Question

So I have built a recursive function that generates a collection of Category objects.

[ChildActionOnly]
public ActionResult FindAllCategorias()
{
    var categoriasDb = _categoriaRepository.FindAllCategorias().Where(s => s.CategoriaPadreId == null);
    List<CategoriaModel> model = new List<CategoriaModel>();

    foreach (var categoria in categoriasDb)
    {
            model.Add(new CategoriaModel()
                            {
                                CategoriaId = categoria.CategoriaId,
                                Nombre = categoria.Nombre,
                                Encabezado = categoria.Encabezado
                            });
    }

    foreach (var categoriaModel in model)
    {
        categoriaModel.Subcategorias = FindSubcategoriesForCategory(categoriaModel.CategoriaId);
    }

    return PartialView(model);
}

private List<CategoriaModel> FindSubcategoriesForCategory(int id)
{
    var subcategorias = _categoriaRepository.FindAllCategorias().Where(c => c.CategoriaPadreId == id);

    List<CategoriaModel> subcategoriasModel = new List<CategoriaModel>();

    foreach (var subcategoria in subcategorias)
    {
        subcategoriasModel.Add(new CategoriaModel()
                                    {
                                        CategoriaId = subcategoria.CategoriaId,
                                        Nombre = subcategoria.Nombre,
                                        Encabezado = subcategoria.Encabezado,
                                        Subcategorias = FindSubcategoriesForCategory(subcategoria.CategoriaId)
                                    });
    }

    return subcategoriasModel;
}

Now in my View, how do you suggestion I use recursion to spit out each Category in a template I choose? I’m not sure how to something like this in a View.

Answer 1

You could use a recursive display template:

@model List<CategoriaModel>
<ul>
    @Html.DisplayForModel()
</ul>

and then define a custom display template for a category (~/Views/Shared/DisplayTemplates/CategoriaModel.cshtml):

@model CategoriaModel
<li>
    @Html.DisplayFor(x => x.Encabezado) ... and something else about the category  
    <ul>
       @Html.DisplayFor(x => x.Subcategorias)
    </ul>
</li>

You may also find the following post useful in terms of optimizing your code and data access.