我有一个名为employee的表，有几个列，如EmpID,FirstName,MiddleName,LastName,Address,EmailID,RegionID,DesgID，我使用Dapper .Net和扩展来处理SQL Server数据库。我使用Dapper SqlExtensions插入，更新，删除功能并使用Dapper multimapper选项来填充详细信息。所以我在上面的employee表
[Table("employee")] //To map the table to class
public class EmployeeModel
{
[Key] //Denote primary key
public Int32 EmpID { get; set; }
[Column("FirstName")] //Trying to map table column FirstName to variable First (Fails)
public string First { get; set; }
public string MiddleName { get; set; }
public string LastName { get; set; }
public string Address { get; set; }
public string EmailID { get; set; }
public Int32 RegionID { get; set; }
public RegionModel Region { get; set; }
public DesignationModel Designation { get; set; }
public Int32 DesgID { get; set; }
public Int32 Add(EmployeeModel Details)
{
try
{
using (var connection = DBProviderFactory.GetOpenConnection()) //Creating IDbConnection Here
{
return Convert.ToInt32(connection.Insert(Details)); //Using Dapper Extension To Insert New Employee Details
}
}
catch (Exception ex)
{
return -1;
}
}
public Int32 Update(EmployeeModel Details)
{
try
{
using (var connection = DBProviderFactory.GetOpenConnection())
{
return Convert.ToInt32(connection.Update(Details)); //Using Dapper Extension to Update Employee Details
}
}
catch (Exception ex)
{
return -1;
}
}
public IEnumerable<EmployeeModel> AllEmployees()
{
try
{
using (var connection = DBProviderFactory.GetOpenConnection())
{
//Using multi mapper in Dapper to Fill All Employee Details such as region,state,country,designation details etc..
string query = @"select e.EmpID,e.FirstName,e.MiddleName,e.LastName,e.Address,e.EmailID
,r.RegionID as RID,r.Region,s.StateID,s.State,c.CountryID,c.Country,d.DesgID as DID,d.Designation
from employee as e inner join region as r on e.RegionID=r.RegionID
inner join state as s on r.StateID=s.StateID inner join country as c on
s.CountryID=c.CountryID inner join designation as d on e.DesgID=d.DesgID";
return connection.Query<EmployeeModel, RegionModel, StateModel, CountryModel,DesignationModel, EmployeeModel>(query,
(employee, region, state, country, designation) =>
{
employee.Region = region;
region.State = state;
state.Country = country;
employee.Designation = designation;
return employee;
}, splitOn: "RID,StateID,CountryID,DID");
}
}
catch (Exception ex)
{
return null;
}
}
}
public class EmployeeModelMapper : ClassMapper<EmployeeModel>
{
public EmployeeModelMapper()
{
Map(m => m.Region).Ignore();
Map(m => m.Designation).Ignore();
Map(m => m.First).Column("FirstName"); //Trying to map table column FirstName to variable First (Fails in the case of Multimapping)
AutoMap();
}
}
在上面的示例中，我尝试将表列FirstName映射到类变量First但是在使用Dapper运行Query时失败connection.Query()请参阅{{1 AllEmployees()类中的方法。
我尝试使用Dapper Mapper扩展的另一个选项，也可以在上面的代码中找到，请参考EmployeeModel类。
我的问题：
如何将所有表列映射到对应的类变量，以便在Dapper和扩展中使用。
答案 0 :(得分：2)
默认情况下，Dapper不支持Column和Key等属性属性。
此处有两个选项，以太网调整您的查询以使用AS关键字更改结果集中的列名称以匹配您的属性名称，这是最简单的选项。
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using Dapper;
using Newtonsoft.Json;
using Repository.DTO;
namespace Repository.Repositories
{
public class EmployeeRepo
{
public IEnumerable<EmployeeModel> AllEmployees()
{
try
{
using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Read"].ConnectionString))
{
const string query = @"select EmpID, FirstName [First] from employee";
return connection.Query<EmployeeModel>(query);
}
}
catch (Exception e)
{
Console.WriteLine(JsonConvert.SerializeObject(e));
throw;
}
}
}
}
如果无法做到这一点，您可以尝试提供自己的SqlMapper.ITypeMap实现。
许多人已经以许多不同的方式做到了这一点。我个人是Dapper-FluentMap的粉丝。
这将是你的DTO。我在DTO上嵌入了mapper配置以便于配置。请注意，您只需列出映射中与返回的列名不同的列。在我们的示例中，只需要First属性，因为EmpId属性与结果集中的列名称相同。
using Dapper.FluentMap.Mapping;
namespace Repository.DTO
{
public class EmployeeModel
{
public int EmpId { get; set; }
public string First { get; set; }
public class EmployeeModelMap : EntityMap<EmployeeModel>
{
public EmployeeModelMap()
{
Map(p => p.First).ToColumn("FirstName");
}
}
}
}
下一步是初始化您的映射。
using Dapper.FluentMap;
using Repository.DTO;
namespace Repository
{
public class Bootstrap
{
public static void Map()
{
FluentMapper.Initialize(config =>
{
config.AddMap(new EmployeeModel.EmployeeModelMap());
});
}
}
}
然后就是这样。
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using Dapper;
using Newtonsoft.Json;
using Repository.DTO;
namespace Repository.Repositories
{
public class EmployeeRepo
{
public IEnumerable<EmployeeModel> AllEmployees()
{
try
{
using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Read"].ConnectionString))
{
const string query = @"select EmpID, FirstName from employee";
return connection.Query<EmployeeModel>(query);
}
}
catch (Exception e)
{
Console.WriteLine(JsonConvert.SerializeObject(e));
throw;
}
}
}
}
答案 1 :(得分：1)
一种简单的方法是将SQL select语句更改为使用AS，它将自动映射。
所以而不是：
string query = @"select e.EmpID,e.FirstName, ....
你只需要
string query = @"select e.EmpID,e.FirstName as First, ....