StevenTCramer / typescript-nuget-bug

GeneratePackageOnBuild with TypeScript bug

When using TypeScript and GeneratePackageOnBuild together causes the following on the second build:

Two assets found targeting the same path with incompatible asset kinds

Reproduce

Create Razor class library

First lets create a new Razor/Blazor class library.

dotnet new razorclasslib -n Bug

confirm it builds

cd .\Bug\
dotnet build

Enable pack on build

Open the csproj file and add the GeneratePackageOnBuild property inside of the PropertGroup:

<GeneratePackageOnBuild>true</GeneratePackageOnBuild>

dotnet build

Confirm NuGet creation

Open the generated NuGet using NuGet Package Explorer

confirm the staticwebassets are included in the NuGet

Add some TypeScript

Create a directory for our TypeScript files and navigate into it.

mkdir ts
Push-Location ts

Create hello.ts

New-item "hello.ts" -Value "console.log('Hello World');"
Pop-Location

Add TypeScript build tools

We need to be able to transpile the TypeScript to JavaScript and put it in the wwwroot folder. Lets add the tooling to do this.

dotnet add package Microsoft.TypeScript.MSBuild --version 4.8.4

Configure the TypeScript build output for the wwwroot folder by setting the TypescriptOutDir property inside of a PropertyGroup in the project file:

<TypescriptOutDir>wwwroot</TypescriptOutDir>

Include the TypeScript target as a dependency of the PrepareForBuildDependsOn target by adding the following target inside of a PropertyGroup in the project file:

<PrepareForBuildDependsOn>CompileTypeScript;GetTypeScriptOutputForPublishing;$(PrepareForBuildDependsOn)</PrepareForBuildDependsOn>

Now confirm that when we build the project it creates a hello.js file in the wwwroot folder.

dotnet build

Confirm the NuGet contains staticwebassets using NuGet Package Explorer.

The Error

Now run dotnet build again.

dotnet build

You will see the following error:

 Two assets found targeting the same path with incompatible asset kinds

Workaround

Set GeneratePackageOnBuild to false and ensure you do a dotnet clean prior to running dotnet pack.

References

Typescript integration (docs)
Add TypeScript support with NuGet (docs)
NuGet Package Explorer (MS Store)
Razor Class Library isn't adding typescript output to static web assets (Github issue)