Add example for checking if something exists

Author: PaulStovell

examples/06-CheckExists/IIS.ps1

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+# -----------------------------------------------------------------------------
+# Setup
+# -----------------------------------------------------------------------------
+$here = Split-Path -Parent $MyInvocation.MyCommand.Path
+cd $here
+
+. ..\_Setup.IIS.ps1
+
+mkdir "C:\Sites\Website1" -ErrorAction SilentlyContinue
+
+$manager = Get-IISServerManager
+$manager.ApplicationPools.Add("My Pool")
+$manager.Sites.Add("Website1", "http", "*:8022:", "C:\Sites\Website1")
+$manager.Sites["Website1"].Applications.Add("/MyApp", "C:\Sites\MyApp")
+$manager.CommitChanges()
+
+# -----------------------------------------------------------------------------
+# Example
+# -----------------------------------------------------------------------------
+Import-Module IISAdministration
+
+$manager = Get-IISServerManager
+
+# The pattern here is to get the things you want, then check if they are null
+
+if ($manager.ApplicationPools["My Pool"] -eq $null) {
+    # Application pool does not exist, create it...
+    # ...
+}
+
+if ($manager.Sites["Website1"] -eq $null) {
+    # Site does not exist, create it...
+    # ...
+}
+
+if ($manager.Sites["Website1"].Applications["/MyApp"] -eq $null) {
+    # App/virtual directory does not exist, create it...
+    # ...
+}
+
+$manager.CommitChanges()
+
+# -----------------------------------------------------------------------------
+# Assert
+# -----------------------------------------------------------------------------
+if ($manager.ApplicationPools["My Pool"] -eq $null -or $manager.ApplicationPools["sdij18uc"] -ne $null) { Write-Error "Our logic is wrong" }
+if ($manager.Sites["Website1"] -eq $null -or $manager.Sites["isjdjdsoidj"] -ne $null) { Write-Error "Our logic is wrong" }
+if ($manager.Sites["Website1"].Applications["/MyApp"] -eq $null -or $manager.Sites["Website1"].Applications["/sdidsuidshdsh"] -ne $null) { Write-Error "Our logic is wrong" }
+
+# -----------------------------------------------------------------------------
+# Clean up
+# -----------------------------------------------------------------------------
+
+. ..\_Teardown.IIS.ps1
+
+Remove-IISSite -Name "Website1" -Confirm:$false
+
+$manager = Get-IISServerManager
+$manager.ApplicationPools["My Pool"].Delete()
+$manager.CommitChanges()

examples/06-CheckExists/README.md

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+### Check whether sites, virtual directories or application pools already exist
+
+You'll re-deploy your application to IIS many times over the course of a project, so you can't assume the script is being run for the first time. The examples below show a pattern for checking whether a site, application, or application pool already exists before making a change. 

examples/06-CheckExists/Web.ps1

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+# -----------------------------------------------------------------------------
+# Setup
+# -----------------------------------------------------------------------------
+$here = Split-Path -Parent $MyInvocation.MyCommand.Path
+cd $here
+
+. ..\_Setup.Web.ps1
+
+mkdir "C:\Sites\Website1" -ErrorAction SilentlyContinue
+mkdir "C:\Sites\MyApp" -ErrorAction SilentlyContinue
+
+New-Item -Path "IIS:\AppPools" -Name "My Pool" -Type AppPool
+New-Website -Name "Website1" -Port 80 -IPAddress "*" -HostHeader "" -PhysicalPath "C:\Sites\Website1"
+New-Item -Type Application -Path "IIS:\Sites\Website1\MyApp" -physicalPath "C:\Sites\MyApp"
+
+# -----------------------------------------------------------------------------
+# Example
+# -----------------------------------------------------------------------------
+
+Import-Module WebAdministration
+
+# The pattern here is to use Test-Path with the IIS:\ drive provider
+
+if ((Test-Path "IIS:\AppPools\My Pool") -eq $False) {
+    # Application pool does not exist, create it...
+    # ...
+}
+
+if ((Test-Path "IIS:\Sites\Website1") -eq $False) {
+    # Site does not exist, create it...
+    # ...
+}
+
+if ((Test-Path "IIS:\Sites\Website1\MyApp") -eq $False) {
+    # App/virtual directory does not exist, create it...
+    # ...
+}
+
+# -----------------------------------------------------------------------------
+# Assert
+# -----------------------------------------------------------------------------
+
+if ((Test-Path "IIS:\AppPools\My Pool") -eq $false -or (Test-Path "IIS:\AppPools\sijsijd") -ne $false) { Write-Error "Our logic is wrong" }
+if ((Test-Path "IIS:\Sites\Website1") -eq $false -or (Test-Path "IIS:\Sites\sdijdsijdd") -ne $false) { Write-Error "Our logic is wrong" }
+if ((Test-Path "IIS:\Sites\Website1\MyApp") -eq $false -or (Test-Path "IIS:\Sites\Website1\sdddsds") -ne $false) { Write-Error "Our logic is wrong" }
+
+# -----------------------------------------------------------------------------
+# Clean up
+# -----------------------------------------------------------------------------
+
+. ..\_Teardown.Web.ps1
+
+Remove-Item -Path "IIS:\Sites\Website1" -Recurse -Force
+Remove-Item -Path "IIS:\AppPools\My Pool" -Recurse -Force