Question

Say I’ve got 2 lists that look something like

      ID | IsChipCollected | IsShirtCollected | IsPackCollected
A     0                 1                  0                 1
      1                 0                  1                 0
      2                 0                  0                 1      


B     0                 0                  1                 0
      1                 0                  0                 1
      2                 1                  1                 1     

Basically I need to compare and merge the 2 lists and if a certain flag has been set to say true in B, i should select it instead of A

I know how to achieve this with a single column, but I’m struggling wrapping my head around doing it in a scenario with 2+ columns

  var result = A.Concat(B)
        .GroupBy(x => x.Id)
        .Select(g => g.OrderByDescending(x => x.IsShirtCollected).First())

I’ll update my code sample if i make any progress on this, (as I’m currently still hacking away :P)

Expected Result

     ID | IsChipCollected | IsShirtCollected | IsPackCollected
      0                 1                  1                 1
      1                 0                  1                 1
      2                 1                  1                 1      

Answer 1

var result = A.Concat(B)
        .GroupBy(x => x.Id)
        .Select(g => new {//or new <A and B's generic type>, then change the underCode with proper case
             id = g.Key,
             isShipCollected = g.Max(m => m.IsChipCollected),
             isShirtCollected = g.Max(m => m.IsShirtCollected),
             isPackCollected = g.Max(m => m.IsPackCollected)
    });

Edit

Following Servy’s (good) idea (changing 1 / 0 to boolean values)

var result = A.Concat(B)
       .GroupBy(x => x.Id)
       .Select(g => new { 
            id = g.Key,
            isShipCollected = g.Any(m => m.IsChipCollected == 1),
            isShirtCollected = g.Any(m => m.IsShirtCollected == 1),
            isPackCollected = g.Any(m => m.IsPackCollected == 1)
        });