APP
第 4 章 資源操作
4.1 項目創建
從本章起，我們將創建一個在線圖書館項目，通過這個 Web API 應用程序來實際地熟悉并掌握如何使用 ASP.NET Core 創建 RESTful API 應用
這個項目由兩個實體，作者和圖書組成，我們將使用數據傳輸對象（DTO）來表示這兩種資源
新建一個 ASP.NET Core 項目 Library.API，項目模板選擇 API
創建兩個 DTO
namespace Library.API.Models
{
public class AuthorDto
{
public Guid Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public string Email { get; set; }
}
}
namespace Library.API.Models
{
public class BookDto
{
public Guid Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public int Pages { get; set; }
public Guid AuthorId { get; set; }
}
}
4.2 使用內存數據
創建內存數據源 LibraryMockData，專門用于提供模擬數據
namespace Library.API.Data
{
public class LibraryMockData
{
// 獲取 LibraryMockData 實例
public static LibraryMockData Current { get; } = new LibraryMockData();
public List<AuthorDto> Authors { get; set; }
public List<BookDto> Books { get; set; }
public LibraryMockData()
{
var authorId1 = Guid.NewGuid();
var authorId2 = Guid.NewGuid();
Authors = new List<AuthorDto>
{
new AuthorDto
{
Id = authorId1,
Name = "Author 1",
Age = 46,
Email = "Author.com",
},
new AuthorDto
{
Id = authorId2,
Name = "Author 2",
Age = 38,
Email = "Author2.com",
}
};
Books = new List<BookDto>
{
new BookDto
{
Id = Guid.NewGuid(),
Title = "Book 1",
Description = "Description of Book 1",
Pages = 281,
AuthorId = authorId1,
}, new BookDto
{
Id = Guid.NewGuid(),
Title = "Book 2",
Description = "Description of Book 2",
Pages = 370,
AuthorId = authorId2,
}
};
}
}
}
接下來，我們使用倉儲模式來訪問 LibraryMockData 類中的數據
倉儲模式作為領域動態設計（DDD）的一部分，用于解耦業務邏輯層與數據訪問層
實現倉儲模式的方法有許多種，最簡單的一種是對每一個與數據庫交互的業務對象創建一個倉儲接口以及實現，還有一種就是創建一個通用的倉儲接口，所有其他倉儲接口都繼承這個接口，下面的例子就是通用的倉儲接口
namespace Library.API.Services
{
public interface IRepositoryBase<T>
{
IEnumerable<T> FindAll();
IEnumerable<T> FindByCondition(Expression<Func<T, bool>> expression);
void Create(T entity);
void Update(T entity);
void Delete(T entity);
void Save();
}
}
本章使用第一種方法來實現倉儲模式，創建倉儲接口
namespace Library.API.Services
{
public interface IAuthorRepository
{
IEnumerable<AuthorDto> GetAuthors();
AuthorDto GetAuthor(Guid authorId);
bool IsAuthorExists(Guid authorId);
}
}
namespace Library.API.Services
{
public interface IBookRepository
{
IEnumerable<BookDto> GetBooksForAuthor(Guid authorId);
BookDto GetBookForAuthor(Guid authorId, Guid bookId);
}
}
接下來創建接口的具體倉儲實現
namespace Library.API.Services
{
public class AuthorMockRepository : IAuthorRepository
{
public IEnumerable<AuthorDto> GetAuthors()
{
return LibraryMockData.Current.Authors;
}
public AuthorDto GetAuthor(Guid authorId)
{
var author = LibraryMockData.Current.Authors.FirstOrDefault(au => au.Id == authorId);
return author;
}
public bool IsAuthorExists(Guid authorId)
{
return LibraryMockData.Current.Authors.Any(au => au.Id == authorId);
}
}
}
namespace Library.API.Services
{
public class BookMockRepository : IBookRepository
{
public IEnumerable<BookDto> GetBooksForAuthor(Guid authorId)
{
return LibraryMockData.Current.Books.Where(b => b.AuthorId == authorId).ToList();
}
public BookDto GetBookForAuthor(Guid authorId, Guid bookId)
{
return LibraryMockData.Current.Books.FirstOrDefault(b => b.AuthorId == authorId && b.Id == bookId);
}
}
}
為了在程序中使用上述兩個倉儲接口，還需要在 ConfigureServices 方法中注入
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers();
services.AddScoped<IAuthorRepository, AuthorMockRepository>();
services.AddScoped<IBookRepository, BookMockRepository>();
}
4.3 創建控制器
首先從依賴注入容器中獲取之前定義的倉儲接口
namespace Library.API.Controllers
{
[Route("api/authors")]
[ApiController]
public class AuthorController : ControllerBase
{
public IAuthorRepository AuthorRepository { get; }
public AuthorController(IAuthorRepository authorRepository)
{
AuthorRepository = authorRepository;
}
}
}
4.4 獲取資源
獲取集合
[HttpGet]
public ActionResult<List<AuthorDto>> GetAuthors()
{
return AuthorRepository.GetAuthors().ToList();
}
獲取單個資源
[HttpGet("{authorId}")]
public ActionResult<AuthorDto> GetAuthor(Guid authorId)
{
var author = AuthorRepository.GetAuthor(authorId);
if (author == null)
{
return NotFound();
}
else
{
return author;
}
}
獲取父/子形式資源
namespace Library.API.Controllers
{
[Route("api/authors/{authorId}/books")]
[ApiController]
public class BookController : ControllerBase
{
public IAuthorRepository AuthorRepository { get; }
public IBookRepository BookRepository { get; }
public BookController(IAuthorRepository authorRepository, IBookRepository bookRepository)
{
AuthorRepository = authorRepository;
BookRepository = bookRepository;
}
[HttpGet]
public ActionResult<List<BookDto>> GetBooks(Guid authorId)
{
if (!AuthorRepository.IsAuthorExists(authorId))
{
return NotFound();
}
return BookRepository.GetBooksForAuthor(authorId).ToList();
}
}
}
獲取某一個具體的子級資源
[HttpGet("{bookId}")]
public ActionResult<BookDto> GetBook(Guid authorId, Guid bookId)
{
if (!AuthorRepository.IsAuthorExists(authorId))
{
return NotFound();
}
var targetBook = BookRepository.GetBookForAuthor(authorId, bookId);
if (targetBook == null)
{
return NotFound();
}
return targetBook;
}
本文摘自 ：https://blog.51cto.com/u
