c# - 如何查询所有实现接口(interface)的表

Question

我已经为我的一些实体类实现了一个接口(interface):

public partial class Order : IReportable
{
   public string TableName { get { return "Order"; } }
}

public partial class Client: IReportable
{
 public string TableName { get { return "Client"; } }
}


public interface IReportable
{
    string TableName { get; }
}

然后我将其添加到 DbContext:

public virtual DbSet<IReportable> IReportable { get; set; }

当我尝试查询实现此接口(interface)的所有表时(如此处所示):

var result = from reportabletable in db.IReportable
             where reportabletable.TableName == table_name
            select reportabletable

我得到以下异常:

The type 'Report.DataAccess.IReportable' was not mapped. Check that the type has not been explicitly excluded by using the Ignore method or NotMappedAttribute data annotation. Verify that the type was defined as a class, is not primitive or generic, and does not inherit from EntityObject.

Answer 1

我会选择这样的东西:

创建这个扩展方法

public static class DbContextExtensions
{
    public static IEnumerable<T> SetOf<T>(this DbContext dbContext) where T : class
    {
        return dbContext.GetType().Assembly.GetTypes()
            .Where(type => typeof(T).IsAssignableFrom(type) && !type.IsInterface)
            .SelectMany(t => Enumerable.Cast<T>(dbContext.Set(t)));
    }
}

然后像这样使用它:

using (var db = new dbEntities())
{
 var result = from reportabletable in db.SetOf<IReportable>()
         where reportabletable.TableName == table_name
        select reportabletable
}