Question

让我说我的联系人以平展的形式存储了联系人，这样我就可以这样查询：

SELECT Name, HomeHouseNumber, HomePostcode, WorkHouseNumber, WorkPostcode FROM Contacts

我想在我的C＃代码中添加一些结构，并且可以简单地定义一个带有家庭和工作地址的联系人。

class Address
{
    public string HouseNumber { get; set; }
    public string Postcode { get; set; }
}

class Contact
{
    public string Name { get; set; }
    public Address HomeAddress { get; set; }
    public Address WorkAddress { get; set; }
}

我发现我可以使用多映射确实通过对select中的列进行别名来提取家庭地址，如下所示：

IEnumerable<Contact> GetContacts()
{
    return Connection.Query<Contact, Address, Address, Contact>(
        "SELECT Name, HomeHouseNumber as HouseNumber, HomePostcode as Postcode, WorkHouseNumber, WorkPostcode FROM Contacts",
        (contact, home, work) =>
        {
            contact.HomeAddress = home;
            contact.WorkAddress = work;
            return contact;
        },
        splitOn: "HouseNumber,WorkHouseNumber");
}

但是，我不能将工作地址列别名，以便映射它们。 Dapper可以为我执行此映射，还是必须手动执行此操作？

Answer 1

令人难以置信的是，解决方案是为列提供相同的别名。我不认为SQL会允许这样做，但确实如此，Dapper完全映射它。

IEnumerable<Contact> GetContacts()
{
    return Connection.Query<Contact, Address, Address, Contact>(
        "SELECT Name, HomeHouseNumber as HouseNumber, HomePostcode as Postcode, WorkHouseNumber as HouseNumber, WorkPostcode as Postcode FROM Contacts",
        (contact, home, work) =>
        {
            contact.HomeAddress = home;
            contact.WorkAddress = work;
            return contact;
        },
        splitOn: "HouseNumber,HouseNumber");
}

Dapper多映射两种相同类型的属性

1 个答案: