--- /dev/null
+INTRODUCTION
+============
+
+Development with MKWS consists primarily of defining new types of
+widgets. These can interact with the core functionality is several
+defined ways.
+
+You create a new widget type by calling the mkws.registerWidgetType
+function, passing in the widget name and a function. The name is used
+to recognise HTML elements as being widgets of this type -- for
+example, if you register a "Foo" widget, elements like <div
+class="mkwsFoo"> will be widgets of this type.
+
+The function promotes a bare widget object (passed as `this') into a
+widget of the appropriate type. MKWS doesn't use classes or explicit
+prototypes: it just makes objects that have the necessary
+behaviours. Widgets have *no* behaviours that they have to provide:
+you can make a doesn't-do-anything-at-all widget if you like:
+
+ mkws.registerWidgetType('Sluggard', function() {});
+
+More commonly, widgets will subscribe to one or more events, so that
+they're notified when something interesting happens. For example, the
+"Log" widget asks to be notified when a "log" event happens, and
+appends the logged message to its node, as follows:
+
+ mkws.registerWidgetType('Log', function() {
+ var that = this;
+
+ this.team.queue("log").subscribe(function(teamName, timestamp, message) {
+ $(that.node).append(teamName + ": " + timestamp + message + "<br/>");
+ });
+ });
+
+This simple widget illustrates several important points:
+
+* The base widget object (`this') has several baked-in properties and
+ methods that are available to individual widgets. These include
+ this.team (the team that this widget is a part of) and this.node
+ (the DOM element of the widget).
+
+* The team object (`this.team') also has baked-in properties and
+ methods. These include the queue function, which takes an event-name
+ as its argument. It's possible to subscribe to an event's queue
+ using this.team.queue("EVENT").subscribe. The argument is a function
+ which is called whenever the event is published. The arguments to
+ the function are different for different events.
+
+* The value of `this' is lost inside the subscribe callback, so it
+ must be saved if it's to be used inside that callback (typically as
+ a local variable named `that').
+
+
+SPECIALISATION (INHERITANCE)
+============================
+
+Many widgets are simple specialisations of existing widgets. For
+example, the "Record" widget is the same as the "Records" widget
+except that it defaults to displaying a single record. It's defined as
+follows:
+
+ mkws.registerWidgetType('Record', function() {
+ mkws.promotionFunction('Records').call(this);
+ if (!this.config.maxrecs) this.config.maxrecs = 1;
+ });
+
+Remember that when a promotion function is called, it's passed a base
+widget object that's not specialised for any particular task. To make
+a specialised widget, first promote that base widget into the type
+that you want to specialise from -- in this case, "Records" -- using
+the promotion function that's been registered for that type.
+
+Once this has been done, the specialisations can be introduced. In
+this case, it's a very matter of changing the "maxrecs" configuration
+setting to 1 unless it's already been given an explicit value. (That
+would occur if the HTML used an element like <div class="mkwsRecord"
+maxrecs="2">, though it's not obvious why anyone would do that.)
+
+
+WIDGET PROPERTIES AND METHODS
+=============================
+
+String this.type
+ A string containing the type of the widget.
+
+Team this.team
+ The team object to which this widget belongs. The team has
+ several additional important properties and methods, described
+ below.
+
+DOMElement this.node
+ The DOM element of the widget
+
+Hash this.config
+ A table of configuration values for the widget. This table
+ inherits missing values from the team's configuration, which
+ in turn inherits from the top-level MKWS configuration, which
+ inherits from the default configuration. Instances of widgets
+ in HTML can set configuration items as HTML attributes, as in
+ <div class="mkwsRecords" maxrecs="2">.
+
+String this.toString()
+ A function returning a string that briefly names this
+ widget. Can be useful in logging.
+
+Void this.log(string)
+ A function to log a string for debugging purposes. The string
+ is written on the browser console, and also published to any
+ "log" subcribers.
+
+
+TEAM METHODS
+============
+
+Since the team object is supposed to be opaque to widgets, all access
+is via the following API methods rather than direct access to
+properties.
+
+String team.name()
+Bool team.submitted()
+Num team.perpage()
+Num team.totalRecordCount()
+Num team.currentPage();
+String team.currentRecordId()
+String team.currentRecordData()
+ Simple accessor functions that provide the ability to read
+ properties of the team.
+
+Array team.filters()
+ Another accessor function, providing access to the array of
+ prevailing filters (which narrow the search results by means
+ of Pazpar2 filters and limits). This is really too complicated
+ an object for the widgets to be given access to, but it's
+ convenient to do it this way. See the "Navi" widget, which is
+ the only place it's used.
+
+Hash team.config()
+ Access to the team's configuration settings. There is almost
+ certainly no reason to use this: the settings that haven't
+ been overridden are accessible via this.config.
+
+Void team.set_sortOrder(string)
+Void team.set_perpage(number)
+ "Setter" functions for the team's sortOrder and perpage
+ functions. Unlikely to be needed outside of the "Sort" and
+ "Perpage" widgets.
+
+Queue team.queue(eventName)
+ Returns the queue associated with the named event: this can be
+ used to subscribe to the event (or more rarely to publish it).
+
+Bool team.targetFiltered(targetId)
+ Indicates whether the specified target has been filtered by
+ selection as a facet.
+
+Void team.newSearch(query, sortOrder, maxrecs, perpage, limit, targets, targetfilter)
+ Starts a new search with the specified parameters. All but the
+ query may be omitted, in which case the prevailing defaults
+ are used.
+
+Void team.reShow()
+ Using the existing search, re-shows the result records after a
+ change in sort-order, per-page count, etc.
+
+String team.recordElementId(recordId)
+ Utility function for converting a record identifer (returned
+ from Pazpar2) into a version suitable for use as an HTML
+ element ID.
+
+String team.renderDetails(recordData)
+ Utility function returns an HTML rendering of the record
+ represented by the specified data.
+
+Template team.loadTemplate(templateName)
+ Loads (or retrieves from cache) the named Handlebars template,
+ and returns it in a form that can be invoked as a function,
+ passed a data-set.
+
+Some of these methods either (A) are really too low-level and should
+not be exposed, or (B) should be widget-level methods. The present
+infelicities reflect the fact that some code that rightly belongs in
+widgets is still in the team. When we finish migrating it, the widget
+API should get simpler.
+
projects / mkws-moved-to-github.git / commitdiff