Question

Please find the table structure below:

Folderid                    parentFolderid              Guid
1                           0                           1234
2                           1                           5678
3                           2                           9012
4                           3                           87697
5                           7                           4443 

The requirement is if I pass folderId the function has to give me all the guids.

For example:If I pass 1 to the function, I should get first four Guids(parent and its children).
I have a function which returns all the guids as follows:

public List<Guid> Folders(int folderId)
{ 
    // To get the folderids based on parentfolderid
    var a = entity.Where(x => x.parentfolderId == folderId).FirstOrDefault();
     return a;

}

I am able to get only up to one level of ids.

Is there any way to get parent, its children, grandchildren till the leaf?

Answer 1

If you are able to get that table to a class, check this out:

public class Entity
{
    public int ID { get; set; }
    public int ParentID { get; set; }
    public string Name { get; set; }

    public static List<Entity> GetTree(int ID, List<Entity> ListToSearch, bool First = true)
    {
        List<Entity> FilteredEntities = new List<Entity>();

        FilteredEntities.AddRange(ListToSearch.Where<Entity>(x => x.ParentID == ID).ToList<Entity>());

        List<Entity> Temp = new List<Entity>();
        foreach (Entity current in FilteredEntities)
        {
            Temp.AddRange(GetTree(current.ID, ListToSearch, false));
        }

        FilteredEntities.AddRange(Temp);

        if (First)
        {
            FilteredEntities.Add(ListToSearch.Where<Entity>(x => x.ID == ID).Single<Entity>());
        }

        return FilteredEntities;
    }
}

Usage:

    List<Entity> filteredEntities = Entity.GetTree(1, entities);
    List<string> onlyTheNames = filteredEntities.Select<Entity, string>(x => x.Name).ToList<string>();

Regards