Deduce the current attribute on ServiceNavigationNavItemTagHelper

Author: gunndabad

CHANGELOG.md

@@ -21,6 +21,9 @@ See [the SASS sample](samples/Samples.Sass) for an example of how to use this.
 #### `<govuk-service-navigation-nav>` tag helper
 A `collapse-navigation-on-mobile` attribute has been added to control whether the service navigation is collapsed on mobile devices.
 
+#### `<govuk-service-navigation-nav-item>` tag helper
+If not specified, the `current` attribute will be deduced by comparing the `href` attribute to the current request path.
+
 ## 3.1.2
 
 ### Fixes

docs/components/service-navigation.md

@@ -67,7 +67,7 @@ Must be inside a `<govuk-service-navigation-nav>` element.
 | Attribute | Type | Description |
 | --- | --- | --- |
 | `active` | `bool?` | Whether the user is within this group of pages in the navigation hierarchy. |
-| `current` | `bool?` | Whether the user is currently on this page. This takes precedence over the `active` attribute. |
+| `current` | `bool?` | Whether the user is currently on this page. This takes precedence over the `active` attribute. By default, this is determined by comparing the current URL to this item's generated `href` attribute. |
 | (link attributes) |  | See [documentation on links](../links.md) for more information. |
 
 

src/GovUk.Frontend.AspNetCore.Docs/GovUk.Frontend.AspNetCore.xml

@@ -1,8 +1,10 @@
+using System.ComponentModel;
 using System.Reflection;
 using System.Text;
 using System.Text.RegularExpressions;
 using System.Xml.Linq;
 using GovUk.Frontend.AspNetCore.TagHelpers;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 
 namespace GovUk.Frontend.AspNetCore.Docs;
@@ -57,10 +59,26 @@ public TagHelperApi GetTagHelperApi(string tagHelperName)
                 var memberName = m.Attribute("name")!.Value[(tagHelperClassName.Length + 3)..];
                 var member = tagHelperType.GetProperty(memberName)!;
 
+                if (member.GetCustomAttribute<ViewContextAttribute>() is not null)
+                {
+                    return null!;
+                }
+
+                if (member.GetCustomAttribute<ObsoleteAttribute>() is not null)
+                {
+                    return null!;
+                }
+
+                if (member.GetCustomAttribute<EditorBrowsableAttribute>() is { State: EditorBrowsableState.Never })
+                {
+                    return null!;
+                }
+
                 var typeName = GetNormalizedTypeName(member.PropertyType);
 
                 var htmlAttributeName = member.GetCustomAttribute<HtmlAttributeNameAttribute>()!;
                 var attributeName = htmlAttributeName.Name;
+
                 if (attributeName is null)
                 {
                     attributeName = htmlAttributeName.DictionaryAttributePrefix + "*";
@@ -76,7 +94,8 @@ public TagHelperApi GetTagHelperApi(string tagHelperName)
 
                 return new TagHelperApiAttribute(attributeName, typeName, description);
             })
-            .OrderBy(m => m.Name)
+            .Where(m => m is not null)
+            .OrderBy(m => m!.Name)
             .ToList();
 
         var canGenerateLinks = _anchorTagHelper.GetCustomAttributes<HtmlTargetElementAttribute>().Any(e => e.Tag == tagName);

src/GovUk.Frontend.AspNetCore.Docs/TagHelperApiProvider.cs

@@ -25,7 +25,7 @@ public class PaginationItemTagHelper : TagHelper
     /// Whether this item is the current page the user is on.
     /// </summary>
     /// <remarks>
-    /// By default this is determined by comparing the current URL to this item's generated <c>href</c> attribute.
+    /// By default, this is determined by comparing the current URL to this item's generated <c>href</c> attribute.
     /// </remarks>
     [HtmlAttributeName(CurrentAttributeName)]
     public bool? Current { get; set; }
@@ -34,9 +34,10 @@ public class PaginationItemTagHelper : TagHelper
     /// Whether this item is the current page the user is on.
     /// </summary>
     /// <remarks>
-    /// By default this is determined by comparing the current URL to this item's generated <c>href</c> attribute.
+    /// By default, this is determined by comparing the current URL to this item's generated <c>href</c> attribute.
     /// </remarks>
     [EditorBrowsable(EditorBrowsableState.Never)]
+    [HtmlAttributeName("is-current")]
     [Obsolete("Use the 'current' attribute instead.", DiagnosticId = DiagnosticIds.UseCurrentAttributeInstead)]
     public bool? IsCurrent
     {

src/GovUk.Frontend.AspNetCore/TagHelpers/PaginationItemTagHelper.cs

@@ -1,4 +1,9 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Text.Encodings.Web;
 using GovUk.Frontend.AspNetCore.ComponentGeneration;
+using Microsoft.AspNetCore.Http.Extensions;
+using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Razor.TagHelpers;
 
 namespace GovUk.Frontend.AspNetCore.TagHelpers;
@@ -30,10 +35,19 @@ public class ServiceNavigationNavItemTagHelper : TagHelper
     /// </summary>
     /// <remarks>
     /// This takes precedence over the <c>active</c> attribute.
+    /// By default, this is determined by comparing the current URL to this item's generated <c>href</c> attribute.
     /// </remarks>
     [HtmlAttributeName(CurrentAttributeName)]
     public bool? Current { get; set; }
 
+    /// <summary>
+    /// Gets the <see cref="ViewContext"/> of the executing view.
+    /// </summary>
+    [HtmlAttributeNotBound]
+    [ViewContext]
+    [DisallowNull]
+    public ViewContext? ViewContext { get; set; }
+
     /// <inheritdoc/>
     public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
     {
@@ -55,9 +69,11 @@ public override async Task ProcessAsync(TagHelperContext context, TagHelperOutpu
         attributes.Remove("href", out _);
         var href = output.GetUrlAttribute("href");
 
+        var current = Current ?? ItemIsCurrentPage();
+
         var item = new ServiceNavigationOptionsNavigationItem()
         {
-            Current = Current,
+            Current = current,
             Active = Active,
             Html = content.ToTemplateString(),
             Text = null,
@@ -73,5 +89,11 @@ public override async Task ProcessAsync(TagHelperContext context, TagHelperOutpu
         navContext.Items.Add(item);
 
         output.SuppressOutput();
+
+        bool ItemIsCurrentPage()
+        {
+            var currentUrl = ViewContext!.HttpContext.Request.GetEncodedPathAndQuery();
+            return href?.ToHtmlString(HtmlEncoder.Default) == currentUrl;
+        }
     }
 }