ASP NET Core 2 找不到包“Projectname.Model”的编译库位置

在我的解决方案中，我有两个项目。其中之一是web项目，另一个是Model项目。您可以在下面看到我的解决方案结构：

现在，当我运行应用程序时，出现以下错误：

InvalidOperationException：找不到包“ContosoUniversity.Model”的编译库位置

这是完整的堆栈跟踪：

An unhandled exception occurred while processing the request.
InvalidOperationException: Cannot find compilation library location for package 'ContosoUniversity.Model'
Microsoft.Extensions.DependencyModel.CompilationLibrary.ResolveReferencePaths(ICompilationAssemblyResolver resolver, List<string> assemblies)
InvalidOperationException: Cannot find compilation library location for package 'ContosoUniversity.Model'
Microsoft.Extensions.DependencyModel.CompilationLibrary.ResolveReferencePaths(ICompilationAssemblyResolver resolver, List<string> assemblies)
Microsoft.Extensions.DependencyModel.CompilationLibrary.ResolveReferencePaths()
Microsoft.AspNetCore.Mvc.ApplicationParts.AssemblyPart+<>c.<GetReferencePaths>b__8_0(CompilationLibrary library)
System.Linq.Enumerable+SelectManySingleSelectorIterator.MoveNext()
Microsoft.AspNetCore.Mvc.Razor.Compilation.MetadataReferenceFeatureProvider.PopulateFeature(IEnumerable<ApplicationPart> parts, MetadataReferenceFeature feature)
Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPartManager.PopulateFeature<TFeature>(TFeature feature)
Microsoft.AspNetCore.Mvc.Razor.Internal.DefaultRazorReferenceManager.GetCompilationReferences()
System.Threading.LazyInitializer.EnsureInitializedCore<T>(ref T target, ref bool initialized, ref object syncLock, Func<T> valueFactory)
Microsoft.AspNetCore.Mvc.Razor.Internal.DefaultRazorReferenceManager.get_CompilationReferences()
Microsoft.AspNetCore.Mvc.Razor.Internal.LazyMetadataReferenceFeature.get_References()
Microsoft.CodeAnalysis.Razor.CompilationTagHelperFeature.GetDescriptors()
Microsoft.AspNetCore.Razor.Language.DefaultRazorTagHelperBinderPhase.ExecuteCore(RazorCodeDocument codeDocument)
Microsoft.AspNetCore.Razor.Language.RazorEnginePhaseBase.Execute(RazorCodeDocument codeDocument)
Microsoft.AspNetCore.Razor.Language.DefaultRazorEngine.Process(RazorCodeDocument document)
Microsoft.AspNetCore.Razor.Language.RazorTemplateEngine.GenerateCode(RazorCodeDocument codeDocument)
Microsoft.AspNetCore.Mvc.Razor.Internal.RazorViewCompiler.CompileAndEmit(string relativePath)
Microsoft.AspNetCore.Mvc.Razor.Internal.RazorViewCompiler.CreateCacheEntry(string normalizedPath) 
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
System.Runtime.CompilerServices.TaskAwaiter.GetResult()
Microsoft.AspNetCore.Mvc.Razor.Internal.DefaultRazorPageFactoryProvider.CreateFactory(string relativePath)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.CreateCacheResult(HashSet<IChangeToken> expirationTokens, string relativePath, bool isMainPage)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.OnCacheMiss(ViewLocationExpanderContext expanderContext, ViewLocationCacheKey cacheKey)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.LocatePageFromViewLocations(ActionContext actionContext, string pageName, bool isMainPage)
Microsoft.AspNetCore.Mvc.Razor.RazorViewEngine.FindView(ActionContext context, string viewName, bool isMainPage)
Microsoft.AspNetCore.Mvc.ViewEngines.CompositeViewEngine.FindView(ActionContext context, string viewName, bool isMainPage)
Microsoft.AspNetCore.Mvc.ViewFeatures.Internal.ViewResultExecutor.FindView(ActionContext actionContext, ViewResult viewResult)
Microsoft.AspNetCore.Mvc.ViewResult+<ExecuteResultAsync>d__26.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeResultAsync>d__19.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeNextResultFilterAsync>d__24.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResultExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeNextResourceFilter>d__22.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(ref State next, ref Scope scope, ref object state, ref bool isCompleted)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeFilterPipelineAsync>d__17.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker+<InvokeAsync>d__15.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Builder.RouterMiddleware+<Invoke>d__4.MoveNext()
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware+<Invoke>d__7.MoveNext()

我使用 ASP NET Core 2 和 VS17。

这是我的ContosoUniversity.csproj文件（如果需要）：

<Project Sdk="Microsoft.NET.Sdk.Web">

<PropertyGroup>
  <TargetFramework>netcoreapp2.0</TargetFramework>
</PropertyGroup>

<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.0" />
  <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.0.0" />
</ItemGroup>

<ItemGroup>
  <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" />
</ItemGroup>

<ItemGroup>
  <Reference Include="ContosoUniversity.Model">
    <HintPath>..\ContosoUniversity.Model\bin\Debug\netcoreapp2.0\ContosoUniversity.Model.dll</HintPath>
  </Reference>
</ItemGroup>

</Project>

我应该怎么做才能解决这个问题？

为了让asp.net core 2.0项目成功找到外部程序集.NETStandard2.0，您需要重写内置的MetadataReferenceFeatureProvider。为此，我们需要添加以下类：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection.PortableExecutable;
using Microsoft.AspNetCore.Mvc.ApplicationParts;
using Microsoft.CodeAnalysis;
using Microsoft.Extensions.DependencyModel;

namespace Microsoft.AspNetCore.Mvc.Razor.Compilation
{
    /// <summary>Провайдер нужен для компенсации бага компиляции представлений при подключении сборок .NetStandart2.0</summary>
    public class ReferencesMetadataReferenceFeatureProvider : IApplicationFeatureProvider<MetadataReferenceFeature>
    {
        public void PopulateFeature(IEnumerable<ApplicationPart> parts, MetadataReferenceFeature feature)
        {
            var libraryPaths = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            foreach (var assemblyPart in parts.OfType<AssemblyPart>())
            {
                var dependencyContext = DependencyContext.Load(assemblyPart.Assembly);
                if (dependencyContext != null)
                {
                    foreach (var library in dependencyContext.CompileLibraries)
                    {
                        if (string.Equals("reference", library.Type, StringComparison.OrdinalIgnoreCase))
                        {
                            foreach (var libraryAssembly in library.Assemblies)
                            {
                                libraryPaths.Add(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, libraryAssembly));
                            }
                        }
                        else
                        {
                            foreach (var path in library.ResolveReferencePaths())
                            {
                                libraryPaths.Add(path);
                            }
                        }
                    }
                }
                else
                {
                    libraryPaths.Add(assemblyPart.Assembly.Location);
                }
            }

            foreach (var path in libraryPaths)
            {
                feature.MetadataReferences.Add(CreateMetadataReference(path));
            }
        }

        private static MetadataReference CreateMetadataReference(string path)
        {
            using (var stream = File.OpenRead(path))
            {
                var moduleMetadata = ModuleMetadata.CreateFromStream(stream, PEStreamOptions.PrefetchMetadata);
                var assemblyMetadata = AssemblyMetadata.Create(moduleMetadata);

                return assemblyMetadata.GetReference(filePath: path);
            }
        }
    }
}

并且还将启动中的“services.AddMvc()”替换为以下代码：

services.AddMvc() // Следующий патч нужен для компенсации бага компиляции представлений при подключении сборок .NetStandart2.0
    .ConfigureApplicationPartManager(manager =>
    {
        manager.FeatureProviders.Remove(manager.FeatureProviders.First(f => f is MetadataReferenceFeatureProvider));
        manager.FeatureProviders.Add(new ReferencesMetadataReferenceFeatureProvider());
    });