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介绍
Oracle 数据库功能强大，在企业环境中使用广泛。在 ASP.NET Core 应用程序中使用 Oracle 存储过程时，处理输出参数可能具有挑战性。本教程将指导您完成使用 Dapper（适用于 . NET 的轻量级 ORM（对象关系映射器））解锁 Oracle 存储过程输出参数的过程。
先决条件
在开始之前，请确保您已准备好以下内容。
- Visual Studio 2019 或更高版本
- .NET Core SDK 3.1 或更高版本
- Oracle 数据库（您可以使用 Oracle 数据库 XE 进行开发）
- 具有 C#、ASP.NET Core 和 SQL 的基础知识
设置项目
创建 ASP.NET 核心项目
打开 Visual Studio 并创建一个新的 ASP.NET Core 控制台应用程序项目。
安装 NuGet 包
您需要安装 Dapper 和 Oracle.ManagedDataAccess.Core 包。
创建 Oracle 存储过程
让我们在 Oracle 中创建一个简单的存储过程，它接受一个输入参数并返回一个输出参数。
CREATE OR REPLACE PROCEDURE DEMO.SAVE_EMPLOYEE_DETAILS (V_NAME IN VARCHAR2,V_ADDRESS IN VARCHAR2,V_DEPARTMENT IN VARCHAR2,V_POSITION IN VARCHAR2,O_EMP_ID OUT VARCHAR2,O_ERROR OUT VARCHAR2
)
ASV_EMP_ID VARCHAR2 (10);
BEGIN-- GENERATE EMPLOYEE IDSELECT DEMO.EMP_SEQ.NEXTVAL INTO V_EMP_ID FROM DUAL;-- INSERT EMPLOYEE DETAILSINSERT INTO DEMO.EMPLOYEE_DETAILS (EMP_ID,NAME,ADDRESS,DEPARTMENT,POSITION) VALUES (V_EMP_ID,V_NAME,V_ADDRESS,V_DEPARTMENT,V_POSITION);-- SET OUTPUT EMPLOYEE IDO_EMP_ID := V_EMP_ID;-- RESET ERROR OUTPUTO_ERROR := NULL;
EXCEPTIONWHEN OTHERS THENO_ERROR := 'FAILED TO SAVE EMPLOYEE DETAILS. ' || SQLERRM;ROLLBACK;RETURN;
END SAVE_EMPLOYEE_DETAILS;
/
连接到 Oracle 数据库
使用 SQL*Plus、SQL Developer、Toad 或任何其他 Oracle 客户端工具连接到您的 Oracle 数据库。
实现 ASP.NET 核心应用程序
添加 OracleDynamicParameters 类
using Dapper;
using Oracle.ManagedDataAccess.Client;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;namespace DapperOracleDemo
{public class OracleDynamicParameters : SqlMapper.IDynamicParameters{private readonly DynamicParameters dynamicParameters = new DynamicParameters();// 使用DynamicParameters存储一般参数private readonly List<OracleParameter> oracleParameters = new List<OracleParameter>();// 使用List<OracleParameter>存储Oracle特定的参数public void Add(string name, OracleDbType oracleDbType, ParameterDirection direction, object value = null, int? size = null){// 创建并添加一个OracleParameter对象到参数列表中OracleParameter item = ((!size.HasValue) ? new OracleParameter(name, oracleDbType, value, direction) : new OracleParameter(name, oracleDbType, size.Value, value, direction));oracleParameters.Add(item);}public void Add(string name, OracleDbType oracleDbType, ParameterDirection direction){// 创建并添加一个没有默认值的OracleParameter对象到参数列表中OracleParameter item = new OracleParameter(name, oracleDbType, direction);oracleParameters.Add(item);}public void AddParameters(IDbCommand command, SqlMapper.Identity identity){// 将一般参数添加到命令对象中((SqlMapper.IDynamicParameters)dynamicParameters).AddParameters(command, identity);// 将Oracle特定的参数添加到命令对象中(command as OracleCommand)?.Parameters.AddRange(oracleParameters.ToArray());}public T Get<T>(string name){// 获取指定名称的参数值var parameter = oracleParameters.SingleOrDefault(t => t.ParameterName == name);object val = parameter?.Value;if (val == DBNull.Value){if (default(T) != null){// 如果尝试将DBNull值转换为非可空类型，抛出异常throw new ApplicationException("Attempting to cast a DBNull to a non nullable type! Note that out/return parameters will not have updated values until the data stream completes (after the 'foreach' for Query(..., buffered: false), or after the GridReader has been disposed for QueryMultiple)");}return default;}return (T)val;}public T Get<T>(int index){// 获取指定索引的参数值var parameter = oracleParameters[index];object val = parameter?.Value;if (val == DBNull.Value){if (default(T) != null){// 如果尝试将DBNull值转换为非可空类型，抛出异常throw new ApplicationException("Attempting to cast a DBNull to a non nullable type! Note that out/return parameters will not have updated values until the data stream completes (after the 'foreach' for Query(..., buffered: false), or after the GridReader has been disposed for QueryMultiple)");}return default;}return (T)val;}}
}
添加 OracleDataAccessObject 类
using Dapper;
using Oracle.ManagedDataAccess.Client;
using System.Data;namespace DapperOracleDemo
{public class OracleDataAccessObject{private readonly string _ConnectionString;// 构造函数，初始化连接字符串public OracleDataAccessObject(string ConnectionString){_ConnectionString = ConnectionString;}// 获取Oracle数据库连接private IDbConnection GetOracleConnection(){return new OracleConnection(_ConnectionString);}// 执行带参数的存储过程public dynamic OracleSProcWithParam(string sql, OracleDynamicParameters param){// 使用using语句确保IDbConnection在使用后被正确关闭和释放using IDbConnection cnn = GetOracleConnection();CommandType? commandType = CommandType.StoredProcedure;// 执行存储过程return cnn.Execute(sql, param, null, null, commandType);}}
}
添加员工输入和输出 Dto
namespace DapperOracleDemo
{public class EmployeeInputDto{public string NAME { get; set; }public string ADDRESS { get; set; }public string DEPARTMENT { get; set; }public string POSITION { get; set; }}
}
namespace DapperOracleDemo
{public class EmployeeOutputDto{public string EMP_ID { get; set; }public string ERROR { get; set; }}
}
using Oracle.ManagedDataAccess.Types;
namespace DapperOracleDemo
{public class SpReturnModel{public dynamic ID { get; set; }public OracleString ErrorMsg { get; set; }}
}
配置连接字符串
static class Config
{public static string OracleDBConnectionString => "Data Source=192.168.29.1:1521/DEMODB;User Id=DEMO;Password=demo@123;";public static string SP_SAVE_EMPLOYEE_DETAILS = "DEMO.SAVE_EMPLOYEE_DETAILS";
}
添加 SaveEmployeeDetails() 方法
static SpReturnModel SaveEmployeeDetails(EmployeeInputDto dto)
{var oraDao = new OracleDataAccessObject(Config.OracleDBConnectionString);var oracleParam = new OracleDynamicParameters();oracleParam.Add("V_NAME", OracleDbType.Varchar2, ParameterDirection.Input, dto.NAME);oracleParam.Add("V_ADDRESS", OracleDbType.Varchar2, ParameterDirection.Input, dto.ADDRESS);oracleParam.Add("V_DEPARTMENT", OracleDbType.Varchar2, ParameterDirection.Input, dto.DEPARTMENT);oracleParam.Add("V_POSITION", OracleDbType.Varchar2, ParameterDirection.Input, dto.POSITION);oracleParam.Add("O_EMP_ID", OracleDbType.Varchar2, ParameterDirection.Output, size: 20);oracleParam.Add("O_ERROR", OracleDbType.Varchar2, ParameterDirection.Output, size: 2000);var oracleQuery = Config.SP_SAVE_EMPLOYEE_DETAILS;oraDao.OracleSProcWithParam(oracleQuery, oracleParam);return GetSpOutParamResult(oracleParam, "O_EMP_ID");
}
static SpReturnModel GetSpOutParamResult(OracleDynamicParameters param, string idParam = "")
{SpReturnModel retMdl = new SpReturnModel(){ID = !string.IsNullOrEmpty(idParam) ? param.Get<dynamic>(idParam) : 0,ErrorMsg = param.Get<OracleString>("O_ERROR")};return retMdl;
}
测试应用程序
调用 SaveEmployeeDetails() 方法
static void Main(string[] args)
{var inDto = new EmployeeInputDto{NAME = "SURYA RAJ GHIMIRE",ADDRESS = "KATHMANDU, NEPAL",DEPARTMENT = "RESEARCH & DEVELOPMENT",POSITION = "SOFTWARE ENGINEER"};var resp = SaveEmployeeDetails(inDto);var outDto = new EmployeeOutputDto{EMP_ID = resp.ID is null ? null : (string)resp.ID,ERROR = resp.ErrorMsg.ToString()};Console.WriteLine("Employee id: " + outDto.EMP_ID);Console.WriteLine("Error: " + outDto.ERROR);Console.ReadLine();
}
运行应用程序
运行您的 ASP.NET Core 应用程序并查看控制台上的输出。
结论
在本教程中，我们介绍了如何使用 Dapper 处理 ASP.NET Core 应用程序中 Oracle 存储过程的输出参数。通过遵循这些步骤，您可以有效地将 Oracle 存储过程集成到 .NET 应用程序中，利用 Dapper 的强大功能和简单性进行数据库操作。