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I have this structure
Customer - has many Orders - has many OrderItems I want to generate a list of CustomerItems via LINQ given a subset of OrderItems:
List of new { Customer, List<OrderItem> Items } which is a grouping of all the items a Customer has ordered from the subset of items
How can i use LINQ to back track through the order and group by Customer to generate this object?
so far I'm on something like
items .GroupBy(i => i, i => i.Order.Customer, (i, customer) => new {customer, i}) But thats obviously not a List. I'm guessing I need a SelectMany in there somewhere, but could do with some pointers.
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You can also use Into Group with GroupBy in VB.Net. LINQ query is ended with the help Select or Groupby clause. It can also support method syntax in both C# and VB.Net languages. As shown in example 2.
GroupBy() Method in C# The GroupBy() is an extension method that returns a group of elements from the given collection based on some key value. The following is our array − int[] arr = { 2, 30, 45, 60, 70 }; Now, we will use GroupBy() to group the elements smaller than 50 − arr.
Items select new { Sum(p. Total), Sum(p. Done)};
Count() methodIEnumerable<string> strings = new List<string> { "first", "then", "and then", "finally" }; // Will return 4 int result = strings. Count(); NOTE: The Count() LINQ method (an extension method to IEnumerable<T> ) is slightly different from the Count property on List<T> .
I think you want:
items.GroupBy(item => item.Order.Customer) .Select(group => new { Customer = group.Key, Items = group.ToList() }) .ToList() If you want to continue use the overload of GroupBy you are currently using, you can do:
items.GroupBy(item => item.Order.Customer, (key, group) => new { Customer = key, Items = group.ToList() }) .ToList() ...but I personally find that less clear.
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