Where is client evaluation needed?-CodePudding

I have a query which works fine in Linq to Objects in this fiddle:

var list = from order in orders
             join detail in details
             on order.id equals detail.order into od
             select new { order = order, details = od };

I tried applying the same query when the data is in a database (note I am mapping Linq to Sql manually):

public class dbContext: DbContext {
   public DbSet<Order> Orders { get; set; }
   public DbSet<Detail> Details { get; set; }
   protected override void OnConfiguring(DbContextOptionsBuilder oB) {
     oB.UseSqlServer("...connection string...");
   }
}

using (var db = new dbContext() {
  var list = from order in db.Orders
               join detail in db.Details
               on order.id equals detail.order into orderDetails
               select new { order = order, details = orderDetails };
}

The above gives:

could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to 'AsEnumerable', 'AsAsyncEnumerable', 'ToList', or 'ToListAsync'. See https://go.microsoft.com/fwlink/?linkid=2101038 for more information.

I tried details = orderDetails.ToList() in the last line but the same error is there. Where should I add the manual client evaluation?

Some background information: the following database query (without the into) works fine:

var list = from order in db.Orders
            join detail in db.Details
            on order.id equals detail.order
           select new { order = order, detail = detail };

CodePudding user response：

Instead of a join you should declare Navigation Properties and use something like:

var query = from order in db.Orders
  select new { order = order, details = order.OrderDetails };

var list = query.ToList();

or simply

var list = db.Orders.Include(o => o.OrderDetails).ToList();