diff -r 875bdc0fe8ce -r 105011657405 doc/book/en/development/devweb/js.rst --- a/doc/book/en/development/devweb/js.rst Fri Apr 23 17:07:55 2010 +0200 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,355 +0,0 @@ -.. -*- 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'
' % ( - vid, xml_escape(self._cw.build_url('json', **urlparams)))) - w(u'
') - 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.