# ERB in snippets or pages? **URL:** \ **Category:** Radiant CMS\ **Created:** [July 14, 2006, 7:09pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435 "2006-07-14T19:09:16Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 14, 2006, 7:09pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/1 "2006-07-14T19:09:16Z")
The short version: Is it possible to use ERB within Radiant snippets or pages? (By filters maybe?) The long version: I’ve a whole bunch of Rails applications within a same domain including forum, wiki and so-on. They use a common template, implemented by putting together a bunch of common partials, symlinking to their physical location, then including those partials within the default layout for each application. Repetition is minimised with in general only application-specific variations in layouts. Ultimately they’ll also share a secondary, common database with a superset of authorisation/account details for single sign-on purposes. Radiant is used for various reasons, for sections of the site that aren’t publically editable. I’ve expressed the template partials through snippets in Radiant with a default layout. It works well. I’ve extended the snippet “new.rhtml” to include a “more/less”-style panel that takes a filename; the database and table have an “auto\_export” field validated in the model; finally, a custom save method in the snippet controller exports the snippet to the given filename if provided whenever that snippet is updated. This lets me export snippets as partials to the shared directory thus providing control over the look and feel across multiple Rails applications all from within Radiant. Only one problem; no ERB. The snippets use it. In certain cases I’ve been able to hack an equivalent using cunning but hideous arrangements of comments; application-specific partials or snippets are included by commented-out ERB or Radiant tags, then depending on whether Radiant or another app is running, one of those two tags gets expanded so the snippet or partial gets included. The included item closes off the open comment, does its thing, then re-opens the comment again. I said it was hideous… Commented out bits of ERB or Radiant tag end up in the served documents too, which is nasty and it’s an extraordinarily limited approach compared to simply using ERB directly. Any recommendations - is this a job for a filter? ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 14, 2006, 8:01pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/2 "2006-07-14T20:01:58Z")
Andrew H. wrote: > The short version: Is it possible to use ERB within Radiant snippets or > pages? (By filters maybe?) > > … > > Any recommendations - is this a job for a filter? A filter may not be the best choice here. Filters don’t have any concept of where they are being used (the page or snippet). Instead they just filter text. You could make an ERB filter work, but it wouldn’t know anything about where it was being rendered. You may need to resort to doing something with a behavior. Behaviors can control every aspect of how a page is rendered (look at #process on Behavior::Base). You should be able to add a hook in there for evaluating ERB within the context of a page. – John L. [http://wiseheartdesign.com](http://wiseheartdesign.com) ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 16, 2006, 11:54pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/3 "2006-07-16T23:54:33Z")
John W. Long wrote: > A filter may not be the best choice here. Filters don’t have any concept > of where they are being used (the page or snippet). [Use behaviors] Well, I’ve written a simple Filter very quickly that doesn’t have any ERB context around it. ActionView uses much magic to get instance variables into the ERB execution context so that you can use @session et al in your .rhtml files. My Filter doesn’t have that, so it’s quite limited although you can use self-contained ERB quite happily. The ERB parser only works on the bit of text (Snippet, Part) that specifies such a Filter should be run, by definition of how Filters are implemented. I then worked on a Behavior, which has reached its first version that really does inject the local variables in using a similar mechanism to ActionView. This means I can do a footer snippet, say, which includes this (ignoring the line wrapping); angle brackets removed and ‘href’ changed to ‘refh’ to try and get the RForum list gateway to stop saying my message contains spam! Doh! a refh=“[W3C CSS Validator results for http: (CSS level 3 + SVG)](http://jigsaw.w3.org/css-validator/validator?uri=)\<%= url\_encode(@request.protocol + @request.host + @request.request\_uri) %\>” …link text… That’ll produce a valid CSS validation (sic.) URL for any application including Radiant. If included in a Part with the ERB Behavior, it gets parsed. The Snippet or Part that includes such text must, of course, not have any Filters defined which would destructively alter the ERB, so no (say) Textile if you wanted ERB via the Behavior. Then again you can’t have two Filters anyway; at least with an ERB Behaviour you could additionally use a Filter which did not escape or otherwise mangle the ERB code. Now for the catch. Provided all pages using the snippet (via a layout or directly) use the ERB behaviour, all is well. However, what about a Not Found page or an archive? That would probably use the same layout as other pages in a site, which wants directly or via a Snippet to include ERB. But it already has the Not Found Behavior, so it can’t have ERB Behavior too. So, suddenly, I’m back at wanting an ERB filter; the fact that you use ERB somewhere really is something specific to that block of text, whereas a behavior seems to imply application of a concept globally, to the whole compiled page. I’ll look into what instance variables are available for Filter objects tomorrow maybe, but for now you can look at the in-progress code here: [Pond's Place: Ruby software](http://pond.org.uk/ruby/) ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 17, 2006, 6:02pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/4 "2006-07-17T18:02:32Z")
Andrew H. wrote: > the whole compiled page. > You should consider overriding Behavior::Base#render\_page in a plugin. > This would be the easiest way to give all pages and snippets global > access to ERB. – John ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 19, 2006, 3:05pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/5 "2006-07-19T15:05:15Z")
Oliver B. wrote: > What I have done in the past is to create a page with the particular > behavior and then create a snippet that includes the page, this snippet > can then be included into every other page, while original page with > the ERB behavior is executed in the ERB behavior context and the current > page you are looking at in its own behavior context. This sounds potentially cunning but I don’t quite follow; how do you include a particular page from a snippet? Is it possible to manage layouts in this context, given the layout includes the ERB and parsed layouts are included within the scope of Behaviors? > Of course, instead > of going the way through a snippet you can use \ directly. My installation of Radiant 0.50 doen’t recognise \ in pages or snippets. ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 19, 2006, 6:10am UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/6 "2006-07-19T06:10:55Z")
On 16-Jul-2006 23:54 +0200, Andrew H. was heard to say: > John W. Long wrote: > > > A filter may not be the best choice here. Filters don’t have any concept > > of where they are being used (the page or snippet). [Use behaviors] > > Provided all pages using the snippet (via a layout or directly) use the > ERB behaviour, all is well. However, what about a Not Found page or an > archive? That would probably use the same layout as other pages in a > site, which wants directly or via a Snippet to include ERB. But it > already has the Not Found Behavior, so it can’t have ERB Behavior too. What I have done in the past is to create a page with the particular behavior and then create a snippet that includes the page, this snippet can then be included into every other page, while original page with the ERB behavior is executed in the ERB behavior context and the current page you are looking at in its own behavior context. Of course, instead of going the way through a snippet you can use \ directly. Oliver ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 19, 2006, 3:43pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/7 "2006-07-19T15:43:46Z")
On 19-Jul-2006 15:05 +0200, Andrew H. was heard to say: > layouts in this context, given the layout includes the ERB and parsed > layouts are included within the scope of Behaviors? Yes, that should be possible. You should be able to include the content of a specific page into a layout, while this included page is rendered within its own behavior context. > > Of course, instead > > of going the way through a snippet you can use \ directly. > > My installation of Radiant 0.50 doen’t recognise \ in > pages or snippets. Ooops, I ment \\\ so for example: \ \ \ That is how I am including live search in my sidebar. Cheers, Oliver ---
**Author:** ![pond](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/7ab992/32.png) [@pond](https://www.ruby-forum.com/u/pond)\ **Post date:** [July 19, 2006, 7:47pm UTC](https://www.ruby-forum.com/t/erb-in-snippets-or-pages/98435/8 "2006-07-19T19:47:12Z")
You wrote: > What I have done in the past is to create a page with the particular > behavior and then create a snippet that includes the page, this snippet > can then be included into every other page, while original page with the > ERB behavior is executed in the ERB behavior context and the current page > you are looking at in its own behavior context. Thanks for your help with this. Unfortunately I tried it using ‘find’ to build what you suggest and it didn’t work. This is almost certainly because a “Not found” behavior page gets automatically selected whenever something else cannot be found. That page gets parsed, inserts a snippet, the snippet inserts the actual “Not found” page - however, it is the _first_ page in that set which gets incorporated into a layout, which means the ERB in the snippets that the layout includes does not get executed since the first page does not have ERB behavior. It it is impossible to get a page with the ERB behavior included _first_ because a “Not found” page is automatically chosen. For other behavior types your suggestion should work though it will always be the case that the first page in a set of pages is the one that dominates the behavioral context since its layout will be the one that is used for the final rendered result. Including page parts thereafter, by any mechanism, does not include anything that goes around those parts. I still believe that the only way to achieve the specific result I wanted originally would be to use a text filter but it would need knowledge of the wider application environmet - @controller, @session, @request and so-on - indeed, this thread is perilously similar in fundamental concept to another one where somebody is trying to get ActionController::Base included in a behavior so that Rails helper methods are available to that behavior code. The argument seems to be that behaviors and filters need access to application environmental variables - if it’s good enough for .rhtml files in Rails applications it ought to be good enough for page components in Radiant. Given that Radiant is meant to be a lightweight CMS, of course, this might be considered unnecessary application bloat. That would defeat what I’m trying to do, but would be an entirely understandable position. It should at least not be too big a job to modify my own Radiant installation to pass similar variables to a Filter-derived class as are already available to Behavior-derived classes; this wouldn’t let me do Rails helper methods but would provide enough for the limited ERB I have in mind.