CODEWITHSUNDEEP
c#
Rod
Rod

Reputation: 15475

can i use string.join in a generic list

Is there a way to take generic list and join a certain property into a comma-separated value?

public class Color
{
  public int Id {get; set;}
  public string Name{get; set;}
}

List<Color> list = new List<Color>();
Color c1 = new Color() { Id = 1, Name = "red" }
Color c2 = new Color() { Id = 2, Name = "blue" }

Can I do something like

list.Join(

to get

"red, blue";

Upvotes: 1

Views: 4122

Answers (4)

Richard Szalay
Richard Szalay

Reputation: 84784

Sure, as of .NET 4 String.Join has an overload for String.Join(string, IEnumerable<string>). You can even avoid calling ToString by using the String.Join(string, IEnumerable<T>) overload.

So these are both valid:

String.Join(",", new List<int> { 1, 2, 3 });
String.Join(",", new List<string> { "1", "2", "3" });

Upvotes: 0

unconnected
unconnected

Reputation: 1011

You can use String.Join for generics. But to get what you want you have to make some modifications to your code, otherwise you'll get something like this as result:

Namespace.Color, Namespace.Color

Option A as mrtig suggested:

String.Join(",", list.Select(x=>x.Name))

Option B, extend your class with ToString:

public class Color
{
  public int Id {get; set;}
  public string Name{get; set;}
  public string ToString(){
    return this.Name;
  }
}

Now you can use just:

String.Join(",",list) //where list is IEnumerable<Color>

Upvotes: 0

mrtig
mrtig

Reputation: 2267

No, you cannot. This method is defined as string.Join(String, String[]). There is a way to accomplish what you are trying to do: 

string.Join(",", list.Select(c=>c.Name).ToArray());

Upvotes: 5

Yeldar Kurmangaliyev
Yeldar Kurmangaliyev

Reputation: 34234

This extension Join stands for LINQ Join.

List<Color> list = new List<Color>();
list.Join(...)

If you want to concatenate a collection in a string, you need to use String.Join.
The following will result in the desired "red, blue" string:

String.Join(", ", list.Select(x => x.Name));

Upvotes: 2

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