Convert a list of objects to an array of one of the object's properties

Question

Say I have the following class:

public class ConfigItemType
{
    public string Name { get; set; }
    public double SomeOtherThing { get; set; }
}

and then I make a list of the following classes (List<ConfigItemType> MyList)

Now I have a method with the following signature:

void AggregateValues(string someUnrelatedValue, params string[] listGoesHere)

How can I fit MyList in to the listGoesHere using the value in ConfigItemType.Name as the params string array?

I am fairly sure that Linq can do this.... but MyList does not have a select method on it (which is what I would have used).

score 320 · Accepted Answer · answered Jan 21 '11 at 23:55

320

You are looking for

MyList.Select(x=>x.Name).ToArray();

Since Select is an Extension method make sure to add that namespace by adding a

using System.Linq

to your file - then it will show up with Intellisense.

answered Jan 21 '11 at 23:55

BrokenGlass

That is what I thought of as well. But Select does not show up in the intellisense. – Vaccano Jan 21 '11 at 23:58
1

GAAAAAAA! I was missing the linq include! – Vaccano Jan 21 '11 at 23:59
1

I am dumb! Ah well. Free rep for helping me figure it out. – Vaccano Jan 21 '11 at 23:59
1

you need to use using System.Data.Linq; then follow BrokenGlass answer – Rami Alshareef Jan 21 '11 at 23:59
fantastic solution. I wanted to access the String "id" in my Object-List. Worked perfect `List somestringlist = myobjectlist.Select(x => x.id).ToList();` – Marty_in_a_Box May 11 '16 at 15:24

score 21 · Answer 2 · answered Jan 21 '11 at 23:59

I am fairly sure that Linq can do this.... but MyList does not have a select method on it (which is what I would have used).

Yes, LINQ can do this. It's simply:

MyList.Select(x => x.Name).ToArray();

Most likely the issue is that you either don't have a reference to System.Core, or you are missing an using directive for System.Linq.

score 6 · Answer 3 · edited Jul 24 '15 at 06:19

6

For everyone who is stuck with .NET 2.0, like me, try the following way (applicable to the example in the OP):

ConfigItemList.ConvertAll<string>(delegate (ConfigItemType ci) 
{ 
   return ci.Name; 
}).ToArray();

where ConfigItemList is your list variable.

edited Jul 24 '15 at 06:19

Community

answered Jul 15 '14 at 11:44

Spyros

score 6 · Answer 4 · answered Jan 21 '11 at 23:57

6

This should also work:

AggregateValues("hello", MyList.ConvertAll(c => c.Name).ToArray())

answered Jan 21 '11 at 23:57

4 Answers4