MapStaticAssets and Minimal APIs not working as expected

[benjaminsampica]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I am having issues using .MapStaticAssets() with minimal apis that return RazorComponentResult<T>. The static assets are being returned as they did with .UseStaticFiles(), but all of the great features that are supposed to come with MapStaticAssets don't appear to be working as I expect.

Expected Behavior

I expect the cache busting and compression features to work. It appears that the ETag feature is working.

Steps To Reproduce

Here is a link to the GitHub repository where it has been reproduced.

Please just pull the app and run it and observe the networking tab.

Exceptions (if any)

No response

.NET Version

9.0.100

Anything else?

[charring]

Was hoping to find some news/updates on this issue

[ranzlee]

I use ASP.NET Minimal APIs, RazorComponents, and htmx. A beautiful and simple way to build reactive and dynamic web applications that are robust and rely tried and true core web technologies. I would love to be able to leverage MapStaticAssets instead of response compression middleware and a custom cache buster, but alas no-go. If this is a Blazor-only feature, please let us know. It is presented as any other middleware, so the expectation is that it just works. Thank you for any update on this, much appreciated!!!

[maartenvansambeek]

I have the same problem, but managed to find a workaround, so I can do the following:

var appWithAssets = app.MapStaticAssetsForMinimalApi();

appWithAssets.MapGet("/",  () => new RazorComponentResult<Landing>());

It uses this extension method (which creates a ResourceAssetCollection just like the ResourceCollectionResolver does it).

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.StaticAssets.Infrastructure;

namespace Microsoft.AspNetCore.Routing;

/// <summary>
/// Extensions for the <see cref="IEndpointRouteBuilder"/> that enable fingerprinted static assets on minimal API.
/// </summary>
public static class StaticAssetsEndpointRoutingExtensions
{
    /// <summary>
    /// Maps static files produced during the build as endpoints.
    /// </summary>
    /// <param name="endpoints">The <see cref="IEndpointRouteBuilder"/>.</param>
    /// <param name="staticAssetsManifestPath">The path to the static assets manifest file.</param>
    /// <remarks>
    /// The <paramref name="staticAssetsManifestPath"/> can be null to use the <see cref="IHostEnvironment.ApplicationName"/> to locate the manifest.
    /// As an alternative, a full path can be specified to the manifest file. If a relative path is used, we'll search for the file in the <see cref="AppContext.BaseDirectory"/>." />
    /// </remarks>
    /// <returns>
    /// A <see cref="RouteGroupBuilder"/> that enables static files for all endpoints that are added to it.
    /// </returns>
    public static RouteGroupBuilder MapStaticAssetsForMinimalApi(this IEndpointRouteBuilder endpoints, string? staticAssetsManifestPath = null)
    {
        endpoints.MapStaticAssets(staticAssetsManifestPath);

        var resources = new List<ResourceAsset>();

        foreach (var descriptor in StaticAssetsEndpointDataSourceHelper.ResolveStaticAssetDescriptors(endpoints, null))
        {
            string? label = null;
            string? integrity = null;

            if (descriptor.Selectors.Count != 0)
            {
                continue;
            }

            var foundProperties = 0;

            foreach (var property in descriptor.Properties)
            {
                if (property.Name.Equals("label", StringComparison.OrdinalIgnoreCase))
                {
                    label = property.Value;
                    foundProperties++;
                }
                else if (property.Name.Equals("integrity", StringComparison.OrdinalIgnoreCase))
                {
                    integrity = property.Value;
                    foundProperties++;
                }
            }

            if (label != null || integrity != null)
            {
                var properties = new ResourceAssetProperty[foundProperties];
                var index = 0;
                if (label != null)
                {
                    properties[index++] = new("label", label);
                }

                if (integrity != null)
                {
                    properties[index] = new("integrity", integrity);
                }

                resources.Add(new(descriptor.Route, properties));
            }
            else
            {
                resources.Add(new(descriptor.Route, null));
            }
        }

        resources.Sort((a, b) => string.Compare(a.Url, b.Url, StringComparison.Ordinal));

        return endpoints.MapGroup(string.Empty).WithMetadata(new ResourceAssetCollection(new ResourceAssetCollection(resources)));
    }
}

[javiercn]

In essence #58937 (comment) is correct.

The resource collection is only a feature available in Blazor and Razor Pages apps.

Minimal APIs doesn't know anything about Blazor or Assets, so that functionality is not available.

I've filed #63398 to consider providing a helper to achieve this in the future.

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