如何铸造DbSet< T>到列表< T> [英] How to cast DbSet<T> to List<T>

问题描述

给定以下简化的Entity Framework 6上下文，我试图填充一个列表与实体，但有如何通过反射铸造（我相信）的问题。

Given the following simplified Entity Framework 6 context, I am trying to populate a List with the entities but having problems with how to cast (I believe) via reflection.

public class FooContext : DbContext
{
   public virtual IDbSet<FooClass> Foo { get; set; }    
   //...
}

public class FooClass
{
    public int Id{ get; set; }
    public string Name {get; set; }
    //...    
}

public main()
{
     using (var context = new FooContext())
     {
         var sets = typeof(FooContext).GetProperties().Where(pi => pi.PropertyType.IsInterface && pi.PropertyType.GetGenericTypeDefinition().ToString().ToLower().Contains("idbset"));

         foreach (var set in sets)
         {
             //When I debug and enumerate over 'value' the entire results are shown so I believe the reflection part is OK.
             var value = set.GetValue(context, null);

             //Always returns null. How can I cast DbSet<T> to List<object> or List<T>? 
             var list = value as List<object>();

             //...
         }
     }
}

我这样做的实用程序方法进行一些集成测试我在做。我试图这样做而不使用直接内联SQL调用（使用SqlConnection和SqlCommand等）来访问数据库（因为数据存储可能会更改为Oracle等）。

I'm doing this for utility method for some integration testing I am doing. I am trying to do this without using direct inline SQL calls (using SqlConnection and SqlCommand etc) to access the database (as the datastore may change to Oracle etc).

推荐答案

IDBSet继承自 IQueryable< TEntity> ， IEnumerable< TEntity> ， IQueryable 和 IEnumerable ，因此您不能直接将其强制转换为列表。
你可以得到 DBSet 中所有实体的 List $ c> .ToList（）或 .ToListAsync（）

IDBSet inherits from IQueryable<TEntity>, IEnumerable<TEntity>, IQueryable, and IEnumerable, so you can't directly cast it to a list that way. You could get a List<TEntity> of all entities in the DBSet though by using .ToList() or .ToListAsync()

所有实体在内存中的副本，所以你应该考虑直接在DBSet上使用LINQ

THis creates a copy of all entities in memory though, so you should consider operating with LINQ directly on the DBSet

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