Powershell 101

Goal

Create a GitHub issue viewer that fetches the issues in the OctopusDeploy/Issues repository.

Requirements:

• Create a function Get-Issues that returns an array of issues.
• The returned issues should contain these fields: Number, Title, Labels, State, Created, Updated and Closed.
• Use the GitHub issues API for retrieving the issues.
• The API is paginated. The issue viewer should show the first n pages of results, where n is controlled by a parameter MaxPages (default to 3). That is, Get-Issues -MaxPages 5 should get the first 5 pages.
• Once the issue viewer is working, use it in powershell to:
  1. Display all fetched issues in tables, with Number and Title as the columns;
  2. Display all opening issues, sorted by the issue number in ascending order;
  3. Display all closed issues in descending order of the close time;
  4. Display all closed issues in descending order of the time taken to close that issue.
  5. For all issues that has a team/xxx label, show which team it is triaged to.

Completed Code

[Spoiler Alert] IssueViewer.ps1*

*Only visible in the solutions branch

Recap

• Cmdlets
  • Cmdlets are a key element of Powershell.
  • The name of cmdlets follows the convention of Verb-Noun.
  • A cmdlet performs an action and possibly returns an object.
  • We can pass the returned object to the next cmdlet using the | operator.
  • Use Get-Command to list all available cmdlets.
  • Use Get-Help to show the documentation for a cmdlet.
  • Use Get-Member to inspect the structure of a returned object.
• Syntax
  • Powershell has a similar syntax with most other languages, with some nuances.
  • Use keyword function to declare a function.
  • Use param ( ) block with [CmdletBinding()] attribute to create functions that can be invoked as cmdlets.
  • Use @( ) to declare an array.
  • Use @{ } to declare a dictionary.
  • Use -eq, -lt, -gt and so on instead of =, < and > operators.
• Common Cmdlets
  • Use Invoke-WebRequest to send http requests.
  • Use ConvertFrom-Json to parse a JSON string to a PSObject.
  • Use ForEach-Object to iterate through an array.
  • Use Where-Object to filter an array.
  • Use Select-Object to map one array to another.
  • Use Sort-Object to sort an array.

Challanges

1. Extend the cmdlet to take a parameter Repo, so it can work with other repositories.
2. Currently we need to run the .ps1 file to invoke the Get-Issues cmdlet. Change the code to a Powershell module and make it automatically loaded when Powershell starts, so that we can call this cmdlet in the same way as the built-in ones. hint
3. Add a parameter AllPages of the type switch. When it is present, fetch issues in all pages. hint
4. Display a progress bar when fetching the pages, showing the user how many pages have been completed. hint
5. Persist the results in a local file, and use it as a cache. hint
6. Support searching. hint
7. Add authentication mechanism so it can work with private repos. hint