Question

I have an Interface as below:

  public interface IRepository<T> where T : class
{

T is type of my entities.
In this interface I have some methods which will use Entity's Id property. So, How can I guarantee that, the Entity has Id property when some body wants to implement this interface?

Answer 1

救援的接口！

按如下方式定义界面：

// Why IEquatable<T>? Because you don't want identifiers that may not
// be able to prove that they're equal or not. Most commonly used 
// types used as identifiers already implement IEquatable<T>. For example: 
// int, Guid...
public interface ICanBeIdentifiable<TId> where TId : IEquatable<TId>
{
    TId Id { get; }
}

...并按如下方式更改存储库界面签名：

public interface IRepository<T> where T : class, ICanBeIdentifiable<Guid>
...

...或者如果您想完全打开任何标识符类型的大门：

   public interface IRepository<TId, T> 
            where TId : IEquatable<TId>
            where T : class, ICanBeIdentifiable<TId>

主要缺点是您的域对象必须实现全新的界面，但值得付出努力。

Answer 2

您可以添加其他界面，这将推动每个实体拥有Id属性

public interface IEntity
{
    int Id { get; set; }
}

public interface IRepository<T> where T : class, IEntity
{

}

How I can force an implemented Class to use an Entity which has a specific Parameter?

2 个答案: