Dapper-开源小型ORM

Posted 2020-07-12 巴夫 - Ryan - YZR

 一些关于Dapper的介绍：

 1.Dapper是一个轻型的开源ORM类，代码就一个SqlMapper.cs文件，编译后就40多K的一个很小的Dll. 

 2.Dapper支持mysql,SqlLite,Mssql2000,Mssql2005,Oracle等一系列的数据库

 3.Dapper的r支持多表并联的对象。支持一对多 多对多的关系。并且没侵入性。

 4.Dapper原理通过Emit反射IDataReader的序列队列，来快速的得到和产生对象。性能提升了很多；（比采用常规的反射）并且无须迁就数据库的设计。

 Dapper源码下载链接：

 点击这里下载dapper源代码。

 Demo:

           var connection = GetOpenConnection();

            var guid = Guid.NewGuid();
            string id = "6e2a106d-d838-48b9-ac74-ad604457bba2";

            //1泛型
            var dog = connection.Query<Dog>("select * from Dog where Id = @Id", new { Id = id });
            
            //2 动态解析
            var rows = connection.Query("select * from Dog where Id = @Id", new { Id = id }).ToList();
            foreach (dynamic item in rows)
            {
                 String 黑客 = item.Name;
            }

Query

 

            //3.执行不返回结果
            int result=connection.Execute("insert into Dog values(@age,@id,@name,@weight,@ignoredproperty)", new { age = 49, id = Guid.NewGuid(), name = "YZR", weight = 117.5, ignoredproperty = 1 });

Execute

            //4.批量Execute
            List<Dog> list = new List<Dog>();
            list.Add(new Dog() { Age = 9, Id = Guid.NewGuid(), Name = "ZXX", Weight = 120 });
            list.Add(new Dog() { Age = 9, Id = Guid.NewGuid(), Name = "WMJ", Weight = 120 });
            List<dynamic> paramsList = new List<dynamic>();
            foreach (Dog item in list)
            {
                paramsList.Add(new { age = item.Age, id = item.Id, name = item.Name, weight = item.Weight, ignoredproperty = 1 });
            }
            int result = connection.Execute("insert into Dog values(@age,@id,@name,@weight,@ignoredproperty)", paramsList);

批量Execute

            //5.In操作
            dog = connection.Query<Dog>("select * from Dog where id in @ids", new { ids = new String[] { "6e2a106d-d838-48b9-ac74-ad604457bba3", "6e2a106d-d838-48b9-ac74-ad604457bba2", "535dab3a-d3c1-4cb0-b8f7-63351f491056" } });
            //等价于
            dog = connection.Query<Dog>("select * from Dog where id in (@id1,@id2,@id3)", new { id1 = "6e2a106d-d838-48b9-ac74-ad604457bba3", id2 = "6e2a106d-d838-48b9-ac74-ad604457bba2", id3 = "535dab3a-d3c1-4cb0-b8f7-63351f491056" });

In操作

            //数据库要建立主外键关系
            var sql =
                      @"select p.*,u.* from Dog p 
                                    left join Owner u on u.OwnerId = p.Id 
                                     where p.id=@id Order by p.Id";
            Dog d = null;
            var t = connection.Query(sql, new { id = "6e2a106d-d838-48b9-ac74-ad604457bba2" });
            var data = connection.Query<Dog, Owner, Dog>(sql, (post, user) =>
            {
                if (d == null || d.Id != post.Id)
                {
                    d = post;
                }
                if (user != null)
                {
                    d.user.Add(user);
                }
                return post;
            }, new { id = "6e2a106d-d838-48b9-ac74-ad604457bba2" });

一对多关系

            //多查询的结果集
            sql =
                 @"select * from Dog where Id = @id
                   select * from Owner";

            using (var multi = connection.QueryMultiple(sql, new { id = "6e2a106d-d838-48b9-ac74-ad604457bba3" }))
            {

                 var data = multi.Read<Dog>().ToList();
                 var owner = multi.Read<Owner>().ToList();
             }

QueryMultiple

            //事务

            using (connection)
            {
                //开始事务
                IDbTransaction transaction = connection.BeginTransaction();
                try
                {
                    string query = "update Dog set Age=Age+1 where Id=@Id";
                    string query2 = "update Dog set Weight=Weight+1.0 where Id=@Id";
                    connection.Execute(query, new { Id = "71fff309-c7c9-4f64-b588-0a03e27459ba" }, transaction, null, null);
                    connection.Execute(query2, new { Id = "71fff309-c7c9-4f64-b588-0a03e27459ba" }, transaction, null, null);
                    //提交事务
                    transaction.Commit();
                }
                catch (Exception ex)
                {
                    //出现异常，事务Rollback
                    transaction.Rollback();
                    throw new Exception(ex.Message);
                }
            }

IDbTransaction

            //存储过程

            var p = new DynamicParameters();
            //实例1
            //p.Add("@result", dbType: DbType.Int32, direction: ParameterDirection.Output);
            //var user = connection.Query("Test", p, commandType: CommandType.StoredProcedure);
            //int totalCount = p.Get<int>("@result");

            //实例2
            //注意点：调用如果使用query，那么存储过程需要有select结果集
            //p.Add("@result", dbType: DbType.Int32, direction: ParameterDirection.Output);
            //p.Add("@rowcount", dbType: DbType.Int32, direction: ParameterDirection.ReturnValue);
            //var user = connection.Query("TestValue", p, commandType: CommandType.StoredProcedure);
            //int re = p.Get<int>("@result");
            //int ro = p.Get<int>("@rowcount");

            //实例3
            //存储过程分页需要row_number() over( order by id)这个排序的id需要指定
            p.Add("@PageIndex", 1, dbType: DbType.Int32, direction: ParameterDirection.Input);
            p.Add("@PageSize", 3, dbType: DbType.Int32, direction: ParameterDirection.Input);
            p.Add("@TableName", "Dog", dbType: DbType.String, direction: ParameterDirection.Input);
            p.Add("@Where", " 1=1 order by id asc ", dbType: DbType.String, direction: ParameterDirection.Input);
            //p.Add("@rowcount", dbType: DbType.Int32, direction: ParameterDirection.Output);
            p.Add("@rowcount", dbType: DbType.Int32, direction: ParameterDirection.ReturnValue);
            var result = connection.Query("SelectBase", p, commandType: CommandType.StoredProcedure);

            int count = p.Get<int>("@rowcount");

Procedure

            //切换数据库
            connection.ChangeDatabase("数据库名称");

ChangeDatabase

 

Demo源代码下载

点击这里下载