Dapper，在.net的ORM中占有一席之地，用法简单，灵活，使用如下。但也带来一个问题，就是在单元测试时，Mock比较难办。

 public List<Goods> GetAllGoods(){using var con = new SqlConnection();var sql = "select * from Goodses";var list = con.Query<Goods>(sql, new { id = 1 }).ToList();return list;}

mock最好是一个接口，但Dapper是基于IDbConnection做的扩展方法，为了能把这些方法的功能抽出来到一个接口，这里要经过一个设计，来转嫁调用这些扩展方法，具体做法如下：

定义接口IGUIDapper.cs

    /// <summary>/// IDapperPlus接口/// </summary>public interface IDapperPlus{/// <summary>/// 连接/// </summary>public IDbConnection Connection{get;}/// <summary>/// Executes a single-row query, returning the data typed as type./// </summary>/// <param name="type">The type to return.</param>/// <param name="sql">The SQL to execute for the query.</param>/// <param name="param">The parameters to pass, if any.</param>/// <param name="transaction">The transaction to use, if any.</param>/// <param name="buffered">Whether to buffer results in memory.</param>/// <param name="commandTimeout">The command timeout (in seconds).</param>/// <param name="commandType">The type of command to execute.</param>/// <returns>A sequence of data of the supplied type; if a basic type(int, string, etc) is queried then the data from the first column in assumed, otherwise an instance is created per row, and a direct column-name===member-name mapping is assumed(case insensitive)./// 异常:T:System.ArgumentNullException:type is null./// </returns>IEnumerable<object> Query(Type type, string sql, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null);                       /// <summary>/// Execute parameterized SQL./// </summary>/// <param name="sql">The SQL to execute for this query.</param>/// <param name="param">The parameters to use for this query.</param>/// <param name="transaction">The transaction to use for this query.</param>/// <param name="commandTimeout">Number of seconds before command execution timeout.</param>/// <param name="commandType">Is it a stored proc or a batch?</param>/// <returns>The number of rows affected.</returns>int Execute(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null)//这里省略n多个方法}

DapperPlus.cs接口的实现类，这里把对Dapper基于IDbConnection扩展方法的调用，转到方法的实现中调用，实现方法与扩展方法完全相同。

    /// <summary>/// DapperPlus 类/// </summary>public class DapperPlus : IDapperPlus{protected IDbConnection _connection;/// <summary>/// 构造/// </summary>/// <param name="connection">连接</param>/// <param name="configuration">配置</param>public DapperPlus (IDbConnection connection, IConfiguration configuration){_connection = connection;_connection.ConnectionString = configuration.GetConnectionString("DefaultConnectionString");  }  /// <summary>/// 连接/// </summary>public IDbConnection Connection{get{return _connection;}}   /// <summary>/// Executes a single-row query, returning the data typed as type./// </summary>/// <param name="type">The type to return.</param>/// <param name="sql">The SQL to execute for the query.</param>/// <param name="param">The parameters to pass, if any.</param>/// <param name="transaction">The transaction to use, if any.</param>/// <param name="buffered">Whether to buffer results in memory.</param>/// <param name="commandTimeout">The command timeout (in seconds).</param>/// <param name="commandType">The type of command to execute.</param>/// <returns>A sequence of data of the supplied type; if a basic type(int, string, etc) is queried then the data from the first column in assumed, otherwise an instance is created per row, and a direct column-name===member-name mapping is assumed(case insensitive)./// 异常:T:System.ArgumentNullException:type is null./// </returns>public IEnumerable<object> Query(Type type, string sql, object param = null, IDbTransaction transaction = null, bool buffered = true, int? commandTimeout = null, CommandType? commandType = null){return _connection.Query(type, sql, param, transaction, buffered, commandTimeout, commandType);}/// <summary>/// Execute parameterized SQL./// </summary>/// <param name="sql">The SQL to execute for this query.</param>/// <param name="param">The parameters to use for this query.</param>/// <param name="transaction">The transaction to use for this query.</param>/// <param name="commandTimeout">Number of seconds before command execution timeout.</param>/// <param name="commandType">Is it a stored proc or a batch?</param>/// <returns>The number of rows affected.</returns>public int Execute(string sql, object param = null, IDbTransaction transaction = null, int? commandTimeout = null, CommandType? commandType = null){return _connection.Execute(sql, param, transaction, commandTimeout, commandType);}   //这里省略n多个实现方法     }    

Starup.cs中注入就ok了

public void ConfigureServices(IServiceCollection services)
{services.AddControllers();services.AddScoped<IDbConnection, SqlConnection>();services.AddScoped<IDapperPlus, DapperPlus>();
}

appsettings.json

  "ConnectionStrings": {"DefaultConnectionString": "server=127.0.0.1;uid=root;pwd=root;database=read_mysql_testdb"}