Question

我很难过。我需要帮助。我有一个带有重复患者地址数据的DTO对象。我只需要获得唯一的地址。

Dim PatientAddressDto = New List(Of PatientAddress)

{Populate PatientAddressDto with lots of duplicate data}

PatientAddressDto = (From d In PatientAddressDto
                    Group d By PatientAddressDtoGrouped = New PatientAddress With {
                                                              .Address1 = d.Address1,
                                                              .Address2 = d.Address2,
                                                              .City = d.City,
                                                              .State = d.State,
                                                              .Zip = d.Zip
                                                              }
                  Into Group
                  Select New PatientAddress With {
                                                  .Address1 = PatientAddressDtoGrouped.Address1,
                                                  .Address2 = PatientAddressDtoGrouped.Address2,
                                                  .City = PatientAddressDtoGrouped.City,
                                                  .State = PatientAddressDtoGrouped.State,
                                                  .Zip = PatientAddressDtoGrouped.Zip
                                                  }).ToList()

我试过以下但没有运气：

PatientAddressDto = (From d In PatientAddressDto
                    Select New PatientAddress With {
                                                  .Address1 = d.Address1,
                                                  .Address2 = d.Address2,
                                                  .City = d.City,
                                                  .State = d.State,
                                                  .Zip = d.Zip
                                                    }).Distinct

以及

PatientAddressDto = PatientAddressDto.GroupBy(Function(p) New PatientAddress With {
                                                  .Address1 = p.Address1,
                                                  .Address2 = p.Address2,
                                                  .City = p.City,
                                                  .State = p.State,
                                                  .Zip = p.Zip
                                                    })

Answer 1

您可以使用anonymous type并使用Key keyword以使相等操作符合您的预期（C＃不需要）。

通过指定Key前缀更改您的分组并删除PatientAddress用法：

Group d By PatientAddressDtoGrouped = New With {
    Key .Address1 = d.Address1,
    Key .Address2 = d.Address2,
    Key .City = d.City,
    Key .State = d.State,
    Key .Zip = d.Zip
}

Answer 2

我找到了以下代码，它基本上完成了我想要的分组，并将新对象填充为PatientAddress类型，因此无需使用匿名对象和关键字Key。

也许有人可以解释它，此刻我不能。祝你有愉快的一天。

Dim PatientAddressDto = New List(Of PatientAddress)

{Populate PatientAddressDto with lots of duplicate data}

PatientAddressDto = (From d In PatientAddressDto
                    Group d By d.Address1,
                                d.Address2,
                                d.City,
                                d.State,
                                d.Zip Into g =
                    Group Let grp = New PatientAddress With {.Address1 = Address1,
                                                                .Address2 = Address2,
                                                                .City = City,
                                                                .State = State,
                                                                .Zip = Zip}
                    Select grp).ToList()

Answer 3

可能是因为PatientAddress未覆盖GetHashCode和Equals。另一种选择是我们anonymous type进行分组。试着写：

Group d By PatientAddressDtoGrouped = New With { Key .Address1 = d.Address1, ....

Linq Group on Multiple Fields - VB.NET，Anonymous，Key

3 个答案: