/?p=2306"},"modified":"2012-05-15T08:18:41","modified_gmt":"2012-05-15T12:18:41","slug":"powershell-scripting-with-validatenotnullorempty","status":"publish","type":"post","link":"https:\/\/jdhitsolutions.com\/blog\/scripting\/2306\/powershell-scripting-with-validatenotnullorempty\/","title":{"rendered":"PowerShell Scripting with [ValidateNotNullorEmpty]"},"content":{"rendered":"

I've been writing about the different parameter validation attributes that you can use in your PowerShell scripting. One that I use in practically every script is [ValidateNotNullorEmpty()]. This validation will ensure that something is passed as a parameter value. I'm not talking about making a parameter mandatory; only that if the user decides to use the parameter that something is passed. Let's look at my demo.<\/p>\n


\n#requires -version 2.0<\/p>\n

Param (
\n[Parameter(Position=0,Mandatory=$True,HelpMessage=\"Enter a process name like lsass\")]
\n[ValidateNotNullorEmpty()]
\n[string]$Name,
\n[Parameter(Position=1)]
\n[ValidateNotNullorEmpty()]
\n[string]$Computername=$env:computername<\/p>\n

)<\/p>\n

Try {
\n Get-Process -Name $name -ComputerName $computername -errorAction \"Stop\" | Select *,
\n @{Name=\"Runtime\";Expression={(Get-Date)-$_.StartTime}}
\n}<\/p>\n

Catch {
\n Write-Warning $_.Exception.Message
\n}
\n<\/code><\/p>\n

I've used the attribute on both parameters. The first parameter I've also made mandatory which makes it more likely that something will be entered. But if not, then the script will fail.<\/p>\n

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

I would get a similar message if the user forgot to complete the command.<\/p>\n

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

Even though I'm using a default value for Computername, as soon as the parameter is detected PowerShell assumes I'm going to use a different value.<\/p>\n

Validation should work for missing values, a variable that might be null, or in general anything that is meaningless. However, it won't prevent something quirky like this:<\/p>\n


\nPS S:\\> $p=\" \"
\nPS S:\\> .\\demo-ValidateNotNull.ps1 -name $p
\nWARNING: Cannot find a process with the name \" \". Verify the process name and
\ncall the cmdlet again.
\n<\/code><\/p>\n

The variable, while semantically meaningless to us, is not null or empty but a string of 1 space. If there's the chance you might run into this situation then you can add additional validation checks to the parameter.<\/p>\n

If you'd like, feel free to download Demo-ValidateNotNull<\/a> and see for yourself.<\/p>\n","protected":false},"excerpt":{"rendered":"

I’ve been writing about the different parameter validation attributes that you can use in your PowerShell scripting. One that I use in practically every script is [ValidateNotNullorEmpty()]. This validation will ensure that something is passed as a parameter value. I’m not talking about making a parameter mandatory; only that if the user decides to use…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[75,8],"tags":[534,540,372],"class_list":["post-2306","post","type-post","status-publish","format-standard","hentry","category-powershell-v2-0","category-scripting","tag-powershell","tag-scripting","tag-validation"],"yoast_head":"\nPowerShell Scripting with [ValidateNotNullorEmpty] • The Lonely Administrator<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jdhitsolutions.com\/blog\/scripting\/2306\/powershell-scripting-with-validatenotnullorempty\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"PowerShell Scripting with [ValidateNotNullorEmpty] • The Lonely Administrator\" \/>\n<meta property=\"og:description\" content=\"I've been writing about the different parameter validation attributes that you can use in your PowerShell scripting. 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[ValidateRange]","author":"Jeffery Hicks","date":"April 11, 2012","format":false,"excerpt":"After my post yesterday on using the ValidateScript attribute with PSCredentials, I thought you might find it helpful to have a brief discussion on some other parameter validation attributes such as [ValidateRange()]. You can use this attribute if you want to verify that a given parameter value falls between some\u2026","rel":"","context":"In "PowerShell"","block_context":{"text":"PowerShell","link":"https:\/\/jdhitsolutions.com\/blog\/category\/powershell\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2206,"url":"https:\/\/jdhitsolutions.com\/blog\/powershell\/2206\/powershell-scripting-with-validateset\/","url_meta":{"origin":2306,"position":1},"title":"PowerShell Scripting with [ValidateSet]","author":"Jeffery Hicks","date":"April 16, 2012","format":false,"excerpt":"Today we'll continue our exploration of the parameter validation attributes you can use in you PowerShell scripting. We've already looked at [ValidateRange] and [ValidateScript]. Another attribute you are likely to use is [ValidateSet()]. You can use this to verify that the parameter value belongs to a pre-defined set. To use,\u2026","rel":"","context":"In "PowerShell"","block_context":{"text":"PowerShell","link":"https:\/\/jdhitsolutions.com\/blog\/category\/powershell\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2182,"url":"https:\/\/jdhitsolutions.com\/blog\/powershell\/2182\/scripting-with-pscredential\/","url_meta":{"origin":2306,"position":2},"title":"Scripting with PSCredential","author":"Jeffery Hicks","date":"April 10, 2012","format":false,"excerpt":"I see this question often: how can I pass a parameter value for a PSCredential that might be a credential object or it might be a user name? In the past I've used code like this: begin { Write-Verbose -Message \"Starting $($myinvocation.mycommand)\" write-verbose -Message \"Using volume $($volume.toUpper())\" #convert credential to\u2026","rel":"","context":"In "PowerShell"","block_context":{"text":"PowerShell","link":"https:\/\/jdhitsolutions.com\/blog\/category\/powershell\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2247,"url":"https:\/\/jdhitsolutions.com\/blog\/scripting\/2247\/powershell-scripting-with-validatecount\/","url_meta":{"origin":2306,"position":3},"title":"PowerShell Scripting with [ValidateCount]","author":"Jeffery Hicks","date":"April 26, 2012","format":false,"excerpt":"Here's another parameter validation attribute you might want to use in your PowerShell scripting and functions. If your parameter can take an array of values, you might want to limit that array to a certain size. For example, your parameter can take an array of computer names but you don't\u2026","rel":"","context":"In "PowerShell v2.0"","block_context":{"text":"PowerShell v2.0","link":"https:\/\/jdhitsolutions.com\/blog\/category\/powershell-v2-0\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/jdhitsolutions.com\/blog\/wp-content\/uploads\/2012\/04\/validatecount-ok-300x66.png?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2219,"url":"https:\/\/jdhitsolutions.com\/blog\/powershell\/2219\/powershell-scripting-with-validatelength\/","url_meta":{"origin":2306,"position":4},"title":"PowerShell Scripting with [ValidateLength]","author":"Jeffery Hicks","date":"April 20, 2012","format":false,"excerpt":"In continuing the exploration of parameter validation attributes, today we'll look at [ValidateLength()]. You can use this attribute in your PowerShell scripting to validate that a parameter value is at least a certain length and no more and a certain length. In other words, it has to be just right.\u2026","rel":"","context":"In "PowerShell"","block_context":{"text":"PowerShell","link":"https:\/\/jdhitsolutions.com\/blog\/category\/powershell\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/jdhitsolutions.com\/blog\/wp-content\/uploads\/2012\/04\/thisbig.png?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2752,"url":"https:\/\/jdhitsolutions.com\/blog\/powershell\/2752\/rename-hashtable-key-revised\/","url_meta":{"origin":2306,"position":5},"title":"Rename Hashtable Key Revised","author":"Jeffery Hicks","date":"January 24, 2013","format":false,"excerpt":"Last week I posted an advanced PowerShell function to rename a hashtable key. As usual, the more I worked with it the more I realized it was missing something - namely the ability the take a pipelined object. My original version assumed you had saved the hashtable to a variable.\u2026","rel":"","context":"In "PowerShell"","block_context":{"text":"PowerShell","link":"https:\/\/jdhitsolutions.com\/blog\/category\/powershell\/"},"img":{"alt_text":"rename-hashtable-paramsets","src":"https:\/\/i0.wp.com\/jdhitsolutions.com\/blog\/wp-content\/uploads\/2013\/01\/rename-hashtable-paramsets-1024x319.png?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/jdhitsolutions.com\/blog\/wp-content\/uploads\/2013\/01\/rename-hashtable-paramsets-1024x319.png?resize=350%2C200 1x, https:\/\/i0.wp.com\/jdhitsolutions.com\/blog\/wp-content\/uploads\/2013\/01\/rename-hashtable-paramsets-1024x319.png?resize=525%2C300 1.5x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/posts\/2306","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/comments?post=2306"}],"version-history":[{"count":0,"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/posts\/2306\/revisions"}],"wp:attachment":[{"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/media?parent=2306"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/categories?post=2306"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jdhitsolutions.com\/blog\/wp-json\/wp\/v2\/tags?post=2306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}