Can we create a grouped list to normal list?-CodePudding

Here it is just an example. Suppose we have class Grouped (Items are gruoped by group name) as given below:

public class Grouped
{
  public int Id { get; set; }
  public string GroupName { get; set; }
  public List<Item> Items{ get; set; }
}

public class Item 
{ 
  public string ItemName { get; set; }
}

What i need to do is to make a list of Normal Class from the above Grouped Object using only linq c# but not using ForEach or ForLoop.

pubic class Normal
{
  public int Id { get; set;}
  public string GroupName { get; set;}
  public string ItemName { get; set;}
}

here is an example of list

Id	Name	Item
1	A	X
1	A	Y
2	B	Y
3	C	X
3	C	Y
3	C	Z

CodePudding user response：

If you have a collection of Grouped (and you should, based on the desired output, otherwise there is no source for multiple Ids) you can use SelectMany to flatten a nested collection. Something along this lines:

IEnumerable<Grouped> grouped = ...;
var result = grouped
    .SelectMany(g => g.Items.Select(i => new Normal
    {
        Id = g.Id,
        GroupName = g.GroupName,
        ItemName = i.ItemName
    }))
    .ToList();