c# - LINQ to Entities 无法识别该方法

Question

public IQueryable<Product> GetModelsInBrand(int BrandId) 
{ 
    IQueryable<Product> query = 
         from Product 
          in ObjectContext.Products.Where(p => (p.BrandId == BrandId)) 
         orderby Product.Model 
         select Product; 
        query = query.Distinct(new ProductByModelEqualityComparer()); 
        return query; 
}

执行返回查询后，我得到

Load operation failed for query 'GetModelsInBrand'. LINQ to Entities does not recognize the method."

谁能帮忙修改一下吗？

Answer 1

LINQ-to-entities 可能不支持您在 ProductByModelEqualityComparer 中编写的代码。您可以在调用 Distinct 之前调用 AsEnumerable，这将使 Distinct 通过 linq-to-objects 执行，但它不会是 IQueryable 不再:

var enumerable = query.AsEnumerable().Distinct(new ProductByModelEqualityComparer()); return query; }