Get nested list of dynamic objects to be displayed as tree

Question

I have these two classes

public class Category
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int? ParentId { get; set; }
}

public class CategoryVm
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<CategoryVm> SubCategories { get; set; }
}

and I have a list of the first class and I want to convert it to the second form to be displayed inside a tree view.

---

Example input

Example output

Answer 1

Here is the code that I used, and it worked properly

public List<CategoryVm> GetCategoriesTree(List<Category> categoriesList)
{
    var categoriesTree = categoriesList.Where(category => category.ParentCategoryId == null)
        .Select(category => new CategoryVm
        {
            Id = category.Id,
            Name = category.Name,
            SubCategories = new List<CategoryVm>()
        }).ToList();
    foreach (var category in categoriesTree)
    {
        FillSubCategories(category, categoriesList);
    }
    return categoriesTree;
}

private void FillSubCategories(CategoryVm categoryVm, List<Category> categoriesList)
{
    var subCategories = categoriesList.Where(category => category.ParentCategoryId == categoryVm.Id).ToList();
    if (subCategories.Any())
    {
        categoryVm.SubCategories = subCategories.Select(category => new CategoryVm
        {
            Id = category.Id,
            Name = category.Name,
            SubCategories = new List<CategoryVm>()
        }).ToList();
        foreach (var subCategory in categoryVm.SubCategories)
        {
            FillSubCategories(subCategory, categoriesList);
        }
    }
}