LINQ to Objects .Distinct()不会拉出不同的对象

Question

我有两种方法可以对客户进行模糊搜索.一个是缩写名称,另一个是客户的全名.当我拿这两个结果集然后将它们结合在一起时(我已经读过几个地方应该删除不同的值)我得到重复.认为我需要做的就是调用这个.Distinct()方法,我还是会重复一遍.我是否需要在客户对象中实现一些比较功能？我的代码:

        Dim shortNameMatch As List(Of ICustomer) = CustomerLibrary.GetCustomersByShortName(term)
        Dim custNameMatch As List(Of ICustomer) = CustomerLibrary.GetCustomersByCustName(term)
        Dim allMatch = (From a In (From s In shortNameMatch Select s).Union(From c In custNameMatch Select c) Select a).Distinct()

Answer 1

您需要创建一个相等比较器并在Union或中使用它Distinct:

Public Class MyComparer
    Implements IEqualityComparer(Of ICustomer)

    Public Overloads Function Equals(ByVal x As ICustomer, ByVal y As ICustomer) _
        As Boolean Implements _
        System.Collections.Generic.IEqualityComparer(Of ICustomer).Equals
        Return ((x.id = y.id) AndAlso (x.title = y.title))
    End Function
    Public Overloads Function GetHashCode(ByVal obj As ICustomer) _
        As Integer Implements _
        System.Collections.Generic.IEqualityComparer(Of ICustomer).GetHashCode
        Return Me.GetHashCode()
    End Function
End Class

用法示例:

Dim allMatch = shortNameMatch.Union(custNameMatch).Distinct(New MyComparer())
Dim allMatch = shortNameMatch.Union(custNameMatch, New MyComparer())