“选择”的定义在CSharpScript.EvaluateAsync

问题描述

我无法使此代码正常工作。似乎csharpscript.EvaluateAsync将无法理解Linq“选择”命令，即使我认为我正在向ScriptOptions添加适当的引用。这里的目标是使用EvaluateAsync运行基于字符串的Linq查询。多谢您的协助。

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?)
 */

解决方法

将程序集添加为引用是其中的一部分，但是要添加任何“使用指令”，则还应该使用AddImports()：

//..

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

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

//..