Ray*_*lli 5 c# linq lambda expression
首先,一点背景.我正在使用ASP.NET Web API和Entity Framework 5开发REST API,但是系统的要求是我的ApiControllers和我的DbContext之间存在多层逻辑.逻辑的这些层包括分离从我的DbContext实体,在内存应用组假想变为实体(一个过程.我打电话物化的改变一套),然后让用户检查系统应这些变化得到的新状态应用.实体的新状态不会立即保存到数据库中.相反,实现在Web服务器的内存中保存,用户可以检查当前数据或各种更改集的许多实现之一.
现在我的问题.
public interface IIdentifiable
{
long Id { get; set; }
}
public class Foo : IIdentifiable
{
public long Id { get; set; }
public string Name { get; set; }
public List<Bar> Bars { get; set; } // Navigation Property
}
public class Bar : IIdentifiable
{
public long Id { get; set; }
public string Name { get; set; }
public long FooId { get; set; } // Foreign Key Property
public Foo Foo { get; set; } // Navigation Property
}
public class Materialization
{
IEnumerable<Foo> Foos { get; set; }
IEnumerable<Bar> Bars { get; set; }
}
public interface IRepository<TItem> : IQueryable<TItem>, ICollection<TItem>, IDisposable
where TItem : class, IIdentifiable
{
IRepository<TItem> Include<TProperty>(Expression<Func<TItem, TProperty>> path);
// Other methods
}
public class MateriailizationRepository<TItem> : IRepository<TItem>
where TItem : class, IIdentifiable
{
private Materialization _materialization;
public MateriailizationRepository(Materialization materialization)
{
_materialization = materialization;
}
public IRepository<TItem> Include<TProperty>(Expression<Func<TItem, TProperty>> path)
{
// Populate navigation property indicated by "path"
}
// Other methods
}
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每个Bar都有一个外键属性,表明Foo它属于它,但是没有填充Bar.Foo和Foo.Bars导航属性,因为这会使实现过程复杂化.因此,物化后已完成,Materialization.Foos并Materialization.Bars包含由外键属性指的是对方,但没有导航属性对象的集合(即所有的导航属性的值都为空或空List<T>S).我希望能够在我的工作中做到以下几点ApiController.
public IQueryable<Foo> Get (bool includeBars = false)
{
Materialization materialization;
// Materialize
using (IRepository<Foo> repository = new MateriailizationRepository<Foo>(materialization))
{
IRepository<Foo> query = repository;
if (includeBars)
query = query.Include(f => f.Bars);
return query;
}
}
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MateriailizationRepository<Foo>我们的主要职责是获取物化Foo对象,但由于它具有对整个物体的引用,Materialization我希望能够根据需要包含物化Bar对象Materiailization.Bars.
我将如何实现MateriailizationRepository.Include()模仿IQueryable.Include()扩展方法?