integration in discourse

Thanks! Also, thanks for bringing up Onebox. Useful to know about.

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Flipping this around a bit, does Discourse itself act as an oEmbed provider? For example, if I link to a Discourse thread from a Considerit proposal, could I get a nice onebox representation of the activity in the Discourse thread that I can embed on Considerit? I’m looking at the meta data of this thread’s html and I don’t see oEmbed endpoints advertised. It would be great to be able to richly link both ways!

edit: looks like Discourse implements OpenGraph, not oEmbed. Sorry for the spam, still learning about these standards!


You can test any website here:


Every time I post here, I learn something new and useful, from a different person.


Sounds like the Stack Overflow effect :wink:

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Hi again!

I think I have oEmbed working for proposals (JSON oEmbed endpoint example, XML oEmbed endpoint example). Furthermore, these oEmbed endpoints are discoverable in the meta tags of any considerit proposal, as per the oEmbed specs.

Considerit oEmbed endpoints specify a “rich” type, i.e. HTML. This HTML is mostly just an iframe, which of course is nice because it creates a separate execution environment to prevent conflicts with the embedding page. The HTML also loads a small javascript library into the containing window which resizes the iframe whenever the content inside the iframe changes height. The author of this library asserts that the library is engineered to play nicely with the containing window.

For a demonstration, go to, input “”, and view the oEmbed result.

I’d like to test it with Discourse, which I think requires whitelisting considerit proposals. The domain to add is https://*

What is the best way to proceed?

Thanks again,

p.s. @Falco, the testing link to iframely/embed was useful, but it won’t work for domains they haven’t already whitelisted. It led me to though, which worked quite nicely.

p.p.s. I think the first pass at embedding considerit proposal results is already pretty nice…we got histograms!


If you have a sample to use I can whitelist it on my sandbox in a few minutes.

Do you mean an example url? If so, here’s one: Mist GUI with live graphs of proposals/votes

Testing with should suffice, as long as it passes there we are usually good!


iframely definitely looks good. :slight_smile:


Hi folks, any update about the status of getting considerit whitelisted for oneboxing in Discourse?

I did a test at to see if whiteboxing would work. I received a Onebox badge for posting a considerit link, but I never saw a Onebox (though when I examine the link tag in the DOM, it has a Onebox class). I don’t know though if this happens to all links posted in Discourse regardless of whether they are whitelisted as oneboxable or not!


Simplest way to get traction here would be a PR to GitHub - discourse/onebox: A gem for turning URLs into website previews ultimately this is @codinghorror’s call on adding more to the whitelists out-of-the-box.

This is the current default list of oembed/opengraph based whitelist:



I created a pull request at (cc: @codinghorror)

Please let me know if I should do anything else.



Hi, I tried adding it manually to our whitelist

unfortunately nothing is getting oneboxed - if I paste a link, it just shows the link, but no Iframe is being generated.

Dear people,

I’ve resolved this issue.

While debugging, I discovered a discrepancy between and onebox’s oembed requests that caused the failure. This might be of interest to @codinghorror, as he says “as long as it passes [at iframely] we are usually good”. Most likely, I’m the only one who will ever be tripped up by this discrepancy. But maybe not, so I thought I’d describe it.

iframely makes the request to considerit’s server with HTML Content-Type set. Onebox does not. The considerit controller that handles initial page load of non-json requests has a respond_to :html constraint on the format. So the controller just returned 404 because it refused to process a non-HTML request. Removing the constraint makes it work.

A mostly working Discourse example with considerit embed: I’ll write a followup post for why I say “mostly”.

Thanks for all your help.


Hey, great work! And please write the followup because I’m very interessed on those custom onebox.

About you iframe resize problem, I think the google docs onebox resizes it, so check that code for some clues.

There is one, hopefully final, hurdle to fully working considerit oembed: consistent iframe resizing.

Embedding in a Discourse thread works sometimes. But it often doesn’t run the javascript that invokes the resizing.

I haven’t pinned it down, but here is one curious way I can replicate in Discourse:

  • doesn’t resize if I just load a thread with a considerit link
  • if I have the editor open for the post with the link, the iframe resize works in the thread (but not the preview)

This holds true across refreshes.

So there’s something special that seems to happen in Discourse during edit post mode.

I recorded this riveting 40 second video to demonstrate the behavior.

I’ve had a frustrating past several hours trying to figure it out. If anyone has insights, I would really appreciate it!



From my earlier post, the oembed html snippet that considerit returns includes: “…mostly just an iframe…The HTML also loads a small javascript library into the containing window which resizes the iframe whenever the content inside the iframe changes height. The author of this library asserts that the library is engineered to play nicely with the containing window.”

The specific code is e.g. :

   <iframe id='considerit-embed-4186' src='' width='700' frameborder='0' style='overflow:hidden' scrolling='no'></iframe>
   <script src=''></script>
   <script type='application/javascript'>
     var resize_interval=setInterval(function(){
       if (typeof iFrameResize != 'undefined'){
         iFrameResize({log:false, checkOrigin:false}, document.getElementById('considerit-embed-4186'))
     }, 40)

More specifically, I don’t understand why edit post mode would trigger the iframe resizing. Does Discourse/Onebox do anything to prevent a script loaded via Onebox from running except when it is initially oneboxed?

Knowing if there is some special treatment of oembeded-javascript in Onebox would help me greatly in what I investigate to solve this issue.


Anyone have any promising leads for me? :slight_smile:

Even just a “nope, no idea what might be happening” would be useful, as I’ll then know I’m on my own!

I’ve extracted and updated my latest question into its own thread in hopes of attracting the attention of someone who can help, at Attention Onebox experts: Help requested resizing an iFrame embedded via oEmbed

I have a foreboding though that the dynamic resizing strategy I outlined above is going to turn out to not to work within Discourse :frowning:

Thanks for everyone’s help here.