Fingerprinting client-side assets using the old school hosted approach

[Vizual-Dev]

I am using the old school hosted WASM approach for a Blazor application.

After upgrading to .NET 10 I have implemented Fingerprint client-side static assets in standalone Blazor WebAssembly apps.

When running the project from Visual Studio I and viewing the page source in the browser, I can see the import map and the fingerprinted assets:

The documentation says, "In standalone Blazor WebAssembly apps during build/publish, the framework overrides placeholders in index.html with values computed during build to fingerprint static assets for client-side rendering.".

When I publish my application via the Demo.Server project the placeholders are not overridden. The index.html in the published wwwroot still contains the placeholders:

If I publish the Demo.Client project directly the placeholders are overriden.

Is it possible for me to build the Demo.Server but also replace the placeholders in Demo.Client?

I have created a minimal repo to demonstrate the problem: https://github.com/Vizual-Dev/ImportMapDemo

[MihuBot]

I'm a bot. Here is a possible related and/or duplicate issue (I may be wrong):

• OverrideHtmlAssetPlaceholders is not honored when building from Server project #121121

[aligin]

I've temporary resolved this issue in super hacky way (don't blame me please).

Place this to Server.csproj

BlazorWebKit - it's my project name, replace it with your own.

<Target Name="PublishBlazorWasmClient" AfterTargets="Publish">
    <MSBuild Projects="..\BlazorWebKit.Client\BlazorWebKit.Client.csproj"
             Targets="Publish"
             Properties="Configuration=$(Configuration);
                        RuntimeIdentifier=$(RuntimeIdentifier);
                        _IsPublishing=true;
                        OverrideHtmlAssetPlaceholders=true;
                        PublishDir=/tmp/blazor/client"/>

    <!-- Clean the server's wwwroot directory before copying new files -->
    <RemoveDir Directories="$(PublishDir)wwwroot" ContinueOnError="true" />

    <!-- Copy the client's published output (with replaced fingerprints) to server's wwwroot -->
    <ItemGroup>
      <ClientPublishedFiles Include="/tmp/blazor/client/wwwroot/**/*.*" />
    </ItemGroup>

    <Copy SourceFiles="@(ClientPublishedFiles)"
          DestinationFolder="$(PublishDir)wwwroot\%(RecursiveDir)"
          SkipUnchangedFiles="true" />
  </Target>

/tmp/blazor/client - cause of linux CI builder. I can't debug the structure of the client published directory on linux and decided to use hardcoded path (docker container with temp published files dies after building).

[maraf]

Thank you for contacting us. I'm looking for the fix.

The underlaying problem is when WebAssembly project is referenced by Server project, MSBuild calls into the referenced project several times. The instance of the project is recreated for each call and so the collection of @(_HtmlStaticWebAssets) is not shared between Build and Publish.