conditional assignments in Linq to SQL methods

Question

How do I do something like the following, assinging new values based on condition within a linq method but keeping all results.

 int x= 100;

 var results= from r in Results where r.id==id select r
              { if r.value==x set r.result="Found"}

Answer 1

You're not really meant to - ideally queries shouldn't have side effects. I mean you can do:

var results = Results.Where(r => r.id == id)
                     .Select(r => { 
                          if (r.value == x)
                          {
                              r.result = "Found"; 
                          }
                          return r; 
                      };

I'd generally try not to though...

Note that this really won't work in LINQ to SQL etc.

Answer 2

Linq should not be used in that way. I would iterate over the results of the query and then change them.

 var results= from r in Results where r.id==id select r;

 foreach (var r in results.ToList()) { if (r.value==x) r.result="Found"; }

Answer 3

It's probably better to make a second pass so you can keep your query clean and side-effect-free.

int x = 100;

List<Result> results = (from r in Results
                        where r.id == id
                        select r).ToList();

results.ForEach(r => r.result = r.value == x ? "Found" : "Not Found");