DD4T 2.2 MultimediaField empty when using Model Service

Question

At this moment I have a DD4T 2.2 .NET webapplication which uses the DXA Model Service (SDL Web 8.5). All my fields are working, except for the Multimedia fields.

The image property in the ViewModel object is null:

My model looks like this:

But the item is also not available in the Component object:

Model Service calls:

The following calls are done from the webapplication (captured by Fiddler):

The response of the PageModel call can be found here (most of the image properties are null). The response of the EntityModel can be found here (image properties are filled).

Rick found out that the Entity Model response is in DXA R2 format (which is a bug?).

The Page Model JSON on the CM-side (using Preview functionality) looks as follows:

{
   "Id":"128733",
   "Title":"Home",
   "PageTemplate":{
      "Id":"128931",
      "Title":"Standaard",
      "FileExtension":"html",
      "RevisionDate":"2019-03-19T14:05:57.12"
   },
   "StructureGroupId":"16859",
   "UrlPath":"/index",
   "Meta":{
      "twitter:card":"summary",
      "og:title":"Home",
      "og:type":"article",
      "og:locale":"en-US",
      "og:image":"tcm:135-128756",
      "description":"Home"
   },
   "Regions":[
      {
         "Name":"Main",
         "Entities":[
            {
               "Id":"128938-128930"
            }
         ],
         "MvcData":{
            "ViewName":"Main"
         }
      }
   ],
   "MvcData":{

   },
   "XpmMetadata":{
      "PageID":"tcm:135-128733-64",
      "PageModified":"2019-03-20T18:33:20.063",
      "PageTemplateID":"tcm:135-128931-128",
      "PageTemplateModified":"2019-03-19T14:05:57.12"
   }
}

For testing I added the component as Embedded CT on the page, the JSON on CM-side for that page looks like this (multimedia values are filled):

{
  "Id": "148023",
  "Title": "Home",
  "PageTemplate": {
    "Id": "148001",
    "Title": "Standaard",
    "FileExtension": "html",
    "RevisionDate": "2019-03-27T07:10:51.883"
  },
  "StructureGroupId": "21456",
  "UrlPath": "/index",
  "Meta": {
    "twitter:card": "summary",
    "og:title": "Home",
    "og:type": "article",
    "og:locale": "en-US",
    "og:image": "tcm:155-147994",
    "description": "Home"
  },
  "Regions": [
    {
      "Name": "Main",
      "Entities": [
        {
          "Id": "147995",
          "ComponentTemplate": {
            "Id": "147998",
            "Title": "Nieuws",
            "RevisionDate": "2019-03-27T09:30:16.433",
            "OutputFormat": "HTML Fragment",
            "Metadata": {
              "controller": "News",
              "action": "ComponentModel",
              "view": "Index"
            }
          },
          "Folder": {
            "Id": "21494",
            "Title": "Nieuws"
          },
          "Content": {
            "title": "Titel",
            "image": {
              "$type": "EntityModelData",
              "Id": "147994",
              "ComponentTemplate": {
                "Id": "147957",
                "RevisionDate": "0001-01-01T00:00:00"
              },
              "Folder": {
                "Id": "21494",
                "Title": "Nieuws"
              },
              "BinaryContent": {
                "Url": "/Preview/Images/logo_tcm155-147994.png",
                "FileName": "logo.png",
                "FileSize": 28332,
                "MimeType": "image/png"
              },
              "SchemaId": "147781"
            },
            "introduction": "Introduction text",
            "paragraphs": {
              "$type": "ContentModelData",
              "title": "Paragraaf 1",
              "body": {
                "$type": "ContentModelData",
                "body": {
                  "$type": "RichTextData",
                  "Fragments": [
                    "\n                <p>Bodytext</p>\n              "
                  ]
                }
              }
            }
          },
          "MvcData": {
            "ControllerName": "News",
            "ActionName": "ComponentModel",
            "ViewName": "Index"
          },
          "XpmMetadata": {
            "ComponentID": "tcm:155-147995",
            "ComponentModified": "2019-03-27T06:54:07.757",
            "ComponentTemplateID": "tcm:155-147998-32",
            "ComponentTemplateModified": "2019-03-27T09:30:16.433",
            "IsRepositoryPublished": false
          },
          "SchemaId": "147976"
        }
      ],
      "MvcData": {
        "ViewName": "Main"
      }
    }
  ],
  "MvcData": {},
  "XpmMetadata": {
    "PageID": "tcm:155-148023-64",
    "PageModified": "2019-03-27T08:25:19.72",
    "PageTemplateID": "tcm:155-148001-128",
    "PageTemplateModified": "2019-03-27T07:10:51.883"
  }
}

The DXA Model Service returns for modelType=DD4T for this page this result (multimedia value is null).

Answer 1

The issue is now reported on GitHub. I found out that there are multiple issues when working with the DXA Model Service together with DD4T. There is an issue related to keywords and there seems also to be an issue with the DD4T.Providers.DxaModelService package, when retrieving Component Presentations with the methods: ComponentPresentationFactory.GetComponentPresentation (throws an error) and ComponentPresentationFactory.GetComponentPresentations (most of the fields are null).

Because of all the articles about the possibility to use the Model Service together with DD4T and the fact that it is supported by SDL I thought it would be a good approach. Now it seems to me that I am the first one ever using this approach on a 'real' project and there is still some work to do.

Since we are at the beginning of our project and facing these kind of issues we decided to stop using this approach en go for the approach DD4T together with the Content Service by using the DD4T.Providers.SDLWeb8.5.CIL package instead of using DD4T.Providers.DxaModelService.

The reason I choose for the DD4T + DXA Model Service approach is mostly because of this article. I was charmed by the promised performance gain. I also share the vision that I prefer a Framework (DD4T) over an customizable webapplication (which DXA is at this moment). When DXA Core is there (the framework) I will surely migrate the application.

Answer 2

Assuming that in your scenario, your View Model represents a Component Presentation which is part of a Page, we can focus on the Page Model JSON (which is correctly DD4T JSON).

There is a problem with this Page Model JSON: you can see that the “image” field is a MultiMedia link field and the JSON includes the expanded linked MM Component. However the Multimedia property of the expanded MM Component is null.

This is potentially a defect in the R2->DD4T conversion in the DXA Model Service.

Can you provide the DXA R2 Page Model JSON as generated by the CM System (that is: do a CM Preview on the Page)?