doc/book/en/devweb/js.rst
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+.. -*- coding: utf-8 -*-
+
+Javascript
+----------
+
+*CubicWeb* uses quite a bit of javascript in its user interface and
+ships with jquery (1.3.x) and parts of the jquery UI library, plus a
+number of homegrown files and also other third party libraries.
+
+All javascript files are stored in cubicweb/web/data/. There are
+around thirty js files there. In a cube it goes to data/.
+
+Obviously one does not want javascript pieces to be loaded all at
+once, hence the framework provides a number of mechanisms and
+conventions to deal with javascript resources.
+
+Conventions
+~~~~~~~~~~~
+
+It is good practice to name cube specific js files after the name of
+the cube, like this : 'cube.mycube.js', so as to avoid name clashes.
+
+XXX external_resources variable (which needs love)
+
+CubicWeb javascript API
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Javascript resources are typically loaded on demand, from views. The
+request object (available as self._cw from most application objects,
+for instance views and entities objects) has a few methods to do that:
+
+* `add_js(self, jsfiles, localfile=True)` which takes a sequence of
+  javascript files and writes proper entries into the HTML header
+  section. The localfile parameter allows to declare resources which
+  are not from web/data (for instance, residing on a content delivery
+  network).
+
+* `add_onload(self, jscode)` which adds one raw javascript code
+  snippet inline in the html headers. This is quite useful for setting
+  up early jQuery(document).ready(...) initialisations.
+
+CubicWeb javascript events
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+* ``server-response``: this event is triggered on HTTP responses (both
+  standard and ajax). The two following extra parameters are passed
+  to callbacks :
+
+  - ``ajax``: a boolean that says if the reponse was issued by an
+    ajax request
+
+  - ``node``: the DOM node returned by the server in case of an
+    ajax request, otherwise the document itself for standard HTTP
+    requests.
+
+Important AJAX APIS
+~~~~~~~~~~~~~~~~~~~
+
+* `asyncRemoteExec` and `remoteExec` are the base building blocks for
+  doing arbitrary async (resp. sync) communications with the server
+
+* `reloadComponent` is a convenience function to replace a DOM node
+  with server supplied content coming from a specific registry (this
+  is quite handy to refresh the content of some boxes for instances)
+
+* `jQuery.fn.loadxhtml` is an important extension to jQuery which
+  allows proper loading and in-place DOM update of xhtml views. It is
+  suitably augmented to trigger necessary events, and process CubicWeb
+  specific elements such as the facet system, fckeditor, etc.
+
+
+A simple example with asyncRemoteExec
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In the python side, we have to extend the BaseController class. The
+@jsonize decorator ensures that the `return value` of the method is
+encoded as JSON data. By construction, the JSonController inputs
+everything in JSON format.
+
+.. sourcecode: python
+
+    from cubicweb.web.views.basecontrollers import JSonController, jsonize
+
+    @monkeypatch(JSonController)
+    @jsonize
+    def js_say_hello(self, name):
+        return u'hello %s' % name
+
+In the javascript side, we do the asynchronous call. Notice how it
+creates a `deferred` object. Proper treatment of the return value or
+error handling has to be done through the addCallback and addErrback
+methods.
+
+.. sourcecode: javascript
+
+    function asyncHello(name) {
+        var deferred = asyncRemoteExec('say_hello', name);
+        deferred.addCallback(function (response) {
+            alert(response);
+        });
+        deferred.addErrback(function (error) {
+            alert('something fishy happened');
+        });
+     }
+
+     function syncHello(name) {
+         alert( remoteExec('say_hello', name) );
+     }
+
+Anatomy of a reloadComponent call
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+`reloadComponent` allows to dynamically replace some DOM node with new
+elements. It has the following signature:
+
+* `compid` (mandatory) is the name of the component to be reloaded
+
+* `rql` (optional) will be used to generate a result set given as
+  argument to the selected component
+
+* `registry` (optional) defaults to 'components' but can be any other
+  valid registry name
+
+* `nodeid` (optional) defaults to compid + 'Component' but can be any
+  explicitly specified DOM node id
+
+* `extraargs` (optional) should be a dictionary of values that will be
+  given to the cell_call method of the component
+
+A simple reloadComponent example
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The server side implementation of `reloadComponent` is the
+js_component method of the JSonController.
+
+The following function implements a two-steps method to delete a
+standard bookmark and refresh the UI, while keeping the UI responsive.
+
+.. sourcecode:: javascript
+
+    function removeBookmark(beid) {
+        d = asyncRemoteExec('delete_bookmark', beid);
+        d.addCallback(function(boxcontent) {
+	    reloadComponent('bookmarks_box', '', 'boxes', 'bookmarks_box');
+            document.location.hash = '#header';
+            updateMessage(_("bookmark has been removed"));
+         });
+    }
+
+`reloadComponent` is called with the id of the bookmark box as
+argument, no rql expression (because the bookmarks display is actually
+independant of any dataset context), a reference to the 'boxes'
+registry (which hosts all left, right and contextual boxes) and
+finally an explicit 'bookmarks_box' nodeid argument that stipulates
+the target DOM node.
+
+Anatomy of a loadxhtml call
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+`jQuery.fn.loadxhtml` is an important extension to jQuery which allows
+proper loading and in-place DOM update of xhtml views. The existing
+`jQuery.load`_ function does not handle xhtml, hence the addition. The
+API of loadxhtml is roughly similar to that of `jQuery.load`_.
+
+.. _`jQuery.load`: http://api.jquery.com/load/
+
+
+* `url` (mandatory) should be a complete url (typically referencing
+  the JSonController, but this is not strictly mandatory)
+
+* `data` (optional) is a dictionary of values given to the
+  controller specified through an `url` argument; some keys may have a
+  special meaning depending on the choosen controller (such as `fname`
+  for the JSonController); the `callback` key, if present, must refer
+  to a function to be called at the end of loadxhtml (more on this
+  below)
+
+* `reqtype` (optional) specifies the request method to be used (get or
+  post); if the argument is 'post', then the post method is used,
+  otherwise the get method is used
+
+* `mode` (optional) is one of `replace` (the default) which means the
+  loaded node will replace the current node content, `swap` to replace
+  the current node with the loaded node, and `append` which will
+  append the loaded node to the current node content
+
+About the `callback` option:
+
+* it is called with two parameters: the current node, and a list
+  containing the loaded (and post-processed node)
+
+* whenever is returns another function, this function is called in
+  turn with the same parameters as above
+
+This mechanism allows callback chaining.
+
+
+A simple example with loadxhtml
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Here we are concerned with the retrieval of a specific view to be
+injected in the live DOM. The view will be of course selected
+server-side using an entity eid provided by the client side.
+
+.. sourcecode:: python
+
+    from cubicweb import typed_eid
+    from cubicweb.web.views.basecontrollers import JSonController, xhtmlize
+
+    @monkeypatch(JSonController)
+    @xhtmlize
+    def js_frob_status(self, eid, frobname):
+        entity = self._cw.entity_from_eid(typed_eid(eid))
+        return entity.view('frob', name=frobname)
+
+.. sourcecode:: javascript
+
+    function update_some_div(divid, eid, frobname) {
+        var params = {fname:'frob_status', eid: eid, frobname:frobname};
+        jQuery('#'+divid).loadxhtml(JSON_BASE_URL, params, 'post');
+     }
+
+In this example, the url argument is the base json url of a cube
+instance (it should contain something like
+`http://myinstance/json?`). The actual JSonController method name is
+encoded in the `params` dictionary using the `fname` key.
+
+A more real-life example from CubicWeb
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A frequent use case of Web 2 applications is the delayed (or
+on-demand) loading of pieces of the DOM. This is typically achieved
+using some preparation of the initial DOM nodes, jQuery event handling
+and proper use of loadxhtml.
+
+We present here a skeletal version of the mecanism used in CubicWeb
+and available in web/views/tabs.py, in the `LazyViewMixin` class.
+
+.. sourcecode:: python
+
+    def lazyview(self, vid, rql=None):
+        """ a lazy version of wview """
+        w = self.w
+        self._cw.add_js('cubicweb.lazy.js')
+        urlparams = {'vid' : vid, 'fname' : 'view'}
+        if rql is not None:
+            urlparams['rql'] = rql
+        w(u'<div id="lazy-%s" cubicweb:loadurl="%s">' % (
+            vid, xml_escape(self._cw.build_url('json', **urlparams))))
+        w(u'</div>')
+        self._cw.add_onload(u"""
+            jQuery('#lazy-%(vid)s').bind('%(event)s', function() {
+                   load_now('#lazy-%(vid)s');});"""
+            % {'event': 'load_%s' % vid, 'vid': vid})
+
+This creates a `div` with a specific event associated to it.
+
+The full version deals with:
+
+* optional parameters such as an entity eid, an rset
+
+* the ability to further reload the fragment
+
+* the ability to display a spinning wheel while the fragment is still
+  not loaded
+
+* handling of browsers that do not support ajax (search engines,
+  text-based browsers such as lynx, etc.)
+
+The javascript side is quite simple, due to loadxhtml awesomeness.
+
+.. sourcecode:: javascript
+
+    function load_now(eltsel) {
+        var lazydiv = jQuery(eltsel);
+        lazydiv.loadxhtml(lazydiv.attr('cubicweb:loadurl'));
+    }
+
+This is all significantly different of the previous `simple example`
+(albeit this example actually comes from real-life code).
+
+Notice how the `cubicweb:loadurl` is used to convey the url
+information. The base of this url is similar to the global javascript
+JSON_BASE_URL. According to the pattern described earlier,
+the `fname` parameter refers to the standard `js_view` method of the
+JSonController. This method renders an arbitrary view provided a view
+id (or `vid`) is provided, and most likely an rql expression yielding
+a result set against which a proper view instance will be selected.
+
+The `cubicweb:loadurl` is one of the 29 attributes extensions to XHTML
+in a specific cubicweb namespace. It is a means to pass information
+without breaking HTML nor XHTML compliance and without resorting to
+ungodly hacks.
+
+Given all this, it is easy to add a small nevertheless useful feature
+to force the loading of a lazy view (for instance, a very
+computation-intensive web page could be scinded into one fast-loading
+part and a delayed part).
+
+On the server side, a simple call to a javascript function is
+sufficient.
+
+.. sourcecode:: python
+
+    def forceview(self, vid):
+        """trigger an event that will force immediate loading of the view
+        on dom readyness
+        """
+        self._cw.add_onload("trigger_load('%s');" % vid)
+
+The browser-side definition follows.
+
+.. sourcecode:: javascript
+
+    function trigger_load(divid) {
+        jQuery('#lazy-' + divd).trigger('load_' + divid);
+    }
+
+
+
+
+XXX reloadComponent
+XXX userCallback / user_callback
+
+Javascript library: overview
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+* jquery.* : jquery and jquery UI library
+
+* cubicweb.ajax.js : concentrates all ajax related facilities (it
+  extends jQuery with the loahxhtml function, provides a handfull of
+  high-level ajaxy operations like asyncRemoteExec, reloadComponent,
+  replacePageChunk, getDomFromResponse)
+
+* cubicweb.python.js : adds a number of practical extension to stdanrd
+  javascript objects (on Date, Array, String, some list and dictionary
+  operations), and a pythonesque way to build classes. Defines a
+  CubicWeb namespace.
+
+* cubicweb.htmlhelpers.js : a small bag of convenience functions used
+  in various other cubicweb javascript resources (baseuri, progress
+  cursor handling, popup login box, html2dom function, etc.)
+
+* cubicweb.widgets.js : provides a widget namespace and constructors
+  and helpers for various widgets (mainly facets and timeline)
+
+* cubicweb.edition.js : used by edition forms
+
+* cubicweb.preferences.js : used by the preference form
+
+* cubicweb.facets.js : used by the facets mechanism
+
+There is also javascript support for massmailing, gmap (google maps),
+fckcwconfig (fck editor), timeline, calendar, goa (CubicWeb over
+AppEngine), flot (charts drawing), tabs and bookmarks.