我有一个名为 employee
的表,并且有多个列,例如 EmpID,FirstName,MiddleName,LastName,Address,EmailID,RegionID,DesgID
我正在使用 Dapper .Net和处理 SQL Server 数据库的扩展。我使用 Dapper SqlExtensions 来插入、更新、删除功能,并使用 Dapper multimapper 选项来填充细节。所以我在上面的 employee
表中使用了下面的类
[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
但在使用 Dapper connection 运行查询的情况下失败.Query()
引用 EmployeeModel
类中的 AllEmployees()
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,引用 EmployeeModelMapper
类。
我的问题:
如何将所有表列映射到相应的类变量,以便在 Dapper 和扩展中通用。
最佳答案
Dapper 默认不支持 Column
和 Key
等属性。
这里有两个选项,调整查询以使用 AS
关键字更改结果集中列的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;
}
}
}
}
或者,如果这不可能,您可以尝试提供自己的 SqlMapper.ITypeMap 实现。
很多人已经用许多不同的方式做到了这一点。我个人是Dapper-FluentMap的粉丝.
这将是您的 DTO。为了便于配置,我已将映射器配置嵌入到 DTO 中。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同名。
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());
});
}
}
}
那就这样吧。
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;
}
}
}
}
关于c# - 如何将数据库表列映射到 Dapper .Net 中的类属性,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21153567/