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Struggling with linq

I haven't got up to speed with linq and need quick fix please.
I have a flat table of bookings i.e. people at certain locations on certain dates.
I would like to use linq to convert into objects that are shown in the image: each instance of the BookingViewModel represents a date, and it has a date, a location and a collection of bookings.
How do I use linq to ?group the flat table by date and location, and then use the result to populate the collection property. All I seem to have access to is the "Key".

I've tried:
 var group =
                    bookingRepository.GetAll().GroupBy(b => b.fkDateTimeObjectId, b=>b.fkLocationId);
Linq-question.png
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quentinA
Asked:
quentinA
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2 Solutions
 
käµfm³d 👽Commented:
I think query syntax would be easier to swallow in this particular case, so...

var query = from booking in bookingRepository.GetAll()
            group booking by new { booking.Date, booking.Location } into g
            select new BookingViewModel()            
            {
            	Date = g.Key.Date,
            	Location = g.Key.Location,
            	Bookings = g.ToList(),
            };

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You create a new anonymous object with all of the properties that you will be grouping on. Then simply select a new instance of your view model class, and assign each property. The Key will have the two properties that you grouped on, so you can use that to assign those two particular fields.
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Fernando SotoRetiredCommented:
Hi quentinA;

If I understand the question correctly this should give you what you want.

var group = bookingRepository.GetAll()
                             .GroupBy(b => new { b.Date, b.Location})
                             .Select( g => new BookingViewModel() 
                             {
                             	    Date = g.Key.Date,
            	                    Location = g.Key.Location,
            	                    Bookings = g.Select(p => p.BookedPerson).ToList()
                             });

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quentinAAuthor Commented:
Thank you both.
Can you recommend a linq book/ training (or should I post this as another question?)
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Fernando SotoRetiredCommented:
Hi ;

I have used LinqPad which is a free software package for learning and testing Linq queries. The software is free to download and use. They also have a paid option which add autocompletion but only for C# NOT VB .Net.

The software contains many working examples in its library and the website also contains helpful information.

LinqPad

LINQPad standard edition is free to download and use. Autocompletion is an optional extra.
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quentinAAuthor Commented:
Thanks again! That's great.
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Fernando SotoRetiredCommented:
Not a problem.
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