在CSharpCompilation .net Core中未获取名称空间/引用

如何解决在CSharpCompilation .net Core中未获取名称空间/引用

我有一个使用一些动态编译代码的项目，并且我正在从.net框架升级到.net core 3.1。

我无法获得包含newtonsoft.json.dll的简单测试用例，并得到错误消息“找不到类型或名称空间名称'Newtonsoft'。当我第一次尝试添加库时，我遇到了类似的问题，但是通过使用当前加载的程序集（Can't include Newtonsoft JSON in CSharpCodeProvider script）克服了它。使用“ Core”，我不会得到关于库的错误，但是它不知道类型，就像它没有被加载一样。>

我尝试使用项目库（注释掉）并直接指定它们，但是存在相同的问题。要重新创建，请制作一个名为“ TestScript”的新.netCore 3.1控制台应用程序，并安装nuget软件包“ Microsoft.CodeAnalysis.CSharp.Scripting” v 3.7.0，“ Newtonsoft.Json” v12.0.3，并使用以下代码。

using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Reflection;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using System.Diagnostics;
using Newtonsoft.Json.Linq;

namespace TestScript
{  
  class Program
  {
    public static void Example1()
    {
      var assemblyName = "UserScript";
      var code = @"namespace UserScript
                { 
                  using System;
                  using System.IO;
                  using System.Collections.Generic;
                  using Newtonsoft.Json.Linq;
                  public class RunScript
                  {
                    private const int x = 99;
                    public int Eval()
                    {
                      JObject j = new JObject();
                      return x; 
                    }
                  }
                }";

      SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
      var references = new List<MetadataReference>();
      //Load project libraries
      //var assemblies = AppDomain.CurrentDomain
      //                .GetAssemblies()
      //                .Where(a => !a.IsDynamic)
      //                .Select(a => a.Location);
      //foreach (var item in assemblies)
      //{
      //  if (!item.Contains("xunit"))
      //    references.Add(MetadataReference.CreateFromFile(item));
      //}

      //or specify the libraries to load.

      var coreDir = Directory.GetParent(typeof(Enumerable).GetTypeInfo().Assembly.Location);
      var exeDir = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName);
      references.Add(MetadataReference.CreateFromFile(typeof(Object).GetTypeInfo().Assembly.Location));
      references.Add(MetadataReference.CreateFromFile(typeof(Uri).GetTypeInfo().Assembly.Location));
      references.Add(MetadataReference.CreateFromFile(coreDir.FullName + Path.DirectorySeparatorChar + "mscorlib.dll"));
      references.Add(MetadataReference.CreateFromFile(coreDir.FullName + Path.DirectorySeparatorChar + "System.Runtime.dll"));
      if (File.Exists(exeDir + "\\Newtonsoft.Json.dll"))
        references.Add(MetadataReference.CreateFromFile(exeDir + "\\Newtonsoft.Json.dll"));
      else
        throw new Exception("Missing newtonsoft DLL");


      CSharpCompilation compilation = CSharpCompilation.Create(
          assemblyName,new[] { syntaxTree },new MetadataReference[]
          {
        MetadataReference.CreateFromFile(typeof(object).Assembly.Location)
          },new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

      using (var memoryStream = new MemoryStream())
      {
        var result = compilation.Emit(memoryStream);

        if (result.Success)
        {
          memoryStream.Seek(0,SeekOrigin.Begin);
          Assembly assembly = Assembly.Load(memoryStream.ToArray());

          Type testClassType = assembly.GetType("TestNamespace.TestClass");
          var addResult = (int)testClassType.GetMethod("Add").Invoke(null,new object[] { 3,4 });
          Console.WriteLine(addResult);
        }
        else
        {
          Console.WriteLine("Failed to compile");
          for (var i = 0; i < result.Diagnostics.Length; i++)
          {
            Console.WriteLine(result.Diagnostics[i].ToString());
          }
        }
      }
    }
    static void Main(string[] args)
    {
      JObject j = null; //to make sure newtonsoft is included if loading current projects libraries

      Example1();
    }
  }
}

解决方法

如果您不忘记使用已建立的references列表，则您的代码应该可以正常工作。

请参阅.NET Fiddle（link）上的测试代码-我在那里使用了AppDomain方法（您已注释掉其中一个）。

CSharpCompilation compilation = CSharpCompilation.Create(
    assemblyName,new[] { syntaxTree },references,//<-- you're missing this
    new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

此外，您的调用实际上并没有调用正确的类和方法，我想您会在克服编译问题后才发现的。

// Non-existent Type and Method...
Type testClassType = assembly.GetType("TestNamespace.TestClass");
var addResult = (int)testClassType.GetMethod("Add").Invoke(null,new object[] { 3,4 });

编辑：以下是完整的工作代码，以防提琴被删除：

public static void Main(string[] args)
{
    var j = new JObject(); // ensure assembly is available
    Example1();
}

public static void Example1()
{
    var assemblyName = "UserScript";
    var code = @"namespace UserScript { 
                  using Newtonsoft.Json;
                  public class RunScript {
                   public static string Eval() {
                    return JsonConvert.SerializeObject(new int[] {1,2,3,4});
                   }
                  }
                }";

    SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
    
    //Load project libraries
    var references = AppDomain.CurrentDomain
        .GetAssemblies()
        .Where(a => !a.IsDynamic)
        .Select(a => a.Location)
        .Where(s => !string.IsNullOrEmpty(s))
        .Where(s => !s.Contains("xunit"))
        .Select(s => MetadataReference.CreateFromFile(s))
        .ToList()
        ;

    CSharpCompilation compilation = CSharpCompilation.Create(
        assemblyName,//<-- you're missing this
        new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));

    using (var memoryStream = new MemoryStream())
    {
        var result = compilation.Emit(memoryStream);

        if (result.Success)
        {
            memoryStream.Seek(0,SeekOrigin.Begin);
            Assembly assembly = Assembly.Load(memoryStream.ToArray());

            var testClassType = assembly.GetType("UserScript.RunScript");
            var invokeResult = (string)testClassType.GetMethod("Eval").Invoke(null,null);
            Console.WriteLine(invokeResult);
        }
        else
        {
            Console.WriteLine("Failed to compile");
            foreach (var diag in result.Diagnostics)
                Console.WriteLine(diag);
        }
    }
}