Dapper.Extension的基本使用

前言

     上一篇随笔写了Dapper的简单的使用,这次写一下Dapper.Extension的使用,它是Dapper的简单的封装扩展,可以通过实例化的对象赋值后进行增删改的操作以及分页,但是却不能进行多表查询的操作,这个需要自己来扩展吧。事务的操作的话和Dapper是一样的。

1.获取单个实体  

  这个比较简单直接传入id就可以获取返回的对象,如下所示:

        public Student ExtGet()
        {
            using(IDbConnection conn = new SqlConnection(sqlconnection))
            {
                return conn.Get<Student>(1);//这里只能传id查询,并且Student的字段必须与表字段匹配,多一个少一个都会报错.所以获取单个的对象感觉还是Dapper的原生语句好
                //return conn.Get<Student>(" select id,score,courseId,studentId from Student where id = 1 ");//会报nvarchar转换int报错
            }
        }

2.获取多个实体List

  具体代码以及注释如下所示:

        public List<Student> ExtList()
        {
            using (IDbConnection conn = new SqlConnection(sqlconnection))
            {
                IList<ISort> sortlist = new List<ISort>();
                sortlist.Add(new Sort { PropertyName = "id", Ascending = false });//排序条件

                IList<IPredicate> preList = new List<IPredicate>();
                preList.Add(Predicates.Field<Student>(o => o.id, Operator.Eq, 2));//搜索条件,Operator有很多种的类型如eq是等于、like相当于是sql的like用法还有Lt、Le等

                BetweenValues betweenValues = new BetweenValues();//搜索条件,between搜索两个值之间的数据
                betweenValues.Value1 = 1;
                betweenValues.Value2 = 6;
                preList.Add(Predicates.Between<Student>(o => o.id, betweenValues));

                var subPre = Predicates.Field<Student>(o => o.id, Operator.Eq, 3);//搜索条件,判断是否存在一个条件,后面的布尔参数如果是true表明不存在,false是存在
                preList.Add(Predicates.Exists<Student>(subPre,true));

                preList.Add(Predicates.Property<Student,Student>(o => o.id , Operator.Eq , t => t.id));//判断两个字段的关系,比如是否相等、大于、小于等和Field差不多,并不能用于两张表的字段判断

                IPredicateGroup predGroup = Predicates.Group(GroupOperator.Or, preList.ToArray());//确认多个搜索条件的连接方式AND 或者 OR
                var list = conn.GetList<Student>(predGroup, sortlist).ToList<Student>();
                return list;
                //以上代码生成的sql语句如下
                //exec sp_executesql N‘SELECT [Student].[id], [Student].[name], [Student].[sex], [Student].[tel] FROM [Student] 
                //WHERE (([Student].[id] = @id_0) 
                //OR
                // ([Student].[id] BETWEEN @id_1 AND @id_2) 
                //OR
                // (NOT EXISTS (SELECT 1 FROM [Student] WHERE ([Student].[id] = @id_3))) 
                //OR 
                //([Student].[id] = [Student].[id])) 
                //ORDER BY [Student].[id] DESC‘,N‘@id_0 int,@id_1 int,@id_2 int,@id_3 int‘,@id_0=2,@id_1=1,@id_2=6,@id_3=3
            }
        }

3.分页

  分页具体和GetList的方法是一样的,只是多了页码和每页数据数量参数,具体代码如下:

        public List<Student> ExtPageList()
        {
            using (IDbConnection conn = new SqlConnection(sqlconnection))
            {
                IList<ISort> sortlist = new List<ISort>();
                sortlist.Add(new Sort { PropertyName = "id", Ascending = false });//排序条件

                IList<IPredicate> preList = new List<IPredicate>();
                preList.Add(Predicates.Field<Student>(o => o.id, Operator.Eq, 2));
                IPredicateGroup predGroup = Predicates.Group(GroupOperator.Or, preList.ToArray());
                return conn.GetPage<Student>(predGroup,sortlist,1,10).ToList();
            }
        }

4.添加

        /// <summary>
        /// 添加,只能单条添加
        /// 通过传入组装好的类对象,就可以插入数据
        /// 如果没有数据会是NULL或者是数据库字段的默认值
        /// </summary>
        public void ExtAdd()
        {
            using (IDbConnection conn = new SqlConnection(sqlconnection))
            {
                Student student = new Student();
                student.name = "测试学生";
                student.sex = 1;
                //student.tel= "13222222222";
                int id = conn.Insert<Student>(student);//返回自增主键id
            }
        }

5.更新

        /// <summary>
        /// 更新,只能单条更新
        /// 如果有字段没有赋值的情况下,会导致数据库字段更新为NULL,
        /// 所以需要注意,保证数据的完整
        /// </summary>
        public void ExtUpdate()
        {
            using (IDbConnection conn = new SqlConnection(sqlconnection))
            {
                Student student = new Student();
                student.id = 1013;
                student.name = "测试学生";
                student.sex = 1;
                //student.tel= "13222222222";
                if (conn.Update<Student>(student))
                {
                    //成功
                }
                else 
                {
                    //失败
                }
            }
        }

6.删除

        /// <summary>
        /// 删除,只能单条删除
        /// 这边可以通过传入有id的实体或者Predicates对象来指定删除的条件,
        /// Predicates的话和List那部分的操作是一样的,可以参考ExtList种详细的使用
        /// </summary>
        public void ExtDel()
        {
            using (IDbConnection conn = new SqlConnection(sqlconnection))
            {
                Student student = new Student();
                student.id = 1020;
                var pre = Predicates.Field<Student>(o => o.id, Operator.Eq, 1017);
                if (conn.Delete<Student>(student))//或者conn.Delete<Student>(pre)
                {
                    //成功
                }
                else 
                {
                    //失败
                }
            }
        }

 

Dapper.Extension的基本使用

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