How can I find Revit document derivatives URNs in BIM360 Docs using the Forge Data Management API

Question

I have some Revit files stored in a BIM360 project. I am trying to visualize those files inside Forge Viewer. Now Forge Viewer won't work directly with Revit file/documents, but require the 'urn' of a translated file, in 'svf' format.

I could transform my Revit file into the 'svf' file using the Forge Model Derivative API, but that consume some credits, and I shouldn't be able to do this because when uploading a Revit file into BIM360, the translation is happening already there.

I was wondering then, how do I find out the 'urn' of the underlying 'svf' file for my Revit document ? I found few resources helping there, when browsing the content of my BIM360 folder, or checking the versions of my Revit document using Forge Data Management API, I should be able to access a derivative object in the response which represent the derived model that can be used by the Forge viewer. https://forums.autodesk.com/t5/bim-360-api-forum/connecting-forge-viewer-with-bim-360/td-p/6742779

However for me, there are no derivatives object in the API response, see below a sample of the API response (I have obfuscated some data for security purpose):

 {
                         "type":  "versions",
                         "id":  "urn:adsk.wipprod:fs.file:vf.XXXXXXXXXXXXXXXXXXXX?version=1",
                         "attributes":  "@{name=139200.33_Amenities Building_R21.rvt; displayName=139200.33_Amenities Building_R21.rvt; createTime=2021-09-03T04:24:18.0000000Z; createUserId=XXXXXXXXXX; createUserName=Holmes Consulting; lastModifiedTime=2021-09-03T04:28:02.0000000Z; lastModifiedUserId=XXXXXXXXXXXX; lastModifiedUserName=XXXXXXXXXX; versionNumber=1; storageSize=19808256; fileType=rvt; extension=}",
                         "links":  "@{self=; webView=}",
                         "relationships":  "@{item=; links=; refs=; downloadFormats=; derivatives=; thumbnails=; storage=}"
                     },

I am using the API call as used in the link I provided above:https://developer.api.autodesk.com/data/v1/projects/:project_id/folders/:folder_id/contents

Why is it that my response contains so little data ?

Answer 1

First thank Eason for contributing.

Since my derivatives object was empty I tried to directly use the 'urn' of my object version.

When listing all my folder documents using the folder get content API method mentioned in my issue, I get all the documents in the 'data' item array and all their versions in the 'included' version array. We need to use the document version id to build the urn. See my sample below:

 "included":  [
                     {
                         "type":  "versions",
                         "id":  "urn:adsk.wipprod:fs.file:vf.l9pc9re6QOmeEVHvTCTlIQ?version=1",
                         "attributes":  "@{name=139200.33_Amenities Building_R21.rvt; displayName=139200.33_Amenities Building_R21.rvt; createTime=2021-09-03T04:24:18.0000000Z; createUserId=XXXXXX; createUserName=XXXXXXXX; lastModifiedTime=2021-09-03T04:28:02.0000000Z; lastModifiedUserId=XXXXXXXXXXXX; lastModifiedUserName=XXXXXXXXXXXX; versionNumber=1; storageSize=19808256; fileType=rvt; extension=}",
                         "links":  "@{self=; webView=}",
                         "relationships":  "@{item=; links=; refs=; downloadFormats=; derivatives=; thumbnails=; storage=}"
                     },

Now the id has to be base64 encoded. I am using https://www.freeformatter.com/base64-encoder.html to encode the id urn:adsk.wipprod:fs.file:vf.l9pc9re6QOmeEVHvTCTlIQ?version=1. Beware the result will be dXJuOmFkc2sud2lwcHJvZDpmcy5maWxlOnZmLmw5cGM5cmU2UU9tZUVWSHZUQ1RsSVE/dmVyc2lvbj0 which is not valid in my JS code to load the document in the Forge Viewer, because of the /. It needs to be replaced with a _. So eventually the bit of JS that load my document into the Forge Viewer looks like this:

var documentId = 'urn:dXJuOmFkc2sud2lwcHJvZDpmcy5maWxlOnZmLmw5cGM5cmU2UU9tZUVWSHZUQ1RsSVE_dmVyc2lvbj0x'; //139200.33_Amenities Building_R21.rvt

Autodesk.Viewing.Initializer(options, function() {

    var htmlDiv = document.getElementById('forgeViewer');
    viewer = new Autodesk.Viewing.GuiViewer3D(htmlDiv);
    viewer.start();
    Autodesk.Viewing.Document.load(documentId, onDocumentLoadSuccess, onDocumentLoadFailure);

    function onDocumentLoadSuccess(viewerDocument) {
        // Choose the default viewable - most likely a 3D model, rather than a 2D sheet.
        var defaultModel = viewerDocument.getRoot().getDefaultGeometry();
        viewer.loadDocumentNode(viewerDocument, defaultModel);
    }

    function onDocumentLoadFailure() {
        console.error('Failed fetching Forge manifest');
    }    

});