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#acl IanRiley:read,write,delete,revert,admin All:read

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= Processing Instruction - Default Action =
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== Background and rationale ==

MoinMoin pages, unless otherwise specified in the URL query string, are displayed with the default action `show`, which is of course quite appropriate for most situations. If another action is preferred, it is possible to provide a page link specifying that action, for example `[[PageName||&action=print]]` or `[[http://wiki.net.PageName?action=print]]`.  However, it would be useful to have a processing instruction that overrides the default action, especially for pages intended for users that only have read rights.

The motivation here was to allow pages to be displayed by default as a PDF using the user-defined action, [[PDF.py]]. This would be useful where you want users to save a format-stable copy of the the page for future reference from the web, rather than having to supply it as an attached file, either to a MoinMoin page or an email.

== Description ==

A new processing instruction, `#action`, is included to override the default `action=show`.

Setting this new processing instruction does not override any action request explicitly given in the page link or URL. 

== Usage ==

Specify a default action (action-name) for the page if none is otherwise requested.

{{{
#action action-name
}}}

Where, `action-name` is either a system-defined or user-defined action.

== Example ==

The raw content of [[PiAction/Example]] is:

{{{
#action PDF
<<Include(PiAction)>>
}}}

The processing instruction `#action PDF` makes the PDF action (see [[PDF.py]]) the  default and, for the purpose the an example, the Include macro gives the page content from here (i.e. [[PiAction]]).

Click on the page link, [[PiAction/Example]], to see it displayed as a PDF.

== Prerequisites ==

To allow the processing instruction `#action` to be recognised `MoinMoin.page.py` needs to be modified in the following two places. 

In the function `MoinMoin.page.parse_processing_instructions`, add the following code in the position indicated.

'''Additional code 1'''

{{{#!python

            elif verb == "action": #added to override default action=show [IanRiley 10.6.14]
                if args.strip():            
                    pi['action'] = args.strip()

}}}

'''Insertion position 1'''

{{{#!python

    def parse_processing_instructions(self):
...
        for verb, args in meta:
...
            elif verb == "pragma":
...

#Additional code goes here.

}}}

In the function `MoinMoin.page.send_page`, add the following code in the position indicated.

'''Additional code 2'''

{{{#!python

        if 'action' in pi and not ('action' in request.values or content_only):
            # force override  default action=show [IanRiley 10.6.14]
            redirect_url = Page(request, self.page_name).url(request,
                                         querystr={'action': pi['action'], }, )
            request.http_redirect(redirect_url)
            return

}}}

'''Insertion position 2'''

{{{#!python

    def send_page(self, **keywords):
...
        pi = self.pi

#Additional code goes here.

}}}

== History ==

Developed with inspiration and MoinMoin code from:

 . @copyright: 2000-2004 by Juergen Hermann <jh@web.de>
 . @copyright: 2005-2008 by MoinMoin:ThomasWaldmann
 . @copyright: 2006 by MoinMoin:FlorianFesti
 . @copyright: 2007 by MoinMoin:ReimarBauer

== Copyright ==

 . @copyright: 2014 Ian Riley <ian@riley.asia>

== License ==

GNU GPL, see COPYING for details.

== Known issues and limitations ==

 * None identified.

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 Hits:: <<Hits>>