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我有一个无法解决的奇怪问题。我大部分时间都在成功编译动态程序集，但在编译以下行时遇到了一个奇怪的问题：

返回新的 JObject().Properties().ElementAt(0).Value();

出现错误：

System.ApplicationException: 'Error creating dynamic code assembly 'IEnumerable<JProperty>' does not contain a definition for 'ElementAt' and no accessible extension method 'ElementAt' accepting a first argument of type 'IEnumerable<JProperty>' could be found (are you missing a using directive or an assembly reference?) '

当在项目中创建为真实类时，发出的文本输出可以正常工作，但在动态程序集中则不行。该项目是一个 asp.net core 2.2 项目，它引用了一个创建动态程序集的程序集。

这是创建程序集的代码：

public static class Class2
{
    public static Assembly GenerateAssenbly()
    {

        //generate the code
        StringBuilder sb = new StringBuilder("");
        sb.AppendLine("using System;");
        sb.AppendLine("using System.Linq;");

        sb.AppendLine("using Newtonsoft.Json;");
        sb.AppendLine("using Newtonsoft.Json.Linq;");

        sb.AppendLine("namespace test");
        sb.AppendLine("{");
        sb.AppendLine($"class Parser");
        sb.AppendLine("{");

        sb.AppendLine($"public object test() ");
        sb.AppendLine("{");
        sb.AppendLine("return new JObject().Properties().ElementAt(0).Value<string>();");
        sb.AppendLine("}");

        sb.AppendLine("}"); //class
        sb.AppendLine("}"); //namespace

        SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(sb.ToString());

        var runtimeAssemblyDirectory = Path.GetDirectoryName(typeof(object).Assembly.Location);
        string assemblyName = Path.GetRandomFileName();
        MetadataReference[] references = new MetadataReference[]
        {
            MetadataReference.CreateFromFile(typeof(object).GetTypeInfo().Assembly.Location),
            MetadataReference.CreateFromFile(Assembly.GetExecutingAssembly().Location),
            MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "System.Runtime.dll")),
            MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "mscorlib.dll")),
            MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "System.dll")),
            MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "netstandard.dll")),
            MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "System.Core.dll")),

            MetadataReference.CreateFromFile(typeof(JObject).GetTypeInfo().Assembly.Location),
        };

        CSharpCompilation compilation = CSharpCompilation.Create(
            assemblyName,
            syntaxTrees: new[] { syntaxTree },
            references: references,
            options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));


        Debug.Print(sb.ToString()); // copy output to a class to test

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

            if (!result.Success)
            {
                throw new ApplicationException($"Error creating dynamic code assembly " + GetCompilerResultsErrors(result));
            }
            else
            {
                return Assembly.Load(ms.GetBuffer());
            }
        }
    }

    private static string GetCompilerResultsErrors(EmitResult result)
    {
        StringBuilder sb = new StringBuilder();

        IEnumerable<Diagnostic> failures = result.Diagnostics.Where(diagnostic =>
            diagnostic.IsWarningAsError ||
            diagnostic.Severity == DiagnosticSeverity.Error);

        foreach (Diagnostic diagnostic in failures)
        {
            sb.AppendLine(diagnostic.GetMessage());
        }

        return sb.ToString();
    }
}

（显示的代码不用于工作目的，它被简化以演示问题）

提前致谢，

4

1 回答 1

2

解决方案是添加特定的引用：

MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "System.Linq.Expressions.dll")),
MetadataReference.CreateFromFile(Path.Combine(runtimeAssemblyDirectory, "System.Linq.dll")),
于 2019-02-28T03:31:58.040 回答