c# - 如何在 ASP.NET MVC 中组织 DAL

Question

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Answer 1

这是我的看法:

Should I create instances of repository for every entity in database or for all or one genereal instance, for example PostRepository can include entities like Post, Comment and Tag?

拥有一个单一的通用存储库将为您省去很多维护难题。您可以实现单个通用存储库，例如:

/// <summary>
/// This interface provides an abstraction for accessing a data source.
/// </summary>
public interface IDataContext : IDisposable
{
    IQueryable<T> Query<T>() where T : class;

    T Add<T>(T item) where T : class;

    int Update<T>(T item) where T : class;

    void Delete<T>(T item) where T : class;

    /// <summary>
    /// Allow repositories to control when SaveChanges() is called
    /// </summary>
    int SaveChanges();
}

并在单个上下文类中实现上述接口(interface)。

有些人也实现单独的特定存储库。

In controller I have to get some data, transform in into ViewModel and pass it into view. Where is the best place to do this? Services, Controller or something else?

在可从 DA、服务和 Web 访问的单独程序集中定义所有模型(DTO 或实体或 POCO)类。服务方法返回模型实例， Controller 将它们转换为 View 模型(使用 AutoMapper)并传递给 View 。同样在post method controller中，先将VM转化为Model，然后传给Service层进行持久化或处理。

If it is Service. How many services should I create? Also for every entity and pass into Controller 3 or 4 services if it is necessery? Or maybe do it like I wanted to do it in repository? (Create one common service which would contain some count of repositories. PostService, with repositories like PostRepository, CommentRepository and TagRepository)

我强烈建议您非常具体地定义服务。使用单一职责原则来定义您的服务。每个服务都应该提供相关的功能集。例如。 AuthService 将对不向他们发送电子邮件的用户进行身份验证，即 EmailService 工作。

我建议的模式非常适合不同的服务。例如:

public class DriverSearchService : IDriverSearchService
{
    private readonly IBlobService _blobService;
    private readonly IDataContext _dataContext;

    public DriverSearchService(IDataContext dataContext, IBlobService blobService)
     {
         _blobService = blobService;
        _dataContext = dataContext;
     }

    public void SaveDriveSearch(int searchId)
    {
        // Fetch values from temp store and clear temp store
        var item = context.Query<SearchTempStore>().Single(s => s.SearchId == searchId);

        // Temp object is latest so update the main store
        var mainSearch = context.Query<Search>().Single(s => s.Id == searchId);
        mainSearch.LastExecutedOn = DateTime.UtcNow;
        mainSearch.DataAsBlob = item.DataAsBlob;
        context.Update(mainSearch);
    }
}