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Halil İbrahim Kalkan
7 years ago
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12 changed files with 540 additions and 34 deletions
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## Application Services |
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## 应用服务 |
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应用服务实现应用程序的**用例**, 将**领域层逻辑公开给表示层**. |
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从表示层(可选)调用应用服务,**DTO (数据传对象)** 作为参数. 返回(可选)DTO给表示层. |
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## 示例 |
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### 图书实体 |
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假设你有一个`Book`实体(聚合根), 如下所示: |
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````csharp |
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public class Book : AggregateRoot<Guid> |
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{ |
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public const int MaxNameLength = 128; |
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public virtual string Name { get; protected set; } |
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public virtual BookType Type { get; set; } |
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public virtual float? Price { get; set; } |
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protected Book() |
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{ |
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} |
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public Book(Guid id, [NotNull] string name, BookType type, float? price = 0) |
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{ |
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Id = id; |
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Name = CheckName(name); |
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Type = type; |
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Price = price; |
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} |
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public virtual void ChangeName([NotNull] string name) |
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{ |
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Name = CheckName(name); |
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} |
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private static string CheckName(string name) |
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{ |
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if (string.IsNullOrWhiteSpace(name)) |
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{ |
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throw new ArgumentException($"name can not be empty or white space!"); |
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} |
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if (name.Length > MaxNameLength) |
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{ |
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throw new ArgumentException($"name can not be longer than {MaxNameLength} chars!"); |
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} |
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return name; |
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} |
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} |
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```` |
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* `Book`实体中定义`MaxNameLength`限制`Name`属性的最大长度. |
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* `Book`构造函数与`ChangeName`确保`Name`属性值的有效性. 请注意, `Name`的setter不是`public`. |
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ABP不会强制开发者这样设计实体, 可以将所有的属性设置Public set/get. 由你来决定是否全面实施DDD. |
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### IBookAppService接口 |
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在ABP中应用程序服务应该实现`IApplicationService接口`. 推荐每个应用程序服务创建一个接口: |
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````csharp |
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public interface IBookAppService : IApplicationService |
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{ |
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Task CreateAsync(CreateBookDto input); |
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} |
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```` |
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我们将实现Create方法作为示例. CreateBookDto定义如下: |
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```csharp |
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public class CreateBookDto |
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{ |
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[Required] |
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[StringLength(Book.MaxNameLength)] |
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public string Name { get; set; } |
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public BookType Type { get; set; } |
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public float? Price { get; set; } |
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} |
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``` |
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有关DTO更的教程,请参见[数据传输对象文档](Entities.md) |
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### BookAppService(实现) |
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````csharp |
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public class BookAppService : ApplicationService, IBookAppService |
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{ |
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private readonly IRepository<Book, Guid> _bookRepository; |
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public BookAppService(IRepository<Book, Guid> bookRepository) |
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{ |
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_bookRepository = bookRepository; |
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} |
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public async Task CreateAsync(CreateBookDto input) |
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{ |
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var book = new Book( |
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GuidGenerator.Create(), |
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input.Name, |
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input.Type, |
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input.Price |
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); |
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await _bookRepository.InsertAsync(book); |
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} |
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} |
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```` |
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* `BookAppService`继承了基类`ApplicationService`· 这不是必需的, 但是`ApplicationService`提供了应用服务常见的需求(比如本示例服务中使用的`GuidGenerator`). 如果不继承它, 我们需要在服务中手动注入`IGuidGenerator`(参见[Guid生成](Guid-Generation.md)文档) |
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* `BookAppService`按照预期实现了`IBookAppService` |
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* `BookAppService` 注入了 `IRepository<Book, Guid>`(请参见[仓储](Repositories.md))在CreateAsync方法内部使用仓储将新实体插入数据库. |
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* `CreateAsync`使用`Book`实体的构造函数从给定的Input值创建新的`Book`对象 |
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### 数据传输对象 |
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应用服务使用并返回DTO而不是实体. ABP不会强制执行此规则. 但是将实体暴露给表示层(或远程客户端)存在重大问题, 所以不建议返回实体. |
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有关更多信息, 请参见[DTO文档](Entities.md). |
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### 对象到对象映射 |
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`CreateBook`方法使用参数`CreateBookDto`对象手动创建`Book`实体. 因为`Book`实体的构造函数强制执行(我们是这样设计的). |
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但是在很多情况下使用**自动对象映射**从相似对象设置对象的属性更加方便实用. ABP提供了一个[对象到对象映射](Object-To-Object-Mapping.md)基础设施,使其变得更加容易. |
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让我们创建另一种获取`Book`的方法. 首先,在`IBookAppService`接口中定义方法: |
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````csharp |
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public interface IBookAppService : IApplicationService |
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{ |
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Task CreateAsync(CreateBookDto input); |
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Task<BookDto> GetAsync(Guid id); //New method |
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} |
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```` |
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`BookDto`是一个简单的[DTO](Data-Transfer-Objects.md)类, 定义如下: |
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````csharp |
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[AutoMapFrom(typeof(Book))] //Defines the mapping |
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public class BookDto |
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{ |
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public Guid Id { get; set; } |
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public string Name { get; set; } |
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public BookType Type { get; set; } |
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public float? Price { get; set; } |
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} |
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```` |
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* `BookDto`定义了`[AutoMapFrom(typeof(Book))]`属性来从创建对象映射Book到BookDto. |
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然后你可以实现`GetAsync`方法. 如下所示: |
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````csharp |
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public async Task<BookDto> GetAsync(Guid id) |
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{ |
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var book = await _bookRepository.GetAsync(id); |
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return book.MapTo<BookDto>(); |
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} |
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```` |
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`MapTo`扩展方法通过复制具有相同命名的所有属性将`Book`对象转换为`BookDto`对象. |
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`MapTo`的另一种替代方法是使用`IObjectMapper`服务: |
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````csharp |
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public async Task<BookDto> GetAsync(Guid id) |
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{ |
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var book = await _bookRepository.GetAsync(id); |
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return ObjectMapper.Map<Book, BookDto>(book); |
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} |
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```` |
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虽然第二种语法编写起来有点困难,但是如果你编写单元测试,它会更好地工作. |
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有关更多信息,请参阅[对象到对象映射](Object-To-Object-Mapping)文档. |
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### 验证 |
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自动验证应用服务方法的输入(如ASP.NET Core 控制器的actions). 你可以使用标准数据注释属性或自定义验证方法来执行验证. ABP还确保输入不为空. |
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请参阅[验证](Validation.md)文档了解更多信息. |
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### 授权 |
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可以对应用程序服务方法使用声明性和命令式授权. |
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请参阅[授权](Authorization.md)文档了解更多信息. |
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### CRUD应用服务 |
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如果需要创建具有Create,Update,Delete和Get方法的简单CRUD应用服务,则可以使用ABP的基类轻松构建服务. 你可以继承CrudAppService或 AsyncCrudAppService. |
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示例: |
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创建继承`IAsyncCrudAppService`接口的`IBookAppService`接口. |
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````csharp |
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public interface IBookAppService : |
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IAsyncCrudAppService< //Defines CRUD methods |
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BookDto, //Used to show books |
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Guid, //Primary key of the book entity |
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PagedAndSortedResultRequestDto, //Used for paging/sorting on getting a list of books |
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CreateUpdateBookDto, //Used to create a new book |
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CreateUpdateBookDto> //Used to update a book |
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{ |
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} |
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```` |
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* IAsyncCrudAppService有泛型参数来获取实体的主键类型和CRUD操作的DTO类型(它不获取实体类型,因为实体类型未向客户端公开使用此接口). |
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`IAsyncCrudAppService`声明以下方法: |
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````csharp |
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public interface IAsyncCrudAppService< |
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TEntityDto, |
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in TKey, |
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in TGetListInput, |
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in TCreateInput, |
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in TUpdateInput> |
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: IApplicationService |
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where TEntityDto : IEntityDto<TKey> |
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{ |
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Task<TEntityDto> GetAsync(TKey id); |
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Task<PagedResultDto<TEntityDto>> GetListAsync(TGetListInput input); |
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Task<TEntityDto> CreateAsync(TCreateInput input); |
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Task<TEntityDto> UpdateAsync(TKey id, TUpdateInput input); |
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Task DeleteAsync(TKey id); |
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} |
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```` |
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示例中使用的DTO类是`BookDto`和`CreateUpdateBookDto`: |
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````csharp |
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[AutoMapFrom(typeof(Book))] |
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public class BookDto : AuditedEntityDto<Guid> |
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{ |
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public string Name { get; set; } |
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public BookType Type { get; set; } |
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public float Price { get; set; } |
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} |
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[AutoMapTo(typeof(Book))] |
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public class CreateUpdateBookDto |
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{ |
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[Required] |
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[StringLength(128)] |
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public string Name { get; set; } |
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[Required] |
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public BookType Type { get; set; } = BookType.Undefined; |
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[Required] |
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public float Price { get; set; } |
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} |
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```` |
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* `CreateUpdateBookDto`由创建和更新操作共享,但你也可以使用单独的DTO类. |
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最后`BookAppService`实现非常简单: |
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````csharp |
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public class BookAppService : |
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AsyncCrudAppService<Book, BookDto, Guid, PagedAndSortedResultRequestDto, |
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CreateUpdateBookDto, CreateUpdateBookDto>, |
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IBookAppService |
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{ |
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public BookAppService(IRepository<Book, Guid> repository) |
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: base(repository) |
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{ |
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} |
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} |
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```` |
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`AsyncCrudAppService`实现了`IAsyncCrudAppService`接口中声明的所有方法. 然后,你可以添加自己的自定义方法或覆盖和自定义实现. |
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### 生命周期 |
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应用服务的生命周期是[transient](Dependency-Injection)的，它们会自动注册到依赖注入系统. |
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TODO |
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