[Blazor] libman libraries not included in first build

Start with the referenced Microsoft.NET.Sdk.Publish.ComputeFiles.targets target and compare it with the Blazor MAUI build using the provided binlogs. Reproduce with the csproj, libman.json, and index.html steps, then verify that a clean first build includes the generated library files without requiring a second build.

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Issue moved from dotnet/maui#6709

• Please respond to @campersau.

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From @campersau on Saturday, April 30, 2022 6:31:24 PM

Description

Adding some client javascript libraries via libman does not include them in the first build.
When comparing the binlog with a blazor wasm build I can see that there is a _IncludePrePublishGeneratedContent target which is not present in the blazor maui build and thus any files which are generated under the wwwroot folder during the build are missing.

Here are the binlogs:
blazorbinlogs.zip

I only tested windows.

Steps to Reproduce

1. New Blazor Maui App
2. Add <PackageReference Include="Microsoft.Web.LibraryManager.Build" Version="2.1.161" PrivateAssets="all" /> to the csproj
3. Add libman.json with the following content:

{
  "version": "1.0",
  "defaultProvider": "cdnjs",
  "libraries": [
    {
      "library": "twitter-bootstrap@5.1.3",
      "files": [
        "css/bootstrap.min.css"
      ],
      "destination": "wwwroot/libs/bootstrap"
    }
  ]
}

4. Update index.html and reference <link rel="stylesheet" href="libs/bootstrap/css/bootstrap.min.css" /> instead.
5. Remove the wwwroot/libs folder and do a new build / run. This will add the libs folder back but the app does include the CSS file. If you run the app again without removing the wwwroot/libs folder the CSS is included correctly.

It would be great if the libman library files were included directly in the first build.

Alternatively you can clone https://github.com/campersau/blazor-maui-libmanbug and do step 5.

Version with bug

Release Candidate 2 (current)

Last version that worked well

Unknown/Other

Affected platforms

Windows

Affected platform versions

net6.0-windows10.0.19041.0

Did you find any workaround?

Building the project a second time works correctly as the libraries are already restored.

Or copy the msbuild target from https://github.com/dotnet/sdk/blob/c53c8ac81e1bcb8118c31bc4f5622396c72e9959/src/WebSdk/Publish/Targets/ComputeTargets/Microsoft.NET.Sdk.Publish.ComputeFiles.targets#L48-L60 into the csproj.

<Target Name="_IncludePrePublishGeneratedContent" BeforeTargets="GetCopyToPublishDirectoryItems" Condition=" '$(EnableDefaultItems)' == 'true' And '$(EnableDefaultContentItems)' == 'true' ">
    <ItemGroup>
        <!-- First, clean up previously generated content that may have been removed. -->
        <ContentWithTargetPath Remove="@(ContentWithTargetPath)" Condition="!Exists('%(Identity)')" />
        <!-- Next, include any newly generated content. -->
        <_WebProjectGeneratedContent Include="wwwroot\**" Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder);@(_ContentIncludedByDefault)" />
        <ContentWithTargetPath Include="@(_WebProjectGeneratedContent)" TargetPath="%(Identity)" CopyToPublishDirectory="PreserveNewest" />
    </ItemGroup>
</Target>

Relevant log output

No response