对象查询 <T> 实体框架6中的等效项

Question

With Entity Framework 4 (Legacy) i would be able to query using ObjectQuery for example:

// 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;
}

so when i select shoes in combo box the grid should only show shoes pType which is a 1 with shoes description.

what i want to know what is the EF6 equivalent of the code above. been stuck for 2 weeks. any help would be greatly appreciated. Thanks friends

Answer 1

Though not recommended or the standard approach, you can cast the DbContext to get the ObjectContext and work with that:

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

EDIT: Just linking to the next question the OP had: Entity Framework 6 + C# passing a combobox.SelectedValue as a parameter for context.CreateQuery something simple i am missing?