Dot Net Core and Azure Storage: Could not load fil

问题:

I have a web API running on "netcoreapp1.0" which is using Azure Storage Client. Accessing blobs has no issue at all but when I try execute any operation with tables it throws me this error:

Exception thrown: 'Microsoft.WindowsAzure.Storage.StorageException' in System.Private.CoreLib.ni.dll

Additional information: Could not load file or assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. The system cannot find the file specified.

The specific line it happens looks like this:

if (await table.ExistsAsync())

Even removing this, whenever it hits a line where it would actually do a HTTP call to Azure it still results the same. I am importing "net46", and I have tried also importing in my project.json "net40", but no change.

The code above is living in "Cameo.Azure.Storage.Library". It is targeting netstandard1.6 and it is referencing "WindowsAzure.Storage": "7.2.0" and "NETStandard.Library": "1.6.0".

My project.json is below:

{
  "dependencies": {
    "Cameo.Azure.Storage.Library": "1.0.0-*",
    "Cameo.GeoLocation": "1.0.0-*",
    "LightInject": "4.0.11",
    "LightInject.Microsoft.DependencyInjection": "1.0.1",
    "LocationService.Domain": "1.0.0-*",
    "Microsoft.AspNetCore.Authentication.Cookies": "1.0.0",
    "Microsoft.AspNetCore.Authentication.JwtBearer": "1.0.0",
    "Microsoft.AspNetCore.Mvc": "1.0.0",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Logging": "1.0.0",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.Extensions.Logging.Debug": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
    "Microsoft.NETCore.App": {
      "version": "1.0.0",
      "type": "platform"
    },
    "Swashbuckle": "6.0.0-beta902"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final"
  },

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "net46",
        "net40"
      ]
    }
  },

  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true,
    "xmlDoc": true
  },

  "runtimeOptions": {
    "configProperties": {
      "System.GC.Server": true
    }
  },

  "publishOptions": {
    "include": [
      "wwwroot",
      "Views",
      "Areas/**/Views",
      "appsettings.json",
      "web.config"
    ]
  },

  "scripts": {
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  }
}

The librarie's project.json

{
  "version": "1.0.0-*",

  "dependencies": {
    "Cameo.Azure.Storage.Interface": "1.0.0-*",
    "LightInject": "4.0.11",
    "Microsoft.Extensions.Configuration": "1.0.0",
    "Microsoft.Extensions.Options": "1.0.0",
    "NETStandard.Library": "1.6.0",
    "WindowsAzure.Storage": "7.2.0"
  },

  "frameworks": {
    "netstandard1.6": {
      "imports": [
        "net46"
      ]
    }
  }
}

回答1:

You can't use .NET 4.0 or .NET 4.6 assemblies in .NET Core. You need either versions that support .NET Core (if there are any) or target .NET Core.

What you did in the following section is only to circumvent NuGet target check

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "net46",
        "net40"
      ]
    }
  },

But this will not magically make the .NET 4.x libraries work with .NET Core. .NET Core library need to target netstandard1.x or netcoreapp1.0 (there are are also some - but not all - Portable Class Libraries that were designed for Windows Phone 8, 8.1 or 10 that may work, but depends on the specific library) in order to run with .NET Core.

On top of that, you are even referencing an library for ASP.NET MVC 5 in your project, which is for sure not going to work as there is no System.Web.* anymore in .NET Core (its tightly coupled to IIS).

You will need the WindowsAzure.Storage package from Microsoft in the version 7.2, which supports .NET Core and can be found on NuGet here.

回答2:

Changing the project.json in web API to this has solved the issue.

"frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "portable-net45+win8"
      ]
    }
  }

You can only import core or portable (PCL) version of the framework. Reference:

https://blogs.msdn.microsoft.com/cesardelatorre/2016/06/28/running-net-core-apps-on-multiple-frameworks-and-what-the-target-framework-monikers-tfms-are-about/

It is important to use “imports” only for versions of .NET Core and PCL (Portable Class Libraries). Using it with TFMS from the traditional .NET Framework can cause issues or malfunction.