Linq using sum() in list within a list

Question

The relationship between them is one order to many journals. Now I want to get the sum of all pending orders (or records that are flagged as false under IsDelivered in Order entity).

So far, I have this query but can't seem to get working when I add .Sum()

Orders .Where(o => o.IsDelivered == false) .Select(o => new { pendingOrders = o.Journals.Sum(j => j.TotalAmount) })

So far this results to:

In a nutshell, how can I get the sum of them? If query needs to be altered or should be a new one. It is welcome. Any help would be much appreciated. Thanks!

Sergey Kalinichenko · Accepted Answer · 2014-10-29 18:14:20Z

4

You can do it in several ways:

You could add Sum(n => n.pendingOrders) to the end of your query to add up the values, or
You could use SelectMany before Select, and use Sum instead of Select.

Either of the two approaches is going to work.

answered Oct 29, 2014 at 18:14

Sergey Kalinichenko

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BradleyDotNET · Accepted Answer · 2014-10-29 18:13:49Z

3

In this case, it is easiest to use SelectMany (MSDN) to flatten your collections, then use Sum:

Orders.Where(o => !o.IsDelivered).SelectMany(o => o.Journals).Sum(j => j.TotalAmount);

answered Oct 29, 2014 at 18:13

BradleyDotNET

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