联盟ING两个自定义类返回重复 [英] Union-ing two custom classes returns duplicates

问题描述

我有两个自定义类， ChangeRequest 和 ChangeRequests ，其中 ChangeRequests 可以包含多个 ChangeRequest 实例。

I have two custom classes, ChangeRequest and ChangeRequests, where a ChangeRequests can contain many ChangeRequest instances.

public class ChangeRequests : IXmlSerializable, ICloneable, IEnumerable<ChangeRequest>,
    IEquatable<ChangeRequests> { ... }

public class ChangeRequest : ICloneable, IXmlSerializable, IEquatable<ChangeRequest>
    { ... }

我试图做的两个工会 ChangeRequests 实例。然而，重复似乎没有被删除。我的MSTest的单元测试如下：

I am trying to do a union of two ChangeRequests instances. However, duplicates do not seem to be removed. My MSTest unit test is as follows:

var cr1 = new ChangeRequest { CRID = "12" };
var crs1 = new ChangeRequests { cr1 };
var crs2 = new ChangeRequests
               {
                   cr1.Clone(),
                   new ChangeRequest { CRID = "34" }
               };
Assert.AreEqual(crs1[0], crs2[0], "First CR in both ChangeRequests should be equal");
var unionedCRs = new ChangeRequests(crs1.Union<ChangeRequest>(crs2));
ChangeRequests expected = crs2.Clone();
Assert.AreEqual(expected, unionedCRs, "Duplicates should be removed from a Union");

该测试的最后一行失败， unionedCRs 包含 CR1 。当我试图调试，并通过每行一步，我，以及在<$的第一行曾在 ChangeRequest.Equals（对象）第一行设置断点C $ C> ChangeRequest.Equals（ChangeRequest），但也被击中。为什么工会包含重复 ChangeRequest 实例

The test fails in the last line, and unionedCRs contains two copies of cr1. When I tried to debug and step through each line, I had a breakpoint in ChangeRequest.Equals(object) on the first line, as well as in the first line of ChangeRequest.Equals(ChangeRequest), but neither were hit. Why does the union contain duplicate ChangeRequest instances?

编辑：的要求，在这里在 ChangeRequests.Equals（ChangeRequests）：

public bool Equals(ChangeRequests other)
{
    if (ReferenceEquals(this, other))
    {
        return true;
    }

    return null != other && this.SequenceEqual<ChangeRequest>(other);
}

和这里的 ChangeRequests.Equals（对象）：

public override bool Equals(object obj)
{
    return Equals(obj as ChangeRequests);
}

编辑：我推翻的GetHashCode 两个 ChangeRequest 和 ChangeRequests ，但仍然在我的测试，如果我这样做的IEnumerable< ChangeRequest> unionedCRsIEnum = crs1.Union< ChangeRequest>（crs2）; ， unionedCRsIEnum 带的两个副本结束的 ChangeRequest 与 CRID 12

I overrode GetHashCode on both ChangeRequest and ChangeRequests but still in my test, if I do IEnumerable<ChangeRequest> unionedCRsIEnum = crs1.Union<ChangeRequest>(crs2);, unionedCRsIEnum ends up with two copies of the ChangeRequest with CRID 12.

编辑：的东西必须是与我的等于或的GetHashCode 实现的地方，因为 Assert.AreEqual（预期，unionedCRs。不同的（），明显的应该删除重复项）; 失败，并且的字符串表示有望和 unionedCRs.Distinct （）显示， unionedCRs.Distinct（）绝对有CR 12的两个副本。

something has to be up with my Equals or GetHashCode implementations somewhere, since Assert.AreEqual(expected, unionedCRs.Distinct(), "Distinct should remove duplicates"); fails, and the string representations of expected and unionedCRs.Distinct() show that unionedCRs.Distinct() definitely has two copies of CR 12.

推荐答案

请确保您的的GetHashCode 的实施是与你的等于 - 中 Enumerable.Union 方法确实出现了同时使用。

Make sure your GetHashCode implementation is consistent with your Equals - the Enumerable.Union method does appear to use both.

您应该从编译器得到一个警告，如果你已经实施之一，但不是其他;它仍然是由你来确保这两种方法相互一致。下面是规则的方便总结：的 http://stackoverflow.com/questions/371328/why-is-it-important-to-override-gethashcode-when-equals-method-is-overriden-in-c

You should get a warning from the compiler if you've implemented one but not the other; it's still up to you to make sure that both methods agree with each other. Here's a convenient summary of the rules: http://stackoverflow.com/questions/371328/why-is-it-important-to-override-gethashcode-when-equals-method-is-overriden-in-c

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