Returning recursive result - asp.net-mvc

Question

I currently have this in a simple MVC Api controller:
var rootFolder = Umbraco.TypedMedia(200);
return rootFolder.Children().Select(s => new MediaItem
{
Name = s.Name,
Children = s.Children.Select(e => new MediaItem
{
Name = e.Name
})
});
It works, but only return level 1 and 2.
I tried using
return rootFolder.Descendants(), which returns all results from all levels - but "flattened out", so I cannot see the structure in the output.
The output is used in a simple app, navigating a tree structure.
Any ideas, as to how I can make it recursive?
Using Descendants, the output is returned like this
[
{
"Name":"dok1"
},
{
"Name":"dok2"
},
{
"Name":"dok21"
}
]
But it should be
[
{
"Name":"dok1"
},
{
"Name":"dok2"
"Children": [
{
"Name":"dok21"
}
]
}

Answer 1

Not sure you really need recursion here -- the solution below (or something similar) should suffice
// Dictionary between level/depth(int) and the files on that level/depth
var fileDictionary = new Dictionary<int, List<MediaItem>>();
var children = rootFolder.Children();
var depth = 1;
while (children.Any())
{
var tempList = new List<MediaItem>();
children.ForEach(child => {
tempList.Add(child);
});
fileDictionary.Add(depth, tempList);
children = children.Children();
depth++;
}
Then, you can do something like:
foreach (var key in fileDictionary.Keys)
{
// Access the key by key.Key (key would be "depth")
// Access the values by fileDictionary[key] (values would be list of MediaItem)
}

Answer 2

Why not just create a recursive function like so?
IEnumerable<MediaItem> ConvertToMediaItems(IEnumerable<IPublishedContent> items)
{
return items?.Select(i => new MediaItem
{
Name = i.Name,
Children = ConvertToMediaItems(i.Children)
}) ?? Enumerable.Empty<MediaItem>();
}
Then the usage would be
var rootFolder = Umbraco.TypedMedia(200);
return ConvertToMediaItems(rootFolder.Children());
You can also make the function a local function if it's only needed in one place.