Add NavigationManager.GetUriWithHash() extension method #64615

Copilot · 2025-12-02T22:31:18Z

Add NavigationManager.GetUriWithHash() extension method

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You've included unit or integration tests for your change, where applicable.
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Add GetUriWithHash() to construct URIs with hash fragments relative to current location

Description

Relative hash URLs resolve against baseURI, not the document location. When using <base href="/subdir/">, a link like <a href="#section1"> navigates to /subdir/#section1 instead of the current page's hash.

API Addition:

namespace Microsoft.AspNetCore.Components;

public static class NavigationManagerExtensions
{
    public static string GetUriWithHash(this NavigationManager navigationManager, string? hash);
}

Behavior:

Appends hash to current URI, replacing any existing hash
Prepends # if not present in input
Removes hash when null or empty string passed
Preserves query string parameters

Implementation:

Uses string.Create with Span APIs for minimal allocations
Pre-calculates exact buffer length needed
Copies data directly into pre-allocated buffer

Usage:

@inject NavigationManager Nav

<a href="@Nav.GetUriWithHash("section1")">Go to section 1</a>

Fixes #53499

Original prompt

This section details on the original issue you should resolve

<issue_title>[Blazor] Add NavigationManager.GetUriWithHash()</issue_title>
<issue_description>## Background and Motivation

Relative hash URLs get resolved relative to the document's baseURI, just like other relative links. This is fine if the document's baseURI matches its location (as is the case when a <base> element is not used), but it makes things inconvenient when the baseURI and location don't match.

For example, the following works when no <base> element exists, but doesn't work if the <head> were to contain something like <base href="/subidr/">.
@page "/home"

<a href="#section-1">Go to section 1</a>
...
<h1 id="section-1">Section 1</h1>
A NavigationManager.GetUriWithHash() API could help mitigate this issue:
@page "/home"
@inject NavigationManager Nav

<a href="@(Nav.GetUriWithHash("section-1"))">Go to section 1</a>
...
<h1 id="section-1">Section 1</h1>
Proposed API
namespace Microsoft.AspNetCore.Components;

public static class NavigationManagerExtensions
{
+  public static string GetUriWithHash(this NavigationManager navigationManager, string? hash);
}
Usage Examples
@page "/home"
@inject NavigationManager Nav

<a href="@(Nav.GetUriWithHash("section-1"))">Go to section 1</a>
...
<h1 id="section-1">Section 1</h1>
Alternative Designs

None considered yet.

Risks

None.</issue_description>

Comments on the Issue (you are @copilot in this section)
@ Thanks for contacting us.
We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.</comment_new>

Fixes [Blazor] Add NavigationManager.GetUriWithHash() #53499

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dotnet-policy-service · 2025-12-02T22:31:35Z

Greetings! You've submitted a PR that modifies code that is shared with https://github.com/dotnet/runtime . Please make sure you synchronize this code with the changes in that repo!

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

Copilot

Pull request overview

This PR adds a new GetUriWithHash() extension method to NavigationManager to address a longstanding issue with hash fragment URLs in Blazor applications. When a <base> element is used in the HTML document, relative hash URLs resolve against the base URI rather than the current document location, making it difficult to create in-page navigation links. The new API solves this by constructing absolute URIs with hash fragments relative to the current location.

Key Changes:

Added NavigationManager.GetUriWithHash() extension method that adds, updates, or removes hash fragments from the current URI
Comprehensive XML documentation with usage examples
Full test coverage including edge cases for hash manipulation

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
`src/Components/Components/src/NavigationManagerExtensions.cs`	Implements the new `GetUriWithHash()` method with proper null checking, hash prepending logic, and URI manipulation
`src/Components/Components/test/NavigationManagerTest.cs`	Adds comprehensive test coverage for the new method including hash addition, replacement, removal, and null parameter handling
`src/Components/Components/src/PublicAPI.Unshipped.txt`	Documents the new public API surface for tracking purposes

javiercn · 2025-12-03T14:15:52Z

src/Components/Components/src/NavigationManagerExtensions.cs

+
+    /// <summary>
+    /// Returns a URI constructed from <see cref="NavigationManager.Uri"/> with a hash
+    /// added, updated, or removed.
+    /// </summary>
+    /// <param name="navigationManager">The <see cref="NavigationManager"/>.</param>
+    /// <param name="hash">The hash string. If empty or null, the hash will be removed from the URI.</param>
+    /// <returns>The URI with the specified hash.</returns>
+    /// <remarks>
+    /// <para>
+    /// If <paramref name="hash"/> does not start with <c>#</c>, then <c>#</c> will be prepended.
+    /// </para>
+    /// <para>
+    /// This method is useful when the document's <c>baseURI</c> differs from its location,
+    /// such as when a <c>&lt;base&gt;</c> element is used, since relative hash URLs are resolved
+    /// relative to the <c>baseURI</c>.
+    /// </para>
+    /// <example>
+    /// <code>
+    /// @inject NavigationManager Nav
+    /// &lt;a href="@Nav.GetUriWithHash("section1")"&gt;Go to section 1&lt;/a&gt;
+    /// </code>
+    /// </example>
+    /// </remarks>
+    public static string GetUriWithHash(this NavigationManager navigationManager, string? hash)
+    {
+        ArgumentNullException.ThrowIfNull(navigationManager);
+
+        var uri = navigationManager.Uri;
+        var hashStartIndex = uri.IndexOf('#');
+
+        // Get URI without the existing hash
+        var uriWithoutHash = hashStartIndex < 0 ? uri : uri.Substring(0, hashStartIndex);
+
+        if (string.IsNullOrEmpty(hash))
+        {
+            return uriWithoutHash;
+        }
+
+        // Ensure hash starts with '#'
+        if (hash[0] != '#')
+        {
+            return string.Concat(uriWithoutHash, "#", hash);
+        }
+
+        return string.Concat(uriWithoutHash, hash);
+    }


@copilot can you search on the docs and in other helpers on the repo how to do this with minimal allocations? (Using the Span APIs)

Refactored to use string.Create for minimal allocations (e49d709). The implementation now:

Pre-calculates the exact buffer length needed

Uses string.Create with the existing strings and length values

Copies data using Span APIs directly into the pre-allocated buffer

Only creates one string allocation for the result

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

ilonatommy · 2025-12-04T09:03:57Z

@javiercn, it happened again. Copilot is producing descriptions with random issue number next to "fixes" keyword. This one has nothing to do with 41773 (I won't be linking it to avoid confusion).

ilonatommy · 2025-12-04T09:34:15Z

src/Components/Components/test/NavigationManagerTest.cs

+    [InlineData("scheme://host/path?query=value#oldHash", "section1", "scheme://host/path?query=value#section1")]
+    [InlineData("scheme://host/path#oldHash", "newHash", "scheme://host/path#newHash")]
+    [InlineData("scheme://host/path#old", "#new", "scheme://host/path#new")]
+    public void GetUriWithHash_AddsOrReplacesHash(string baseUri, string hash, string expectedUri)


None of these tests really checks base uri different than root. In the issue we had an example of a case with <base href="/subdir/">, we should test it.

ilonatommy · 2025-12-04T09:47:57Z

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -1 +1,2 @@
 #nullable enable
+static Microsoft.AspNetCore.Components.NavigationManagerExtensions.GetUriWithHash(this Microsoft.AspNetCore.Components.NavigationManager! navigationManager, string? hash) -> string!


I don't see a point of hash being nullable.

name GetUriWithHash does not make sense then, we don't get uri with hash calling this method. You see code navigationManager.GetUriWithHash() and you expect some hash to be retuned by that method.

if we really want to cheat the system and get the uri without hash, we can pass String.Empty to that param

Initial plan

1e6cf9b

Copilot AI assigned Copilot and javiercn Dec 2, 2025

dotnet-policy-service bot added the Attention: Shared Code Modified label Dec 2, 2025

Copilot started work on behalf of javiercn December 2, 2025 22:31 View session

Add GetUriWithHash() extension method to NavigationManagerExtensions

9dc30b9

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add NavigationManager.GetUriWithHash() method~~ Add NavigationManager.GetUriWithHash() extension method Dec 2, 2025

Copilot finished work on behalf of javiercn December 2, 2025 22:45

Copilot AI requested a review from javiercn December 2, 2025 22:45

javiercn marked this pull request as ready for review December 3, 2025 11:16

javiercn requested a review from a team as a code owner December 3, 2025 11:16

Copilot AI review requested due to automatic review settings December 3, 2025 11:16

Copilot started reviewing on behalf of javiercn December 3, 2025 11:17 View session

Copilot finished reviewing on behalf of javiercn December 3, 2025 11:19

Copilot AI reviewed Dec 3, 2025

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javiercn reviewed Dec 3, 2025

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Copilot started work on behalf of javiercn December 3, 2025 14:16 View session

Optimize GetUriWithHash to use string.Create for minimal allocations

e49d709

Co-authored-by: javiercn <6995051+javiercn@users.noreply.github.com>

Copilot AI requested a review from javiercn December 3, 2025 14:25

Copilot finished work on behalf of javiercn December 3, 2025 14:26

javiercn added the area-blazor Includes: Blazor, Razor Components label Dec 3, 2025

build-analysis bot mentioned this pull request Dec 3, 2025

Known Build Error: error : Cannot create a file when that file already exists. #61178

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ilonatommy reviewed Dec 4, 2025

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Add NavigationManager.GetUriWithHash() extension method #64615

Add NavigationManager.GetUriWithHash() extension method #64615

Copilot AI commented Dec 2, 2025 •

edited by ilonatommy

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		@@ -1 +1,2 @@
		#nullable enable
		static Microsoft.AspNetCore.Components.NavigationManagerExtensions.GetUriWithHash(this Microsoft.AspNetCore.Components.NavigationManager! navigationManager, string? hash) -> string!

Add NavigationManager.GetUriWithHash() extension method #64615

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Add NavigationManager.GetUriWithHash() extension method

Description

Proposed API

Usage Examples

Alternative Designs

Risks

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Copilot AI commented Dec 2, 2025 •

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