diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellExperimentalClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellExperimentalClientCodegen.java
index 8581afb94138..889940429074 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellExperimentalClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PowerShellExperimentalClientCodegen.java
@@ -1019,4 +1019,9 @@ private String toMethodName(String operationId) {
         // not using powershell verb
         return "Invoke-" + apiNamePrefix + methodName;
     }
+
+    @Override
+    public String toRegularExpression(String pattern) {
+        return escapeText(pattern);
+    }
 }
diff --git a/modules/openapi-generator/src/main/resources/powershell-experimental/model.mustache b/modules/openapi-generator/src/main/resources/powershell-experimental/model.mustache
index c050cc30593c..81d5dba1324a 100644
--- a/modules/openapi-generator/src/main/resources/powershell-experimental/model.mustache
+++ b/modules/openapi-generator/src/main/resources/powershell-experimental/model.mustache
@@ -24,7 +24,15 @@ function Initialize-{{{apiNamePrefix}}}{{{classname}}} {
     [CmdletBinding()]
     Param (
 {{#allVars}}
-        [Parameter(Position = {{vendorExtensions.x-index}}, ValueFromPipelineByPropertyName = $true{{#required}}, Mandatory = $true{{/required}})]
+        [Parameter(Position = {{vendorExtensions.x-index}}, ValueFromPipelineByPropertyName = $true)]
+        {{#pattern}}
+        [ValidatePattern("{{{.}}}")]
+        {{/pattern}}
+        {{#isEnum}}
+        {{#allowableValues}}
+        [ValidateSet({{#values}}"{{{.}}}"{{^-last}}, {{/-last}}{{/values}})]
+        {{/allowableValues}}
+        {{/isEnum}}
         [{{vendorExtensions.x-powershell-data-type}}]
         {{=<% %>=}}
         ${<%name%>}<%^-last%>,<%/-last%>
@@ -36,6 +44,54 @@ function Initialize-{{{apiNamePrefix}}}{{{classname}}} {
         'Creating PSCustomObject: {{{packageName}}} => {{{apiNamePrefix}}}{{{classname}}}' | Write-Debug
         $PSBoundParameters | Out-DebugParameter | Write-Debug
 
+        {{#vars}}
+        {{^isNullable}}
+        {{#required}}
+        if (!${{{name}}}) {
+            throw "invalid value for '{{{name}}}', '{{{name}}}' cannot be null."
+        }
+
+        {{/required}}
+        {{/isNullable}}
+        {{#hasValidation}}
+        {{#maxLength}}
+        if ({{^required}}!${{{name}}} -and {{/required}}${{{name}}}.length -gt {{{maxLength}}}) {
+            throw "invalid value for '{{{name}}}', the character length must be smaller than or equal to {{{maxLength}}}."
+        }
+
+        {{/maxLength}}
+        {{#minLength}}
+        if ({{^required}}!${{{name}}} -and {{/required}}${{{name}}}.length -lt {{{minLength}}}) {
+            throw "invalid value for '{{{name}}}', the character length must be great than or equal to {{{minLength}}}."
+        }
+
+        {{/minLength}}
+        {{#maximum}}
+        if ({{^required}}!${{{name}}} -and {{/required}}${{{name}}} {{#exclusiveMaximum}}-ge{{/exclusiveMaximum}}{{^exclusiveMaximum}}-gt{{/exclusiveMaximum}} {{{maximum}}}) {
+          throw "invalid value for '{{{name}}}', must be smaller than {{^exclusiveMaximum}}or equal to {{/exclusiveMaximum}}{{{maximum}}}."
+        }
+
+        {{/maximum}}
+        {{#minimum}}
+        if ({{^required}}!${{{name}}} -and {{/required}}${{{name}}} {{#exclusiveMinimum}}-le{{/exclusiveMinimum}}{{^exclusiveMinimum}}-lt{{/exclusiveMinimum}} {{{minimum}}}) {
+          throw "invalid value for '{{{name}}}', must be greater than {{^exclusiveMinimum}}or equal to {{/exclusiveMinimum}}{{{minimum}}}."
+        }
+
+        {{/minimum}}
+        {{#maxItems}}
+        if ({{^required}}!${{{name}}} -and {{/required}}${{{name}}}.length -gt {{{maxItems}}}) {
+            throw "invalid value for '{{{name}}}', number of items must be less than or equal to {{{maxItems}}}."
+        }
+
+        {{/maxItems}}
+        {{#minItems}}
+        if ({{^required}}!${{{name}}} -and {{/required}}${{{name}}}.length -lt {{{minItems}}}) {
+            throw "invalid value for '{{{name}}}', number of items must be greater than or equal to {{{minItems}}}."
+        }
+
+        {{/minItems}}
+        {{/hasValidation}}
+        {{/vars}}
         $PSO = [PSCustomObject]@{
             {{=<< >>=}}
             <<#allVars>>
diff --git a/samples/client/petstore/powershell-experimental/Test1.ps1 b/samples/client/petstore/powershell-experimental/Test1.ps1
index 268665d81b1f..2c6ab8827ae0 100644
--- a/samples/client/petstore/powershell-experimental/Test1.ps1
+++ b/samples/client/petstore/powershell-experimental/Test1.ps1
@@ -29,33 +29,36 @@ try {
     #Write-Host $pet
     $Result = Add-PSPet -Pet $pet
     Set-PSConfigurationApiKey -Id "api_key" -ApiKey "zzZZZZZZZZZZZZZ"
-    $result = Get-PSPetById -petId $Id -Verbose #-testHeader "testing only" -testQuery "testing something here"
+    $Result2 = Get-PSPetById -petId ($Id + 10) -Verbose -WithHttpInfo #-testHeader "testing only" -testQuery "testing something here"
+    Write-Host $Result2.GetType()
 } catch {
-    Write-Host ("Exception occured when calling '': {0}" -f ($_.ErrorDetails | ConvertFrom-Json))
-    Write-Host ("Response headers: {0}" -f ($_.Exception.Response.Headers | ConvertTo-Json))
+    #Write-Host ("Exception occured when calling '': {0}" -f ($_.ErrorDetails | ConvertFrom-Json))
+    #Write-Host ("Response headers: {0}" -f ($_.Exception.Response.Headers | ConvertTo-Json))
 }
 
+Write-Host "Before exit $($Result2.GetType())"
+
 #$result | Write-Host
 
 #$result | Select-Object -Property "photoUrls" | ConvertTo-Json | Write-Host
 #Write-Host "result =" + $result.photoUrls
 
 
-$pet2 = Initialize-PSPet -Id 20129 -Name '2foo' -Category (
-    Initialize-PSCategory -Id 20129 -Name '2bar'
-) -PhotoUrls @(
-    'http://example.com/2foo',
-    'http://example.com/2bar'
-) -Tags (
-    Initialize-PSTag -Id 3 -Name 'baz'
-) -Status Available
-
-#Write-Host $pet
-$Result = Add-PSPet -Pet $pet2
-
-$Result = Find-PSPetsByTags 'baz'
-Write-Host $Result.GetType().Name
-Write-Host $Result
+#$pet2 = Initialize-PSPet -Id 20129 -Name '2foo' -Category (
+#    Initialize-PSCategory -Id 20129 -Name '2bar'
+#) -PhotoUrls @(
+#    'http://example.com/2foo',
+#    'http://example.com/2bar'
+#) -Tags (
+#    Initialize-PSTag -Id 3 -Name 'baz'
+#) -Status Available
+#
+##Write-Host $pet
+#$Result = Add-PSPet -Pet $pet2
+#
+#$Result = Find-PSPetsByTags 'baz'
+#Write-Host $Result.GetType().Name
+#Write-Host $Result
 
 #$Result = Invoke-PetApiUpdatePetWithForm -petId $Id -Name "PowerShell Update" -Status "Pending"
 
diff --git a/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Category.ps1 b/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Category.ps1
index 0229faf745a5..d1d49b9c1043 100644
--- a/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Category.ps1
+++ b/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Category.ps1
@@ -32,6 +32,7 @@ function Initialize-PSCategory {
         [System.Nullable[Int64]]
         ${Id},
         [Parameter(Position = 1, ValueFromPipelineByPropertyName = $true)]
+        [ValidatePattern("^[a-zA-Z0-9]+[a-zA-Z0-9\\.\\-_]*[a-zA-Z0-9]+$")]
         [String]
         ${Name}
     )
diff --git a/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Order.ps1 b/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Order.ps1
index 01712b11284e..fd102068e30c 100644
--- a/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Order.ps1
+++ b/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Order.ps1
@@ -53,6 +53,7 @@ function Initialize-PSOrder {
         [System.Nullable[System.DateTime]]
         ${ShipDate},
         [Parameter(Position = 4, ValueFromPipelineByPropertyName = $true)]
+        [ValidateSet("placed", "approved", "delivered")]
         [String]
         ${Status},
         [Parameter(Position = 5, ValueFromPipelineByPropertyName = $true)]
diff --git a/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Pet.ps1 b/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Pet.ps1
index 801e97cdef06..47f41cff7761 100644
--- a/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Pet.ps1
+++ b/samples/client/petstore/powershell-experimental/src/PSPetstore/Model/Pet.ps1
@@ -46,16 +46,17 @@ function Initialize-PSPet {
         [Parameter(Position = 1, ValueFromPipelineByPropertyName = $true)]
         [PSCustomObject]
         ${Category},
-        [Parameter(Position = 2, ValueFromPipelineByPropertyName = $true, Mandatory = $true)]
+        [Parameter(Position = 2, ValueFromPipelineByPropertyName = $true)]
         [String]
         ${Name},
-        [Parameter(Position = 3, ValueFromPipelineByPropertyName = $true, Mandatory = $true)]
+        [Parameter(Position = 3, ValueFromPipelineByPropertyName = $true)]
         [String[]]
         ${PhotoUrls},
         [Parameter(Position = 4, ValueFromPipelineByPropertyName = $true)]
         [PSCustomObject[]]
         ${Tags},
         [Parameter(Position = 5, ValueFromPipelineByPropertyName = $true)]
+        [ValidateSet("available", "pending", "sold")]
         [String]
         ${Status}
     )
@@ -64,6 +65,14 @@ function Initialize-PSPet {
         'Creating PSCustomObject: PSPetstore => PSPet' | Write-Debug
         $PSBoundParameters | Out-DebugParameter | Write-Debug
 
+        if (!$Name) {
+            throw "invalid value for 'Name', 'Name' cannot be null."
+        }
+
+        if (!$PhotoUrls) {
+            throw "invalid value for 'PhotoUrls', 'PhotoUrls' cannot be null."
+        }
+
         $PSO = [PSCustomObject]@{
             "id" = ${Id}
             "category" = ${Category}