Question

我正在构建一个带有8个表连接的Dapper查询，但显然Dapper SqlMapper仅支持7个。

我在这篇article中读到，有一种重载需要n种类型：

public static IEnumerable<TReturn> Query<TReturn>(this IDbConnection cnn, 
  string sql, 
  Type[] types, 
  Func<object[], TReturn> map, 
  object param = null, 
  IDbTransaction transaction = null, 
  bool buffered = true, 
  string splitOn = "Id", 
  int? commandTimeout = null, 
  CommandType? commandType = null)

有人能给我一个如何使用它的简单例子吗？

这是我之前用于连接较少数量表的内容：

var sql = @"SELECT * FROM dbo.ComponentRelationship cr
                        JOIN dbo.ComponentRelationshipType crt ON crt.ComponentRelationshipTypeId = cr.ComponentRelationshipTypeId
                        JOIN dbo.Application fa ON fa.ApplicationId = cr.FromId
                        JOIN dbo.Application ta ON ta.ApplicationId = cr.ToId
                        ORDER BY fa.Name, ta.Name";
            result = connection.Query<ComponentRelationship, ComponentRelationshipType, Application, Application, ComponentRelationship>(sql,
                (cr, crt, fa, ft) =>
                {
                    cr.ComponentRelationshipTypeName = crt.Name;
                    cr.FromName = fa.Name;
                    cr.ToName = ft.Name;
                    return cr;
                }, splitOn: "ComponentRelationshipId,ComponentRelationshipTypeId,ApplicationId,ApplicationId");

Answer 1

我找到了答案here。

            const string sql = @"
                select 
                    rb.Id, rb.Name,
                    u1.*, u2.*, u3.*, u4.*, u5.*, u6.*, u7.*, u8.*, u9.*
                from #ReviewBoards rb
                    inner join #Users u1 on u1.Id = rb.User1Id
                    inner join #Users u2 on u2.Id = rb.User2Id
                    inner join #Users u3 on u3.Id = rb.User3Id
                    inner join #Users u4 on u4.Id = rb.User4Id
                    inner join #Users u5 on u5.Id = rb.User5Id
                    inner join #Users u6 on u6.Id = rb.User6Id
                    inner join #Users u7 on u7.Id = rb.User7Id
                    inner join #Users u8 on u8.Id = rb.User8Id
                    inner join #Users u9 on u9.Id = rb.User9Id";

            var types = new[] { typeof(ReviewBoard), typeof(User), typeof(User), typeof(User), typeof(User), typeof(User), typeof(User), typeof(User), typeof(User), typeof(User) };

            Func<object[], ReviewBoard> mapper = (objects) =>
            {
                var board = (ReviewBoard)objects[0];
                board.User1 = (User)objects[1];
                board.User2 = (User)objects[2];
                board.User3 = (User)objects[3];
                board.User4 = (User)objects[4];
                board.User5 = (User)objects[5];
                board.User6 = (User)objects[6];
                board.User7 = (User)objects[7];
                board.User8 = (User)objects[8];
                board.User9 = (User)objects[9];
                return board;
            };

            var data = connection.Query<ReviewBoard>(sql, types, mapper).ToList();

具有n个导航属性的Dapper查询示例

1 个答案: