Merge pull request #180 from DFE-Digital/kebab-case-urls

Switch URLs from CamelCase to kebab-case

src/ServiceAssessmentService/ServiceAssessmentService.WebApp/Program.cs

@@ -7,6 +7,8 @@
 using ServiceAssessmentService.Application.Database;
 using ServiceAssessmentService.Application.UseCases;
 using ServiceAssessmentService.WebApp.Models;
+using Microsoft.AspNetCore.Mvc.ApplicationModels;
+using ServiceAssessmentService.WebApp;
 
 
 var builder = WebApplication.CreateBuilder(args);
@@ -26,7 +28,13 @@
     // By default, all incoming requests will be authorized according to the default policy.
     options.FallbackPolicy = options.DefaultPolicy;
 });
-builder.Services.AddRazorPages()
+
+builder.Services.AddRazorPages(options =>
+    {
+        // Convert CamelCase to kebab-case for page routes
+        // See also: https://www.gov.uk/guidance/content-design/url-standards-for-gov-uk
+        options.Conventions.Add(new PageRouteTransformerConvention(new SlugifyParameterTransformer()));
+    })
     .AddMicrosoftIdentityUI();
 
 // // Used for local accounts

src/ServiceAssessmentService/ServiceAssessmentService.WebApp/SlugifyParameterTransformer.cs

@@ -0,0 +1,33 @@
+using System.Text.RegularExpressions;
+
+namespace ServiceAssessmentService.WebApp;
+
+/// <summary>
+/// This class is used to transform the URL parameters to lowercase and replace spaces with hyphens.
+///
+/// See also the GDS guidance on URL, which requires lowercase and dash-separated words
+/// https://www.gov.uk/guidance/content-design/url-standards-for-gov-uk
+/// 
+/// For example:
+/// <code>
+///     /AssessmentRequest/Details/1
+///     vs 
+///     /assessment-request/details/1
+/// </code>
+///
+/// Implementation is based on the following article:
+/// https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-8.0#use-a-parameter-transformer-to-customize-token-replacement
+/// </summary>
+public class SlugifyParameterTransformer : IOutboundParameterTransformer
+{
+    public string? TransformOutbound(object? value)
+    {
+        if (value == null) { return null; }
+
+        return Regex.Replace(value.ToString()!,
+            "([a-z])([A-Z])",
+            "$1-$2",
+            RegexOptions.CultureInvariant,
+            TimeSpan.FromMilliseconds(100)).ToLowerInvariant();
+    }
+}