2

我在使此代码正常工作时遇到问题。即使我认为我正在添加对 ScriptOptions 的正确引用，CSharpScript.EvaluateAsync 似乎也无法理解 Linq 'Select' 命令。这里的目标是使用 EvaluateAsync 运行基于字符串的 Linq 查询。提前感谢您的帮助。

List<Dog> dogs = new List<Dog>();

dogs.Add(new Dog()
{ Name = "spike", Breed = "Poodle" });

dogs.Add(new Dog()
{ Name = "george", Breed = "Spaniel" });

dogs.Add(new Dog()
{ Name = "sammy", Breed = "Weimaraner" });


Console.WriteLine("Analyzing List");

// Func to return max string length of Breed Property in list of Dogs
int maxlen = dogs.Select(d => d.Breed.Trim().Length).OrderByDescending(d1 => d1).First();



// Recreated Func using Microsoft.CodeAnalysis.CSharp.Scripting.
var myLambda = "d => d.Select(d => d.Breed.Trim().Length).OrderByDescending(d1 => d1).First()";

Assembly[] assemblies = {
    typeof(Dog).Assembly,
    System.Reflection.Assembly.Load("System.Collections"),
    System.Reflection.Assembly.Load("System.Linq"),
    System.Reflection.Assembly.GetExecutingAssembly()
    
};

ScriptOptions options = ScriptOptions.Default.AddReferences(
             assemblies
            );

Func<List<Dog>, int> Dexprssn = await CSharpScript.EvaluateAsync<Func<List<Dog>, int>>(myLambda, options);
/*
   Error
        Microsoft.CodeAnalysis.Scripting.CompilationErrorException
        HResult=0x80131500
        Message=(1,8): error CS1061: 'Dog' does not contain a definition for 'Select' and no accessible 
            extension method 'Select' accepting a first argument of type 'Dog' could be found 
            (are you missing a using directive or an assembly reference?)
 */
4

1 回答 1

2

添加程序集作为引用是其中的一部分，但要添加任何“使用指令”，那么您还应该使用AddImports()：

//..

ScriptOptions options = ScriptOptions.Default.AddReferences(assemblies);

options = options.AddImports("System.Linq");

//..
于 2020-10-28T05:57:17.483 回答