Question

我有一个通用方法，我给它任何类型T的对象和一个属性列表，它将返回该对象，该对象具有由列表定义的属性设置为空

这是我的代码

class Program
{
    static void Main(string[] args)
    {
        var orderDto = new OrderDto();
        orderDto.Nominal = "1";
        orderDto.OrderId = "2";
        orderDto.Type = "3";

        var clean = FieldCleaner.Clean(orderDto, "OrderId");
    }
}

public class FieldCleaner
{
    public static T Clean<T>(T dto, params string[] properties) // I want in compilation time, have autocompletion that tell user the value of properties can only be a property name of the type T
    {
        var propertyInfos = dto.GetType().GetProperties();
        foreach (var propertyInfo in propertyInfos)
        {
            foreach (var property in properties)
            {
                if (propertyInfo.Name == property)
                {
                    propertyInfo.SetValue(dto, null);
                }
            }
        }

        return dto;
    }
}

public class OrderDto
{
    public string OrderId { get; set; }
    public string Nominal { get; set; }
    public string Type { get; set; }
}

我的问题在代码上方的注释中。我不喜欢字符串类型[]，我想要打字稿中的 T键之类的东西

我正在使用具有最新.NET核心的最新C＃版本

Answer 1

释义一下：

///我想要Visual Studio中的自动完成列表来告诉程序员T的哪些属性可用

问题是类型T可能是任何内容。您必须能够在完全不同的程序集中使用此代码，Visual Studio和编译器都不会在编译时知道您的T。

我不会说这是不可能的。 Visual Studio具有非常好的可扩展性，尤其是现在我们有了Roslyn。但这就是您要做的：使用Roslyn分析代码并提供完成列表的自定义Visual Studio扩展。这不是内置在平台中。

Answer 2

尽管以下答案可以满足您的要求，但实际上没有意义，因为它只是不必要的。如果必须指定该属性，则最好直接设置它。

这里可能与您近在咫尺。我不相信您可以使用params，因为那样将要求所有TProp都属于同一类型。

在Visual Studio中，当您到达该时段时，您将获得智能感知：

using System;
using System.Linq.Expressions;
using System.Reflection;

public class Program
{
    public static void Main()
    {
        var orderDto = new OrderDto
        {
            Id = 1,
            Name = "Name",
            CreatedOn = DateTime.UtcNow,
            CompletedOn = DateTime.UtcNow.AddMinutes(30),
            Misc = Guid.NewGuid()
        };

        Console.WriteLine($"{orderDto.Id} {orderDto.Name} {orderDto.CreatedOn} {orderDto.CompletedOn} {orderDto.Misc}");

        orderDto.DefaultFor(x => x.Id, x => x.Name, x => x.CreatedOn, x => x.CompletedOn);

        Console.WriteLine($"{orderDto.Id} {orderDto.Name} {orderDto.CreatedOn} {orderDto.CompletedOn} {orderDto.Misc}");
    }
}

public static class ObjectExtensions
{
    public static void DefaultFor<TObject, TProp1, TProp2, TProp3, TProp4>(this TObject instance, 
        Expression<Func<TObject, TProp1>> selector1, 
        Expression<Func<TObject, TProp2>> selector2,
        Expression<Func<TObject, TProp3>> selector3,
        Expression<Func<TObject, TProp4>> selector4)
        where TObject : class
    {
        DefaultFor(instance, selector1, selector2, selector3);
        DefaultFor(instance, selector4);
    }

    public static void DefaultFor<TObject, TProp1, TProp2, TProp3>(this TObject instance, 
        Expression<Func<TObject, TProp1>> selector1, 
        Expression<Func<TObject, TProp2>> selector2,
        Expression<Func<TObject, TProp3>> selector3)
        where TObject : class
    {
        DefaultFor(instance, selector1, selector2);
        DefaultFor(instance, selector3);
    }

    public static void DefaultFor<TObject, TProp1, TProp2>(this TObject instance, 
        Expression<Func<TObject, TProp1>> selector1, 
        Expression<Func<TObject, TProp2>> selector2)
        where TObject : class
    {
        DefaultFor(instance, selector1);
        DefaultFor(instance, selector2);
    }

    public static void DefaultFor<TObject, TProp>(this TObject instance, Expression<Func<TObject, TProp>> selector)
        where TObject : class
    {
        if (instance == null)
            throw new ArgumentNullException();

        var memberExpression = (MemberExpression)selector.Body;
        var property = (PropertyInfo)memberExpression.Member;

        property.SetValue(instance, default(TProp));
    }
}

public class OrderDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime CreatedOn { get; set; }
    public DateTime? CompletedOn { get; set; }
    public Guid Misc { get; set; }
}

DotNetFiddle Example

输出：

1名称3/29/2019 5:14:06 AM 3/29/2019 5:44:06 AM 3800be41-7fe1-42da-ada5-4fe33ac04a84

0 1/1/0001 12:00:00 AM 3800be41-7fe1-42da-ada5-4fe33ac04a84

具有参数是类的属性的类型

2 个答案: