Add endpoint for retrieving "folder" media types. (#16345)

* Add endpoint for retrieving "folder" media types.

* The system Folder media type should always be considered a "folder"

src/Umbraco.Cms.Api.Management/Controllers/MediaType/Item/FolderMediaTypeItemController.cs

@@ -0,0 +1,37 @@
+using Asp.Versioning;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Umbraco.Cms.Api.Management.ViewModels.MediaType.Item;
+using Umbraco.Cms.Core.Mapping;
+using Umbraco.Cms.Core.Models;
+using Umbraco.Cms.Core.Services.ContentTypeEditing;
+
+namespace Umbraco.Cms.Api.Management.Controllers.MediaType.Item;
+
+[ApiVersion("1.0")]
+public class FolderMediaTypeItemController : MediaTypeItemControllerBase
+{
+    private readonly IMediaTypeEditingService _mediaTypeEditingService;
+    private readonly IUmbracoMapper _mapper;
+
+    public FolderMediaTypeItemController(IMediaTypeEditingService mediaTypeEditingService, IUmbracoMapper mapper)
+    {
+        _mediaTypeEditingService = mediaTypeEditingService;
+        _mapper = mapper;
+    }
+
+    [HttpGet("folders")]
+    [MapToApiVersion("1.0")]
+    [ProducesResponseType(typeof(PagedModel<MediaTypeItemResponseModel>), StatusCodes.Status200OK)]
+    public async Task<IActionResult> Folders(CancellationToken cancellationToken, int skip = 0, int take = 100)
+    {
+        PagedModel<IMediaType> mediaTypes = await _mediaTypeEditingService.GetFolderMediaTypes(skip, take);
+
+        var result = new PagedModel<MediaTypeItemResponseModel>
+        {
+            Items = _mapper.MapEnumerable<IMediaType, MediaTypeItemResponseModel>(mediaTypes.Items),
+            Total = mediaTypes.Total
+        };
+        return Ok(result);
+    }
+}

src/Umbraco.Cms.Api.Management/OpenApi.json

@@ -13217,6 +13217,61 @@
         ]
       }
     },
+    "/umbraco/management/api/v1/item/media-type/folders": {
+      "get": {
+        "tags": [
+          "Media Type"
+        ],
+        "operationId": "GetItemMediaTypeFolders",
+        "parameters": [
+          {
+            "name": "skip",
+            "in": "query",
+            "schema": {
+              "type": "integer",
+              "format": "int32",
+              "default": 0
+            }
+          },
+          {
+            "name": "take",
+            "in": "query",
+            "schema": {
+              "type": "integer",
+              "format": "int32",
+              "default": 100
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Success",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "oneOf": [
+                    {
+                      "$ref": "#/components/schemas/PagedModelMediaTypeItemResponseModel"
+                    }
+                  ]
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "The resource is protected and requires an authentication token"
+          },
+          "403": {
+            "description": "The authenticated user do not have access to this resource"
+          }
+        },
+        "security": [
+          {
+            "Backoffice User": [ ]
+          }
+        ]
+      }
+    },
     "/umbraco/management/api/v1/item/media-type/search": {
       "get": {
         "tags": [
@@ -45027,4 +45082,4 @@
       }
     }
   }
-}
+}

src/Umbraco.Core/Services/ContentTypeEditing/IMediaTypeEditingService.cs

@@ -16,4 +16,6 @@ public interface IMediaTypeEditingService
         IEnumerable<string> currentPropertyAliases);
 
     Task<PagedModel<IMediaType>> GetMediaTypesForFileExtensionAsync(string fileExtension, int skip, int take);
+
+    Task<PagedModel<IMediaType>> GetFolderMediaTypes(int skip, int take);
 }

src/Umbraco.Core/Services/ContentTypeEditing/MediaTypeEditingService.cs

@@ -102,6 +102,35 @@ internal sealed class MediaTypeEditingService : ContentTypeEditingServiceBase<IM
 
     }
 
+    public Task<PagedModel<IMediaType>> GetFolderMediaTypes(int skip, int take)
+    {
+        // we'll consider it a "folder" media type if it:
+        // - does not contain an umbracoFile property
+        // - has any allowed types below itself
+        var folderMediaTypes = _mediaTypeService
+            .GetAll()
+            .Where(mt =>
+                mt.CompositionPropertyTypes.Any(pt => pt.Alias == Constants.Conventions.Media.File) is false
+                && mt.AllowedContentTypes?.Any() is true)
+            .ToList();
+
+        // as a special case, the "Folder" system media type must always be included
+        if (folderMediaTypes.Any(mediaType => mediaType.Alias == Constants.Conventions.MediaTypes.Folder) is false)
+        {
+            IMediaType? defaultFolderMediaType = _mediaTypeService.Get(Constants.Conventions.MediaTypes.Folder);
+            if (defaultFolderMediaType is not null)
+            {
+                folderMediaTypes.Add(defaultFolderMediaType);
+            }
+        }
+
+        return Task.FromResult(new PagedModel<IMediaType>
+        {
+            Items = folderMediaTypes.Skip(skip).Take(take),
+            Total = folderMediaTypes.Count
+        });
+    }
+
     protected override IMediaType CreateContentType(IShortStringHelper shortStringHelper, int parentId)
         => new MediaType(shortStringHelper, parentId);