RenderPlugin

Render WikiApplications asynchronously

Description

This plugin implements a couple of REST handlers to feetch content from a Foswiki backend. This can either be returned as plain content (via the template handler) or encoded in a JSON object that logs required css and js in addition to the content block (via the jsonTemplate handler).

These can be used to easily replace a server-side INCLUDE with a functional equivalent using a javascript call to one of these REST handlers.

This comes in handy to asynchronously load content in a tabbed interface, loading subsequent content for a treeview, a menu widget, or tooltips.

You may also use it to just render a snippet of TopicMarkup on the server and return a HTML preview back to the browser.

The REST handlers of this plugin have been designed to be rather generic. So, besides some very basic parameter checking, most error handling is up to the callback analysing the return value of the REST handler. The main purpose is best described as being an intermediate transport device.

Compare this to other plugins that implement more specific REST handlers. As such, they are rather tailored to one specific service and thus will be dealing with error cases on the server side in much more detail.

The advantage of using this plugin's REST handler is that you don't have to implement service backends using perl. Instead, you can write TopicFunctions that contain the WikiApplication to be executed when it is called by an appropriate ajax request. This basically is the client side equivalent of a parametrized INCLUDE, as it is used on server side WikiApplications (see examples below).

Syntax

The available REST handlers are:

Handler	Parameters	Description
template	name, expand, render, filename	this handler loads the template name and expands the macro given in expand; the render flag indicates whether the result is to be rendered in addition to common tags being interpreted
jsonTemplate	name, , expand, render	same as template handler, but returns a json object holding css and js zones required to properly format the template; used via foswiki.loadTemplate()

Deprecated Handler	Parameters	Description
expand	text	expands common variables in the submitted text fragment, filename
render	text	same as expand but also renders TopicMarkup converting it to HTML
tag	name, param, *, render, filename	this is a convenience function to expand one specific variable instead of having to build up a snippet of code that you want to expand or render; The param parameter specifies the default parameters to this tag; the named-params are additional named parameters; the render flag indicates if the result is to be expanded only or if it should be renderd into HTML; default is off, that is only expand common tags but don't interpret TopicMarkup

Usage

TODO: come up with some examples for the non-deprecated handlers

The REST handlers are called like this:

%SCRIPTURLPATH{"rest"}%/RenderPlugin/render?text=%ENCODE{"This is _very_ cool."}%

%SCRIPTURLPATH{"rest"}%/RenderPlugin/tag?name=INCLUDE;param=Applications.RenderWebTagCloud;search=screenshot

(equivalent to a %INCLUDE{"Applications.RenderWebTagCloud" search="screenshot"}%)

This can be schedule using jQuery like this:

<div id="container"></div>

<literal>
<script>
jQuery(function($) {
  $("#container").load("<url-to-rest-handler->");
});
</script>

foswiki.loadTemplate: JavaScript API to load JSON content

The foswiki.loadTemplate() function can be used to load content from the backend using the jsonTemplate handler and inject it into the current DOM including all JavaScript and CSS as required by the collected content (via Foswiki::Func::addToZone() or %JQREQUIRE or %ADDZOZONE). These additional assets will be added to the respective zones of the page if not already present.

Parameter	Description	Defaults
name	name of the template to load (required)
expand	name of the TMPL:DEF to expand (required)
topic	Foswiki address from where to process the response	current web.topic
url	url from where to load content	/wiki/bin/rest/RenderPlugin/jsonTemplate
debug	boolean switch to enable debug output on the conosole	false
render	switch on TML rendering on the backend	on
zones	list of zones to return	script, head
async	boolean flag to add the async attribute to script and style assets	false
cachecontrol	caching behaviour of loaded content: specifies the number of seconds the returned JSON content is to be cached by the browser	0
...	any other parameter is passed to the REST handler as is

Note that =foswiki.loadTemplate() returns a jqXHR promise:

foswiki.loadTemplate({
  "name": "user",
  "expand": "photo"
  "topic": foswiki.getPreference("WIKIUSERNAME")
}).done(function(data) {
  var $content = $(data.expand);
  $(body).append($content);
});

foswikiDialogLink: load jQuery dialogs as JSON content

While JQueryPlugin comes with a dialog loader of its own, it lacks the additional handling of assets required to render the dialog properly, i.e. JavaScript to initialize it. This is mitigated using the CSS class foswikiDialogLink on an anchor element or any other clickable button.

Example:

Add

%JQREQUIRE{"FoswikiTemplate"}%

to process all foswikiDialogLink elements of the current page.

such as

<a href="#backlinks" class="foswikiDialogLink">Display backlinks of the current topic</a>

If a user clicks on this link will it load the backlinks template and return the TMPL:DEF{"dialog"} definition as a JSON object inject the dialog into the page and open it.

The backlinks.tmpl content must have a jqUIDialog definition similar to:

%TMPL:DEF{"dialog"}%<div class="jqUIDialog" data-modal="true" data-height="600" data-width="930" data-draggable="true" data-resizable="true" title="Backlinks to <nop>%WEB%.%TOPIC%">
...
<a class="jqUIDialogButton jqUIDialogClose" data-icon="ui-icon-cancel">%MAKETEXT{"Close"}%</a>
</div>%TMPL:END%

Note, the foswikiDialogLink can be customized using HTML5 data parameters such as in:

<a class="foswikiDialogLink" data-name="..." data-expand="..." data-...>Click me</a>

See the list of parameters for the foswiki.loadTemplate() API.

Examples

Fetching a message

%STARTSECTION{"message"}%
*Hello World!* :)
%ENDSECTION{"message"}%

Previewing TML

Okay, your turn to create an example calling SEARCH.

Installation Instructions

You do not need to install anything in the browser to use this extension. The following instructions are for the administrator who installs the extension on the server.

Open configure, and open the "Extensions" section. "Extensions Operation and Maintenance" Tab -> "Install, Update or Remove extensions" Tab. Click the "Search for Extensions" button. Enter part of the extension name or description and press search. Select the desired extension(s) and click install. If an extension is already installed, it will not show up in the search results.

You can also install from the shell by running the extension installer as the web server user: (Be sure to run as the webserver user, not as root!)

cd /path/to/foswiki
perl tools/extension_installer <NameOfExtension> install

If you have any problems, or if the extension isn't available in configure, then you can still install manually from the command-line. See https://foswiki.org/Support/ManuallyInstallingExtensions for more help.

Dependencies

None

Change History

29 Apr 2022:	deprecated expand and render REST handler, added whitelist of allowed macros to tag REST handler
14 Oct 2020:	improved cacheability of rest handlers; new class foswikiDialogLink to ease creating dialogs
14 Feb 2019:	make template loader available to javascript as a proper jQuery module
16 Jan 2017:	added filename to rest handler to override it in the content-dispisition header
29 Apr 2016:	added support for newer Foswiki engines
31 Aug 2015:	implemeted JSON-Template REST handler
04 Apr 2014:	flag rest handlers that don't require authentication
18 Mar 2014:	removed duplicate http header from render rest handler
01 Nov 2013:	added support for contenttype url parameter
10 Jan 2012:	some docu fixes
12 May 2009:	added template handler
24 Apr 2009:	converted to foswiki plugin
07 Jan 2009:	added upload rest handler; fixes for foswiki and FastCGIContrib
11 Jul 2008:	initial version