pkgs.buildDotnetModule {
  pname = "Utils.csproj";
  version = "0.1";

  src = ../..;

  projectFile = "src/Utils/Utils.csproj";

  nugetDeps = ./deps.json;
  packNupkg = true;
}```

preInstallPhase = "dotnetPackFlags=-p:RuntimeIdentifier=$dotnetRuntimeIds";

That would be slightly less hacky.

preInstall = "dotnetPackFlags=-p:RuntimeIdentifier=$dotnetRuntimeIds";

That would be slightly less hacky.

preInstall = "dotnetPackFlags=-p:RuntimeIdentifier=$dotnetRuntimeIds";

That would be slightly less hacky. (*edited)

I suppose that should be treated identically to .sln. I don't know which takes precedence, but it probably doesn't matter here.

There's also .slnf. I'm not sure if those take precedence over .proj files.

https://learn.microsoft.com/en-us/visualstudio/msbuild/solution-filters?view=vs-2022

In the case where you're using the .slnx solution file format, supported in MSBuild 17.12 and later, the .slnx file takes priority over the .slnf file.

I guess I'll test a few things

Actually looks like dotnet 9+ no longer try to guess, and just give:

MSBUILD : error MSB1011: Specify which project or solution file to use because this folder contains more than one project or solution file.

dotnet 8 will prefer .sln, but not .slnf and doesn't understand .slnx

_dotnetIsSolution() {
  local -r projectFile="${1-}"
  [[ $projectFile == *.sln || \
       ! -f $projectFile && \
         -n $(find "${projectFile:-.}" -maxdepth 1 -name \*.sln -print -quit) ]]
}

This is all it does in the PR. It just wants to know if you're attempting to build a solution

let
  Application = import ../Application { pkgs = pkgs; };
  DataMatrixGenerator = import ../../utils/DataMatrixGenerator { pkgs = pkgs; };
  Infrastrcture = import ../Infrastructure { pkgs = pkgs; };
  WebUI = import ../WebUI { pkgs = pkgs; };
in
pkgs.buildDotnetModule {
  pname = "API.csproj";
  version = "0.1";

  src = ../..;

  projectFile = "src/API/API.csproj";

  buildInputs = \[
    Application
    DataMatrixGenerator
    Infrastrcture
    WebUI
  \];

  dotnetPackFlags = \[ "-p:RuntimeIdentifier=linux-x64" \];
  nugetDeps = ./deps.json;
  packNupkg = false;
}