如何在C＃中使用linq修改列表的某些元素？

Question

I have this class:

public class Document
{
    public string ID { get; set; }
    public string Type { get; set; }
    public bool Checked {get;set; }
}

I create a set of 10 elements using Enumerable.Repeat static method:

var list = Enumerable.Repeat<Document>(
            new Document
            {
                ID="1",
                Type ="someType"
                Checked = true
            }, 10).ToList<Document>();

These creates 10 Documents all with the same properties. I need that some of them, for instance, the first 5 elements of the list list have the Checked property to false .

How can I achieve it, using as possible linq ?

Answer 1

Note that your original sample has a bug because it's creating a 10 element List<Document> that only has 1 actual Document object. Here is a better way of doing it

Enumerable
  .Range(1, 10)
  .Select(i => 
    new Document() { 
      ID = "1",
      Type = "someType",
      Checked = i <= 5
    })
  .ToList();

EDIT

Changed the code to be simpler. My original response was to editing an already existing list for which the following can be done

list.Take(5).ForEach(x => { x.Checked = false });

Note that you may have to define a simple ForEach method for this operation. If you don't have one defined here is an example

static class Extensions { 
  internal static void ForEach<T>(this IEnumerable<T> e, Action<T> action) {
    foreach (var item in e) { 
      action(item); 
    }
  }
}

Answer 2

Alternate idea to accomplish what you're asking for (also populates your ID column with something other than "1") :

var list = Enumerable.Range(1, 10)
                     .Select(i => new Document
                     {
                         ID = i.ToString(),
                         Type = "someType",
                         Checked = (i > 5)
                     }).ToList();