Question

Assuming I had a collection like this..

var list = new List<Item>
{
 new Item
 { 
  Name = "Software",
  Price = 100
 },
 new Item
 {
  Name = "Software",
  Price = 200
 },
 new Item
 {
  Name = "Hardware",
  Price = 100
 }
};

And the ‘Names’ are not going to be known, I want to write a LINQ query that will return a list of everything with a matching name. I cannot use “Select”, because the names, again, are not known at design time.

Any ideas?

Answer 1

I’m not entirely sure whether you want to filter, or group the results.

If you want to filter, you can use Where with a runtime-supplied name:

string nameToFind = GetTheNameToFind(); // Can come from user, config, etc
var matches = list.Where(item => item.Name == nameToFind);

If you want to group by all of the names (ie: have 2 software + 1 hardware element), you could use Enumerable.GroupBy:

var groups = list.GroupBy(item => item.Name);

foreach(var group in groups)
{
    Console.WriteLine("Group {0}:", group.Key);
    foreach(var item in group)
         Console.WriteLine("    Item: {0} - {1}", item.Name, item.Price);
}