Check for a hashtable key before reading it.
PowerShell: ContainsKey distinguishes a missing key from a key whose value happens to be null.
$ErrorActionPreference = 'Stop'
Set-StrictMode -Version Latest
$settings = @{ theme='dark' }
$settings.ContainsKey('theme')
$settings.ContainsKey('port')Expected output EXAMPLE
True False
Details
Requires PowerShell 7. Save as snippet.ps1 and run pwsh -NoProfile -File snippet.ps1. Tested on Linux; these examples use portable paths and cmdlets. ContainsKey distinguishes a missing key from a key whose value happens to be null.
Tested on Ubuntu 24.04.5 LTS · · PowerShell 7.6.6 · powershell 7.6.6-1.deb
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Snippet process uid 65534 with a read-only root filesystem and temporary working files. Networking disabled. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged process) / C.UTF-8
- Interpreter invocation
pwsh -NoLogo -NoProfile -NonInteractive -File snippet.ps1- Container image ID
sha256:ec91410a8f6ec3e985830b5e3a0560306d36f8c1c5ccd91a6699abe707123fa3- Code SHA-256
049f411f96875128ec06f9587ebf3ef78493a7714ab9e04b344c468275db50ec- Dependencies
- powershell 7.6.6-1.deb
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
True False
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.