Csharp Dapper是否可以自动扩展类成员

发布于04月18日

有办法做到这样的事情吗？假设我有两个类:

public class Class_A
{
  public string Name {get;}
  public string Age  {get;}
  public int    Key  {get;}
}
public class Class_B
{
  public string Doors {get;}
  public string Windows  {get;}
  public int    Key  {get;}
}

然后是这样的组合类:

public class Class_C
{
  public Class_A CA {get;}
  public Class_B CB {get;}
}

现在假设我在说

_connection.Query<Class_C>("A SQL that returns results from JOIN of Clas_A and Class_B")

因此，它将能够somehow个知道要映射到什么领域. 因为否则我必须像这样再次复制粘贴Class_C中这两个类的字段:

public class Class_C
{
      public string Name {get;}
      public string Age  {get;}
      public string Doors {get;}
      public string Windows {get;}
}

推荐答案

按照您的 comments ，为了删除所有冗余，您可以将PropertyB添加到类A，并让Dapper将该属性绑定到您的查询结果.

public class A
{
    public string Name { get; set; }
    public string Age { get; set; }
    public int Key { get; set; }
    public B PropertyB { get; set; }
}

public class B
{
    public string Doors { get; set; }
    public string Windows { get; set; }
    public int Key { get; set; }
}

问题是:

SELECT * FROM A INNER JOIN B ON A.[Key] = B.[Key];

结果是按照顺序Name, Age, Key, Doors, Windows, Key的字段.

所以如果你除以Doors:

左边的组是A(Name, Age, Key)
右边的组是B(Doors, Windows, Key).

var results = connection.Query<A, B, A>(
        sql,
        (a, b) =>
        {
            a.PropertyB = b;
            return a;
        },
        splitOn: "Doors")
    .Distinct()
    .ToList();

Query<A, B, A>意味着左是类型A，右是类型B，组合结果是由上述函数生成的A.

有关更多信息，请参阅文档Dapper Multi-Mapping Result.支持One-To-One映射和One-to-Many.