model_id null prevents widget rendering in nbviewer

I am modifying my widget’s API (our group is building a custom widget that used the cookiecutter template), which works locally but does not work on nbviewer and I think the problem is that model_id is being set to null. I also could not find documentation on model_id in the docs.

Here is an nbviewer link to my notebook with two widgets made using the two different methods: notebook link. Again, only the first widget renders on nbviewer, but both render locally.

Nbviewer console output tells me that embed-webpack.js is not able to validate widgetViewObject (line 96). I ran a debugger and looked at widgetViewObject, which shows

// the first widget renders and has a model_id
widgetViewObject
Object {model_id: "6bc8e3a09d47486e808ca929bf1c910a"}

// the second widget does not render has has null model_id
widgetViewObject
Object {model_id: null}

[SylvainCorlay]

It is nice that it worked out eventually. Sorry for the late reply.

[cornhundred]

The problem was that my class, Network, which the widget was inheriting from

class clustergrammer_widget(widgets.DOMWidget, Network):

was re-initializing itself when I loaded data and this was causing the error with model_id. I turned off this re-initialization and I am no longer getting a model_id of null in the notebook. I have to better understand why the initialization was causing this problem, but for now it is fixed (see notebook with old and new widget APIs working: notebook link).