Repositories, in practice, are used to perform database operations for domain objects (see [Entities](Entities.md)). Generally, a separated repository is used for each **aggregate root** or entity.
ABP can provide a **default generic repository** for each aggregate root or entity. You can [inject](Dependency-Injection.md) `IRepository<TEntity, TKey>` into your service and perform standard **CRUD** operations. Example usage:
> The example above uses hand-made mapping between [entities](Entities.md) and [DTO](Data-Transfer-Objects.md)s. See [object to object mapping document](Object-To-Object-Mapping.md) for an automatic way of mapping.
If your entity does not have an Id primary key (it may have a composite primary key for instance) then you cannot use the `IRepository<TEntity, TKey>` defined above. In that case, you can inject and use `IRepository<TEntity>` for your entity.
> `IRepository<TEntity>`has a few missing methods those normally works with the `Id` property of an entity. Because of the entity has no `Id` property in that case, these methods are not available. One example is the `Get` method that gets an id and returns the entity with given id. However, you can still use `IQueryable<TEntity>` features to query entities by standard LINQ methods.
Standard `IRepository<TEntity, TKey>` interface extends standard `IQueryable<TEntity>` and you can freely query using standard LINQ methods. However, some ORM providers or database systems may not support standard `IQueryable` interface.
ABP provides `IBasicRepository<TEntity, TPrimaryKey>` and `IBasicRepository<TEntity>` interfaces to support such scenarios. You can extend these interfaces (and optionally derive from `BasicRepositoryBase`) to create custom repositories for your entities.
Depending on `IBasicRepository` but not depending on `IRepository` has an advantage to make possible to work with all data sources even if they don't support `IQueryable`. But major vendors, like Entity Framework, NHibernate or MongoDb already support`IQueryable`.
So, working with `IRepository` is the **suggested** way for typical applications. But reusable module developers may consider `IBasicRepository` to support a wider range of data sources.
Default generic repositories will be sufficient for most cases. However, you may need to create a custom repository class for your entity.
对于大多数情况, 默认通用仓储就足够了. 但是, 你可能会需要为实体创建自定义仓储类.
#### Custom Repository Example
#### 自定义仓储示例
ABP does not force you to implement any interface or inherit from any base class for a repository. It can be just a simple POCO class. However, it's suggested to inherit existing repository interface and classes to make your work easier and get the standard methods out of the box.
public class PersonRepository : EfCoreRepository<MyDbContext,Person,Guid>, IPersonRepository
@ -113,5 +113,4 @@ public class PersonRepository : EfCoreRepository<MyDbContext, Person, Guid>, IPe
}
````
You can directly access the data access provider (`DbContext` in this case) to perform operations. See [entity framework integration document](Entity-Framework-Core.md) for more about custom repositories based on EF Core.
梁士伟
7 years ago