Enumerating package folders for .Net Core project

[paveliak]

Hi

I need to enumerate all package folders for a project basing on the project.assets.json file. The purpose is to extract licensing information about all project dependencies.

I couldn't find schema definition for that file but looking at the typical contents there seems to be two options. Could you help me understanding which of them is the preferred one:

• Use project->restore->packagesPath property and combine it with project->restore->fallbackFolder

"project": {
      "packagesPath": "/Users/someuser/.nuget/packages/",
      "projectStyle": "PackageReference",
      "fallbackFolders": [
        "/Users/someuser/MyProject/.dotnet/sdk/NuGetFallbackFolder"
      ],

• Use packageFolders property

"packageFolders": {
    "/Users/someuser/.nuget/packages/": {},
    "/Users/soimuser/MyProject/.dotnet/sdk/NuGetFallbackFolder": {}
  },

Thank you,
Pavel

[zarenner]

@nkolev92 any chance you're able to answer this?

[nkolev92]

The NuGet.g.props defines these in an MSBuild property, NuGetPackageFolders.

For example looking in my NuGet.Client projects nuget.g.props, I see:

    <NuGetPackageFolders Condition=" '$(NuGetPackageFolders)' == '' ">C:\Users\nikolev\.nuget\packages\;C:\Program Files\dotnet\sdk\NuGetFallbackFolder</NuGetPackageFolders>

Does that help/answer the question?

[zarenner]

@nkolev92 Not quite - in our scenario, we're only able to parse the project.assets.json (we cannot parse MSBuild). To locate a package on disk, we're trying to determine if it's more appropriate to search:

1. In order, the folders specified by packageFolders
   or
2. In order, the folders specified by both project->packagesPath and project->fallbackFolders

For example, a potential answer might be "you shouldn't use packageFolders since it's an object and the keys aren't guaranteed to be ordered", or alternatively "using only packagesPath+fallbackFolders will miss X that packageFolders would have". Or perhaps they're equivalent and doesn't matter which we use - we haven't seen a case where they differ, hence the question.

In short, which does NuGet itself actually use to resolve the package location?

[nkolev92]

I think you need to do the 1st one.
I think that's what the SDK does. Basically the SDK uses:

sdk/src/Tasks/Microsoft.NET.Build.Tasks/ResolvePackageAssets.cs

Line 652 in 8288f55

_packageResolver = NuGetPackageResolver.CreateResolver(_lockFile);

which in turn uses https://github.com/dotnet/sdk/blob/8288f55cf35fb642bf2838bd11b6e17d884f019f/src/Tasks/Microsoft.NET.Build.Tasks/NuGetPackageResolver.cs.

The priority order that matter is global packages folder, then fallback folders.

[nkolev92]

How are you reading the assets file btw?

[paveliak]

Thank you @nkolev92. We use standard Ruby JSON parser to read it after restoring the projects with dotnet restore.

[dsplaisted]

If you were to look at the package folders on disk, you would typically be looking at all the packages that had been restored for all projects on that machine, rather than just the packages that the current project is using.