C# endpoint giving back a nested list of directories and files as JSON

Question

My goal is to implement an endpoint which gives back a nested list of all files and directories starting from a certain root directory, e.g. C:\Temp. I have written the following code:

namespace API.Controllers
{
    public class UploadController : BaseController
    {
        [Route("api/Uploaded", Order = -1)]
        [ResponseType(typeof(IEnumerable<string[]>))] // <- this has to be adjusted, I guess.
        public IHttpActionResult AutoUpload()
        {
            string[] entries = Directory.GetFileSystemEntries("C:\Temp", "*", SearchOption.AllDirectories);
            // <-- Here should come some conversion to a nested JSON.
            return Ok(entries); 
        }
    }
}

When I am querying the endpoint, e.g. with curl -X POST --header 'Accept: application/json' 'http://localhost:63291/api/Uploaded' the response is something

[
 "C:\\\\Temp\\file1",
 "C:\\\\Temp\\dir1\\file2",
 "C:\\\\Temp\\dir1\\file3"
]

What I would rather like to have is something like the following

[
    { "~":
        [ "file1" ]
    },
    {
        "~/dir1":
                [
                     "file2" ,
                     "file3" 
               ]
    }
]

I am sure it cannot be so complicated to convert my list into a nested JSON, but I somehow do not manage to do it. I fear, I am missing the appropriate search terms. Please help!

Well, `Directory.GetFileSystemEntries` will return an array of all items that match your search pattern. To return nested you will need to iterate the path to correctly create your structure. You could potentially create an object with a parent and child directory to group on that you eventually flatten, but you will need to traverse and parse yourself to create the nested structure. — Greg, Nov 26 '19 at 17:43

score 2 · Accepted Answer · answered Nov 27 '19 at 16:12

First of all Attribute [ResponseType] does not affect your response, it's just metadata that is used by for example swagger to document your endpoints.

Directory.GetFileSystemEntries as Greg said returns collection (array) od strings representing paths. You need to parse your results to format you want i see that is something like File class and Directory containing File but better approach it would be to use build in types like FileInfo.

DirectoryInfo class provides some useful methods that you could use:

Get all files in directory: https://learn.microsoft.com/en-us/dotnet/api/system.io.directoryinfo.getfiles?view=netframework-4.8

Get all directories in directory: https://learn.microsoft.com/en-us/dotnet/api/system.io.directoryinfo.getdirectories?view=netframework-4.8

Or also get both: https://learn.microsoft.com/en-us/dotnet/api/system.io.directoryinfo.getfilesysteminfos?view=netframework-4.8

Read about data types returned by that methods and use the best of it ;)

I think you will need to do some recursion to go through all subdirectories.

C# endpoint giving back a nested list of directories and files as JSON

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