如何调用在泛型基类中抽象定义的函数。
我有一个通用
class Class1<T> where T : class, new()
以及从中派生的多个类别,如
Class2: Class1<Class2>
Class3: Class1<Class3>
通用类有3个功能
1->接受一个动态对象,并将所有值放入派生对象中的相应属性
2->接受ID,在数据库中查找相应的行,将动态对象传递给func1并返回结果
3->返回表中所有行的listall函数
这是的通用代码
public abstract partial class Class1<T> where T : class, new()
{
public static EntityLayout EntityLayout { get; protected set; }
[TypeAttributes(TypeAttributes.Options.IsPrimary, TypeAttributes.Options.IsAutoIncrement)]
/// <summary> Automatically Incremented 64 bit Integer Primary Key
/// represents the Unique ID of each row in Table </summary>
public long ID { get; set; }
/// <summary> Converts the row returned from Database to Object </summary>
/// <param name="row"></param>
/// <returns></returns>
public abstract T GetDetails(dynamic row);
public static T GetDetails(long ID)
{
var row = Shared.SessionWrapper.Current.globaldbcon.QuerySingle("SELECT * FROM ["
+ EntityLayout.ContainerName + "].["
+ EntityLayout.TableName + "] WHERE ID=@0", ID);
if (row != null) return GetDetails(row);
return new T();
}
public static List<T> ListAll()
{
List<T> result = new List<T>();
foreach (var row in Shared.SessionWrapper.Current.globaldbcon.Query("SELECT * FROM ["
+ EntityLayout.ContainerName + "].["
+ EntityLayout.TableName + "]")) result.Add(GetDetails(row));
return result;
}
}
示例类实现
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Arinsys.Database;
namespace WebApplication1.Models
{
[EntityAttributes(EntityAttributes.Options.TestingEnabled)]
public class Class3 : Class1<Class3>
{
static Class3()
{
EntityLayout.DisplayName = "Users";
}
/// <summary> User ID of the User </summary>
public long UID { get; set; }
/// <summary> User ID of the User if defined in Universal Data Store </summary>
public long UDSID { get; set; }
/// <summary> Login ID of User </summary>
public string LoginID { get; set; }
/// <summary> Registered email of the user. If not set will be set same as LoginID </summary>
public string Registeredemail { get; set; }
[TypeAttributes(TypeAttributes.Options.IsPassword)]
/// <summary> Password of user </summary>
public string Password { get; set; }
/// <summary> A Unique Security Stamp used for activation/deactivation of account or similar intense tasks </summary>
public string SecurityStamp { get; set; }
/// <summary> Timezone ID of the Default Timezone of User </summary>
public string DefaultTimezone { get; set; }
/// <summary> Current Status of User </summary>
public string CurrentStatus { get; set; }
/// <summary> Discriminator which defines the type of user in multi-user heirarchy scenario </summary>
public string UserType { get; set; }
/// <summary> Number of failed login attempts in total or same session depending upon configuration. Resets after Successful Login </summary>
public short FailedAttempts { get; set; }
/// <summary> Date Time of Last Failed Login Attempt in UTC </summary>
public DateTime LastFailedAttempt { get; set; }
/// <summary> Date Time of Last Successful Login in UTC </summary>
public DateTime LastLogin { get; set; }
/// <summary> Creation Date of User Account in UTC </summary>
public DateTime CreationDate { get; set; }
public override Class3 GetDetails(dynamic row)
{
Class3 result = new Class3();
if (row != null)
{
result.ID = Convert.ToInt64(row.ID);
result.UID = Convert.ToInt64(row.UID);
result.UDSID = Convert.ToInt64(row.UDSID);
result.UserType = row.UserType;
result.LoginID = row.LoginID;
result.Password = row.Password;
result.Registeredemail = row.Registeredemail;
result.SecurityStamp = row.SecurityStamp;
result.DefaultTimezone = row.DefaultTimezone;
result.CurrentStatus = row.CurrentStatus;
result.FailedAttempts = Convert.ToInt16(row.FailedAttempts);
result.LastFailedAttempt = Convert.ToDateTime(row.LastFailedAttempt);
result.LastLogin = Convert.ToDateTime(row.LastLogin);
result.CreationDate = Convert.ToDateTime(row.CreationDate);
}
return result;
}
}
}
在发布之前,已经花了两周时间到处寻找答案,但找不到解决方案。
我只想让ListAll函数调用1st函数。由于它是抽象定义的,我确信派生类必须有一个实现(即使它可能只是抛出NotImplementException,但实现是有保证的)
我首先通过反射在泛型类中定义了1st函数的实现。虽然这很有效,但它非常慢,通过在控制器动作的开始/结束时启动/停止秒表来进行性能基准测试,仅100排就花了大约35秒,所以它肯定不适合生产使用。
注意事项
- 静态不能定义为抽象
- 无法从静态上下文访问实例成员
- 由于性能问题,无法使用反射
我想可能的解决方案是最接近的(但我无法理解如何在我的情况下使用它们)
- 将所有方法转换为实例方法并使用singleton
- 使用接口
- 在派生类中定义一个静态方法,并假设它将存在于所有类中,如果我这样做,那么在这种情况下如何访问T上的静态方法
我想要实现的是ListAll函数应该调用接受动态对象的1st函数。
有些问题非常接近这些,但没有一个能解决我的疑问。
堆栈溢出Q1堆栈溢出Q2堆栈溢出Q3
看起来设计应该像这个
public abstract partial class Class1<T> where T : Class1<T>, new()
{
protected abstract void Load(dynamic row);
private static T GetItem(dynamic row)
{
var item = new T();
if (row != null)
item.Load(row);
return item;
}
public static T GetDetails(long ID)
{
var row = Shared.SessionWrapper.Current.globaldbcon.QuerySingle("SELECT * FROM ["
+ EntityLayout.ContainerName + "].["
+ EntityLayout.TableName + "] WHERE ID=@0", ID);
return GetItem(row);
}
public static List<T> ListAll()
{
List<T> result = new List<T>();
foreach (var row in Shared.SessionWrapper.Current.globaldbcon.Query("SELECT * FROM ["
+ EntityLayout.ContainerName + "].["
+ EntityLayout.TableName + "]")) result.Add(GetItem(row));
return result;
}
}
以及示例实现
public class Class3 : Class1<Class3> {
{
// ...
protected override void Load(dynamic row)
{
// No need to check for null, it is enforced by the base class
ID = Convert.ToInt64(row.ID);
UID = Convert.ToInt64(row.UID);
// ...
}
}
基本上,您探索了.NET泛型类约束(T : Class1<T>
)支持的奇怪的重复模板模式,以确保派生类包含抽象的Load
方法,而new T()
部分由new()
约束强制执行。