使用循环依赖和可加载列表实现WebAPI [英] Implementing WebAPI with circular dependencies and loadable lists

问题描述

如何在WebAPI中实现这样的智能GET？我有2个课程，我想从我的服务中获得。让我们来看看它的书店与书对象有关系。

  public class Book 
 {
 Guid id {get;组; } 
 string标题{get;组; } 
 Store Store {get;组; } 
} 
 
 public class Store 
 {
 Guid id {get;组; } 
 string标题{get;组; } 
 string所有者{get;组; } 
 IEnumerable< Book>书籍{get;组; $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 
 
 $ p 
 
 
我有后端与SQL服务器和EntityFramework适配器在代码。只有在我需要它之后，我应该怎么做才能返回书籍清单？ 
如你所见，我有循环依赖，这使得我的JSON序列化程序显示错误。我解决了：
  config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Serialize; 
 config.Formatters.JsonFormatter.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects; 
  
但序列化所有数据，我的回复是巨大的，这对我的Windows Phone应用程序不利。在某些情况下，我只需要Store对象，但在其他情况下，我需要Store与所有引用的书籍。
 
 
 
在控制器中，我使用[Queryable]属性来使用OData查询。 
 P.S.我不能创建更多的Web方法，如GetBooks，GetStore等。应该是一种方法。
 
 
 
如何解决我的问题？
解决方案
 
 
 
我如何解决我的问题？
 
 
不要从您的API操作方法返回Entities。 
 
 
 
相反，返回模型。
 
 
 
所以，而不是这样：
  public IEnumerable< Store> GetStores（）
 {
 using（var db = new MyDbContext（））
 {
 return db.Stores; 
} 
} 
  
做这样的事情：
  public IEnumerable&StoreModel> GetStores（）
 {
 using（var db = new MyDbContext（））
 {
 var entities = db.Stores; 
 return entities.Select（x => new StoreModel 
 {
 Id = x.Id，
 Title = x.Title，
 Owner = x.Owner， 
 Books = x.Books.Select（y => new BookModel 
 {
 Id = y.Id，
 Title = y.Title，
 StoreId = x .Id，
}），
}）; 
} 
} 
  
通过这样做，您可以消除循环依赖图。 不再引用商店，只有 StoreId 。
 
How it is possible to implement such "smart" GET in WebAPI? I have 2 classes that i want to get from my service. Let's say its book store which has relation to book objects.
public class Book
{
    Guid Id { get; set; }
    string Title { get; set; }
    Store Store { get; set; }
}

public class Store
{
    Guid Id { get; set; }
    string Title { get; set; }
    string Owner { get; set; }
    IEnumerable<Book> Books { get; set; }
}
I have backend with SQL server and EntityFramework adapter in code. How should I make to return the list of books only after I need it (call for it), like with OData? 
As you can see I have circular dependancies, which makes my JSON serializer to show errors.  I resolve it with:
config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling  = Newtonsoft.Json.ReferenceLoopHandling.Serialize; 
config.Formatters.JsonFormatter.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
but serialized all data and my response is HUGE, which is not good for my Windows Phone app. In some cases I need only Store object, but in other cases I need Store with all referenced books.

In controllers I user [Queryable] attribute to use OData queries.
P.S. I can't create more web-methods like GetBooks, GetStore and so on. It should be one method.

How could I resolve my problem?
解决方案

  
How could I resolve my problem?
Do not return Entities from your API action methods.

Instead, return models.

So instead of this:
public IEnumerable<Store> GetStores()
{
    using (var db = new MyDbContext())
    {
        return db.Stores;
    }
}
Do something like this:
public IEnumerable<StoreModel> GetStores()
{
    using (var db = new MyDbContext())
    {
        var entities = db.Stores;
        return entities.Select(x => new StoreModel
        {
            Id = x.Id,
            Title = x.Title,
            Owner = x.Owner,
            Books = x.Books.Select(y => new BookModel
            {
                Id = y.Id,
                Title = y.Title,
                StoreId = x.Id,
            }),
        });
    }
}
By doing it this way you eliminate the circular dependency graph. Book no longer references Store, only StoreId.

                        
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