Join collection of objects into comma-separated string

Question

In many places in our code we have collections of objects, from which we need to create a comma-separated list. The type of collection varies: it may be a DataTable from whi

Answer 1

For collections you can use this method as well, for example:

string.Join(", ", contactsCollection.Select(i => i.FirstName));

You can select any property that you want to seperate.

Answer 2

string strTest = "1,2,4,6";
string[] Nums = strTest.Split(',');
Console.Write(Nums.Aggregate<string>((first, second) => first + "," + second));
//OUTPUT:
//1,2,4,6

Answer 3

In .NET 4 you can just do string.Join(", ", table.Rows.Select(r => r["title"]))

Answer 4

I found string.Join and Lambda Select> helps to write minimum code.

        List<string> fruits = new List<string>();
        fruits.Add("Mango");
        fruits.Add("Banana");
        fruits.Add("Papaya");

        string commaSepFruits = string.Join(",", fruits.Select(f => "'" + f + "'"));
        Console.WriteLine(commaSepFruits);

        List<int> ids = new List<int>();
        ids.Add(1001);
        ids.Add(1002);
        ids.Add(1003);

        string commaSepIds = string.Join(",", ids);
        Console.WriteLine(commaSepIds);

        List<Customer> customers = new List<Customer>();
        customers.Add(new Customer { Id = 10001, Name = "John" });
        customers.Add(new Customer { Id = 10002, Name = "Robert" });
        customers.Add(new Customer { Id = 10002, Name = "Ryan" });

        string commaSepCustIds = string.Join(", ", customers.Select(cust => cust.Id));
        string commaSepCustNames = string.Join(", ", customers.Select(cust => "'" + cust.Name + "'"));

        Console.WriteLine(commaSepCustIds);
        Console.WriteLine(commaSepCustNames);

        Console.ReadLine();

Answer 5

I love Matt Howells answer in this post:

I had to make it into an extension:

public static string ToCsv<T>(this IEnumerable<T> things, Func<T, string> toStringMethod)

Usage: [ I am getting all the emails and turning them into a csv string for emails ]:

var list = Session.Find("from User u where u.IsActive = true").Cast<User>();

return list.ToCsv(i => i.Email);