Render Rabl templates from view (in order to bootstrap a backbone.js model)

[scottmessinger]

In the backbone.js FAQ, Jeremy suggests bootstrapping a backbone.js model by using ERB and converting the object/collection to json:

<script>
  Accounts.refresh(<%= @accounts.to_json %>);
  Projects.refresh(<%= @projects.to_json(:collaborators => true) %>);
</script>

http://documentcloud.github.com/backbone/#FAQ-bootstrap

How could I render a rabl template in the view instead of calling to_json on the object/collection?

[spoptchev]

Just render the rabl template:

<%= render(:file => 'path_to_rabl_template.json.rabl') %>

[scottmessinger]

Awesome! That's super helpful!

On Fri, Jul 1, 2011 at 9:04 AM, spoptchev <
reply@reply.github.com>wrote:

Just render the rabl template:

<%= render(:file => 'path_to_rabl_template.json.rabl') %>

Reply to this email directly or view it on GitHub:
#42 (comment)

[nesquena]

@scottmessinger Can you confirm this works and if you have run into any other issues? I believe this is how I am doing it in my backbone project as well. Perhaps there should be a guide on the RABL wiki combining backbone and RABL.

[brentmurphy]

Is it also possible to set instance variables for the partial to access using this technique (e.g. for object/collection). Cheers.

[mschulkind]

It seems like you probably need a way to set the object, perhaps with the :object option to render. I'm trying to do this as well, but instead I'm trying to embed the JSON version of object A inside the HTML version of object B. There doesn't appear to be a clean way to do this right now. I think the partial() function in RABL is almost exactly what is needed here.

[nesquena]

Yeah, still trying to figure out the best way to expose this functionality in RABL...

[mschulkind]

To answer my own question somewhat, this works:

1. Create a partial for the object, this has to be named "app/views/model/_foo.json.rabl", note the leading underscore to indicate a partial.
2. In your HTML view: render('model/foo.json.rabl', object: foo_object)

This is not as clean as it could be, but this is 99% of the way there and it works.

[nesquena]

Interesting, that isn't necessarily a bad approach. Thanks for spelling that out. Added that post and a link back to here to the Backbone Integration wiki page as a placeholder. I'd love to flesh out this guide more in the future.

[mschulkind]

Well, I see two possibly cleanups:

1. RABL partial support should enforce the leading underscore to make this less confusing.
2. It'd be nice if the line could be something more like "render(foo_object, :format => :json) " or even "render(json: foo_object)"

I'm not sure if #2 is possible without Rails changes though.

[nesquena]

1. I like RABL supporting partials without underscores because I want to re-use templates I am using in other places as a regular templates
2. Pretty sure this can't be done without messing around in Rails rendering

I am closing this for now because the solution you proposed is good enough

[scottmessinger]

Thanks for all the help with this!

[raine]

Making the rabl file a partial breaks default functionality.

This seems to be the only way around it:

format.json {
  render('lolcats/_index.json.rabl', :object => @cats)
}

[mschulkind]

I'm confused what you're suggesting here.

Your format.json suggests that you're calling this in a controller. Partials are meant for use from views, not controllers.

[raine]

Exactly, and if I make the rabl file a partial, I can't use the same file for both backbone and controller without this hack.

[mschulkind]

But this is precisely what partials are for. How is this any different from how html views work? It just so happens with JSON/RABL, unlike with HTML, that a partial can look just like a full view for the same object, but that doesn't mean the abstractions should be any different.

If you want to have a JSON/RABL partial that can be embedded in other views, you create a partial.
If you happen to also want a view that is nothing more than exactly what is in that partial, then just render the partial in that view.

[willrjmarshall]

Hey,

When I try to do this, the best I can achieve is having "#<Rabl::Engine:0x007fad09cc7320>" rendered into my view.

Is there a way around this?

[mschulkind]

example?

[nesquena]

When you try what specifically? can you gist it?

[willrjmarshall]

If I try this: https://gist.github.com/1297264

I get this: https://gist.github.com/1297266

Looks like to_s being called on the Rabl instance itself.

[mschulkind]

What does the rabl file look like? What's it named?

[willrjmarshall]

rabl file is plates/_index.json.rabl

It looks like this: https://gist.github.com/1297270

[willrjmarshall]

(I've tried switching object to plates as I plan to do eventually, but it doesn't seem to be getting far enough to choke on that)

[mschulkind]

What are you expecting to happen here?

You're passing in a collection of strings, but then expecting them to have attributes.

[willrjmarshall]

I'm expecting it to barf when it sees stuff it can't render.

I've also tried passing in a valid object that can render (when I access this through a controller method), but I get the same "#Rabl::Engine:0x007fad0d4d0500" issue when I render inline.

As far as I can tell, it's not trying to render the .rabl template at all.

[mschulkind]

It's possible the collection part is breaking here, I have code almost identical to this that works, but for some reason I'm doing map{ render(...) }.join(','). Possibly I ran into the same problem.

[nesquena]

Interesting, are you on Rails 3.1? Looks like a bug but not sure how to fix it. I remember trying this before and having it work alright in Rails 2.3.

[mschulkind]

Works for me on Rails 3.

On Tue, Oct 18, 2011 at 9:42 PM, Nathan Esquenazi <
reply@reply.github.com>wrote:

Interesting, are you on Rails 3.1? Looks like a bug but not sure how to fix
it. I remember trying this before and having it work alright in Rails 2.3.

Reply to this email directly or view it on GitHub:
#42 (comment)

[willrjmarshall]

I am on Rails 3.1, which might be the problem.

@mschulkind: even if I empty the .rabl partial the same thing happens, so I don't think it's getting far enough for that to be an issue.

[nesquena]

I know they changed the way rendering works on 3.1 but I don't know how and I don't actually have any 3.1 projects. Just Padrino, Rails 2.3 and Rails 3. So if anyone can help investigate and fix this in a patch, I'd appreciate it.

[mschulkind]

I agree with nesquena, it looks like the template handler wiring isn't quite right, which definitely points to some sort of Rails change.

[mschulkind]

https://github.com/johnf/haml/commit/5cb9e77dcf685865c5b759e5c285d6dd64a4305c

This looks very relevant.

[mschulkind]

stevegraham/twilio-rb#12

...and another just for reference.

[nesquena]

Ah...yes that is extremely relevant. Thanks for tracking that down, looks like they changed the template handler api completely...

[willrjmarshall]

Is there likely to be a workaround for now?

[willrjmarshall]

I'm looking into a patch for this currently. Need the fix anyway :)

[nesquena]

I think the only way forward is to basically either take the haml approach (and try to make one handler for 3/3.1) or split it up in https://github.com/nesquena/rabl/blob/master/lib/rabl/template.rb even further creating a separate handler for 3.1 following stevegraham/twilio-rb#12 example

[willrjmarshall]

Ok, I've made some progress on this:

It's nothing to do with the HAML bug. The problem is that render() in Engine is getting "html" in self.request_format... when it should be "json". A temporary fix looks like this: https://gist.github.com/1297460

Check out line 17 - if we manually force the format to "json" this works as expected.

In the Rails 2 version, the format is being set using

{ :format => #{template.format.inspect} }

format is a private method on ActionView::Template in Rails 3, so we can't do this anymore.

Thoughts?

[willrjmarshall]

Ok, to be ultra-specific, something has changed between Rails 3.0 and Rails 3.1 to make this start returning "html"

    def request_format
      format = self.request_params.has_key?(:format) ? @_scope.params[:format] : nil
      if request = @_scope.respond_to?(:request) && @_scope.request
        format ||= request.format.to_sym.to_s if request.respond_to?(:format)
      end
      format && self.respond_to?("to_#{format}") ? format : "json"
    end

It's getting "html" from

"request.format.to_sym.to_s" 

but the same thing doesn't occur in the Rails 3.0 test-case. Hmmm.....

[willrjmarshall]

#126

[mattiassvedhem]

I've been trying to do as stated in the Wiki under Backbone integration but I can't get the view to render correctly:

render('restaurants/show', formats: :json, object: Restaurant.first)

I've tried to name the template _show.json.rabl show.json.rabl show.json.rabl show.rabl
but without success, I did get this to work:

render('show.json.rabl', object: restaurant).html_safe

But only in another view in the restaurants folder and I need to explictly do show.json.rabl

I'm using Rails 3.2 and Rabl 0.7.0, is there any recent changes on this? is the recommended way to use Rabl::Renderer in views also?

Edit: Oh and as suggested in #126
I've also tried:

render(file: 'restaurants/show', object: Restaurant.first, formats: :json).html_safe

All I get is

ActionView::MissingTemplate: Missing template restaurants/show with {:locale=>[:sv_SE], :formats=>[:json], :handlers=>[:erb, :builder, :coffee, :haml, :rabl, :eco]}. Searched in:

[mschulkind]

Looks like there's relevant discussion going on at #126.

[mattiassvedhem]

Yes, I've tried the suggested methods there, but can't get it to work, only with this, and only if already in a template of the same folder:

render('show.json.rabl', object: restaurant).html_safe

I also need to name the file _show.json.rabl in order for this to work.

[mschulkind]

This has been my experience as well since well before rails 3.1 even.

On Mon, Jul 30, 2012 at 12:08 PM, yeggeps <
reply@reply.github.com

wrote:

Yes, I've tried the suggested methods there, but can't get it to work,
only with this, and only if already in a template of the same folder:

render('show.json.rabl', object: restaurant).html_safe

I also need to name the file _show.json.rabl in order for this to
work.

---

Reply to this email directly or view it on GitHub:
#42 (comment)

[nesquena]

Yeah, sorry this inline rendering stuff is so troublesome. Seems that what you need to do has changed on several occasions even just between Rails 3 and 3.1. If anyone can help update the wiki with the most relevant info, I'd appreciate it. Or if there's a simple way we can improve the template handler registration so this is less painful in the future.

[nesquena]

As you mentioned there's usually a way to pull it off. You can also Rabl.render as you suggested which would be a simpler way to render inline templates if all else fails.

[mattiassvedhem]

So if using Rabl::Renderer or Rabl.render, is there a way to set the default view_path so I don't have to specify it every time?

[mattiassvedhem]

According to the readme on view_paths

If view_paths is set to a path, this view path will be checked for every rabl template within your application. Add to this
path especially when including Rabl in an engine and using view paths within a another Rails app.

it implies that you don't have to explicitly set config.view_paths = ['app/views'] when using Rabl in a normal Rails app, is this correct? It's empty by default so I guess it needs to always be set?