在添加新列表之前，使用Contains（）检查列表中是否存在多个对象值？

萤火虫

在将新对象添加到列表之前，如何检查对象中的多个属性以查看其是否存在于列表中？Contains（）在这里不起作用，那么应该怎么做呢？

我这里是一个大列表模型，我想将一些数据移植到一个没有重复值，具有唯一值的新的较短列表模型中。

谢谢..

public class Fee {
   public string Year { get; set; }
   public string Make { get; set; }
   public string Model { get; set; }
   public string Vin { get; set; }
   public string Color { get; set; }
}
public class Foo {
   public string Year { get; set; }
   public string Make { get; set; }
   public string Model { get; set; }
}

List<Fee> modelVehicles = new List<Fee>();
List<Foo> returnVehicles = new List<Foo>();

modelVehicles.Add(new Fee() { Year = "2001", Make = "Ford", Model = "Mustang", Vin = "111", Color = "Green" });
modelVehicles.Add(new Fee() { Year = "2001", Make = "Ford", Model = "Mustang", Vin = "222", Color = "Red" });
modelVehicles.Add(new Fee() { Year = "2001", Make = "Ford", Model = "Mustang", Vin = "333", Color = "Black" });

foreach(var v in modelVehicles)
{
    if (returnVehicles.Contains(new Foo { Year = v.Year, Make = v.Make, Model = v.Model }) == false)
    {
       returnVehicles.Add(
           new Foo {
               Year = v.Year,
               Make = v.Make, 
               Model = v.Model
           }
       );
    }
}

康拉德·科科萨（Konrad Kokosa）

您可以使用GroupByoperator，因为实际上您的操作是分组的：

returnVehicles = modelVehicles.GroupBy(x => new { x.Year, x.Make, x.Model }, 
                                       x => new Foo() {
                                           Year = x.Year,
                                           Make = x.Make,
                                           Model = x.Model
                                      },
                                      (key, values) => values.First())
                               .ToList();

并且如果您实现Equals并GetHashCode用于Foo：

public class Foo
{
    public string Year { get; set; }
    public string Make { get; set; }
    public string Model { get; set; }

    public override bool Equals(object obj)
    {
        Foo other = obj as Foo;
        if (other == null)
            return false;
        return string.Equals(Year, other.Year) && 
               string.Equals(Make, other.Make) && 
               string.Equals(Model, other.Model);
    }

    public override int GetHashCode()
    {
        int hash = 13;
        hash = (hash * 7) + Year.GetHashCode();
        hash = (hash * 7) + Make.GetHashCode();
        hash = (hash * 7) + Model.GetHashCode();
        return hash;
    }
}

这可以简化：

returnVehicles = modelVehicles.GroupBy(x => new Foo() {
                                               Year = x.Year,
                                               Make = x.Make,
                                               Model = x.Model
                                            }, 
                                       (key, values) => key)
                                .ToList();

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