如何使用UnitOfWork模式从添加中获取ID？ [英] How to get id from Add using UnitOfWork pattern?

问题描述

我正在使用UnitOfWork模式来抽象我的Asp.Net应用程序中的数据库访问。基本上，我遵循此处描述的UnitOfWork模式方法：

I am using the UnitOfWork pattern to abstract database access in my Asp.Net application. Basically I follow the UnitOfWork pattern approach described here:

https://chsakell.com/2015/02/15/asp-net-mvc-solution-architecture-best-practices/

但是，我很难理解如何获得新添加的商品的ID。就像我要向客户存储库中添加新客户一样，我将如何获取客户ID？问题是Add和Commit是分离的，并且在Commit之后才知道ID。

However, I'm struggling to understand, how I will get the Id of a newly added item. Like if I want to add a new customer to my Customer repository, how will I get the customer id? The problem is that Add and Commit are decoupled, and the Id is not known until after Commit.

有没有一种方法可以使用

Is there a way to get the id of an added item, using the UnitOfWork pattern?

推荐答案

请注意，我不希望我的EF模型类传播到我的域层

我已经解决了。我认为它很好用

I have done a workaround. I think it works pretty well

当您需要存储库时，例如 DbCars ，然后插入一个您想要获取仅在 SaveChanges（）时生成的 Id 的新 DomainCar 。

When you want a repository, for example of DbCars, and you insert a new DomainCar you want to get that Id that was only generated when SaveChanges() is applied.

public DomainCar //domain class used in my business layers
{
    public int Id{get;set;}
    public string Name{get;set;}
}

public DbCar //Car class to be used in the persistence layer
{
    public int Id{get;set;}
    public string Name{get;set;}
    public DateTime CreatedDate{get;set;}
    public string CreatedBy{get;set;}
}

首先创建通用 IEntity 接口和实现该接口的类：

First you create a generic IEntity interface and a class implementing it:

public interface IEntity<T>
{
    T Id { get; }
}

public class Entity<T> : IEntity<T>
{
    dynamic Item { get; }
    string PropertyName { get; }
    public Entity(dynamic element,string propertyName)
    {
        Item = element;
        PropertyName = propertyName;
    }
    public T Id
    {
        get
        {
            return (T)Item.GetType().GetProperty(PropertyName).GetValue(Item, null);
        }
    }
}

然后在添加方法中存储库中，您返回 Id 类型的 IEntity ：

Then in your add method of the repository you return a IEntity of the type of your Id:

public IEntity<int> AddCar(DomainCar car)
{
    var carDb=Mapper.Map<DbCar>(car);//automapper from DomainCar to Car (EF model class)
    var insertedItem=context.CARS.Add(carDb);
    return new Entity<int>(insertedItem,nameof(carDb.Id));
}

然后，在某处调用add方法和随之而来的Save（）的工作单位：

Then , somewhere you are calling the add method and the consequent Save() in the UnitofWork:

using (var unit = UnitOfWorkFactory.Create())
{
   IEntity<int> item =unit.CarsRepository.AddCar(new DomainCar ("Ferrari"));
   unit.Save(); //this will call internally to context.SaveChanges()
   int newId= item.Id; //you can extract the recently generated Id
}

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