ObjectQuery<T> 相当于 Entity Framework 6

Question

使用 Entity Framework 4（旧版）我可以例如使用 ObjectQuery 查询：

// where Product is a table in a sample 
// database created with sql management studio
// Product table has a foreign key pType to another table p_type and there is a pType key there
// pType is of type int and another column that is called description which describes the pType
// 1 would be shoes 2 would be hats etc.
// filteredCombobox is data boung pType(displaymember) and Description(valuemember) 
// dbcontext is the database Entity

//this event below is the SelectionChangeCommit
        private void listToBeFiltered(object sender, EventArgs e)
{
    ObjectQuery<Product> itemsToBeFiltered = new ObjectQuery<Product>(
    "Select Value c FROM Product AS c WHERE c.pType = " + filterCombobox.SelectedValue, dbcontext);

    dataGridView1.DataSource = itemsToBeFiltered;
}

所以当我 select 组合框中的鞋子时，网格应该只显示鞋子 pType，它是带有鞋子描述的 1。

我想知道上面代码的 EF6 等价物是什么。卡了2个星期。任何帮助将不胜感激。谢谢朋友

Answer 1

虽然不推荐或标准方法，但您可以强制转换 DbContext 以获得 ObjectContext 并使用它：

using (var dbContext = new MyContext())
{
    var objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;
    var itemsToBeFiltered = objectContext.CreateQuery<Product>("sql here...", params);
}

编辑： 只是链接到 OP 的下一个问题：

ObjectQuery<T> 相当于 Entity Framework 6

ObjectQuery<T> equivalent in Entity Framework 6

c#

sql-server

linq-to-entities

entity-framework

visual-studio-2013