Previewing Page Templates

Intro

It is always nice to see the effects of changes immediately and without much effort. Page Templates within Plone usually need a special context to render nicely, for example a content object.

This how to helps you to set up your favorite HTML Editor to show page templates within context as preview. I use HTML Kit for explanation but I bet you can do that with your Editor as well as long as its preview can be set up to use a web server.

The principle here is to set up a script which will automatically select an appropriate context for your template when a preview URL is launched from within a HTML editor.

Steps

1. Add the following script to portal_skins/custom and name it 'preview_template':

     ## Script (Python) "preview_template"
     ##bind container=container
     ##bind context=context
     ##bind namespace=
     ##bind script=script
     ##bind subpath=traverse_subpath
     ##parameters=catalog_sequence
     ##title=
     ##
   
     request = container.REQUEST
     RESPONSE =  request.RESPONSE
   
     # dict 'preview' contains the template names as keys
     # and the URL to the preview context as values.
   
     preview = {'member_search_form.pt' : '/Plone/Members/index_html',
                'index_html.pt' : '/Plone'}
   
     passed_template = request.traverse_subpath[-1]
   
     RESPONSE.redirect(preview[passed_template])
   

2. Configure the preview to use a web server and point it to the above script.

   In HTML Kit you find the settings under Edit->Preferences. Open the Preview-Tab, hit the Edit preview roles Button and enter a preview rule under Path to server mappings. Here you map the path to templates with a server address for the preview. In other editors, look for an option which will let you set the URL to prepend to the name of your script when launching a preview. You must set this to the preview_template script above, so that this can select an appropriate context and redirect your browser to it.

   The following values would show the standard Plone templates from a Plone site on localhost:

      File Path: c:\Plone\data\Products\CMFPlone\skins
   
      Server Address: http://localhost:8080/Plone/preview_template/
   

3. Add page templates and their corresponding preview contexts to the preview dictionary as shown with member_search_form.pt.
4. You may want to add content objects for testing to your Plone Site. I recommend creating a dedicated folder for that purpose as you can easily ex- and import your test objects to other instances later on.

Open Questions

I do not yet know how to test search result pages. Comments are welcome.

Ideas

This is just a quick and dirty solution. It works well for me but it could quite easily be enhanced. Here are some ideas:

1. Replace the dictionary by properties.
2. Catch calls to page_templates that are not yet registered and display a form to add the context information.
3. Create a tool that stores the preview infos in objects, handles muliple views for one page template, creates a preview-walk-trough, restricts permissions, etc. etc.