4 Development with MKWS consists primarily of defining new types of
5 widgets. These can interact with the core functionality is several
8 You create a new widget type by calling the mkws.registerWidgetType
9 function, passing in the widget name and a function. The name is used
10 to recognise HTML elements as being widgets of this type -- for
11 example, if you register a "Foo" widget, elements like <div
12 class="mkwsFoo"> will be widgets of this type.
14 The function promotes a bare widget object (passed as `this') into a
15 widget of the appropriate type. MKWS doesn't use classes or explicit
16 prototypes: it just makes objects that have the necessary
17 behaviours. Widgets have *no* behaviours that they have to provide:
18 you can make a doesn't-do-anything-at-all widget if you like:
20 mkws.registerWidgetType('Sluggard', function() {});
22 More commonly, widgets will subscribe to one or more events, so that
23 they're notified when something interesting happens. For example, the
24 "Log" widget asks to be notified when a "log" event happens, and
25 appends the logged message to its node, as follows:
27 mkws.registerWidgetType('Log', function() {
30 this.team.queue("log").subscribe(function(teamName, timestamp, message) {
31 $(that.node).append(teamName + ": " + timestamp + message + "<br/>");
35 This simple widget illustrates several important points:
37 * The base widget object (`this') has several baked-in properties and
38 methods that are available to individual widgets. These include
39 this.team (the team that this widget is a part of) and this.node
40 (the DOM element of the widget).
42 * The team object (`this.team') also has baked-in properties and
43 methods. These include the queue function, which takes an event-name
44 as its argument. It's possible to subscribe to an event's queue
45 using this.team.queue("EVENT").subscribe. The argument is a function
46 which is called whenever the event is published. The arguments to
47 the function are different for different events.
49 * The value of `this' is lost inside the subscribe callback, so it
50 must be saved if it's to be used inside that callback (typically as
51 a local variable named `that').
54 SPECIALISATION (INHERITANCE)
55 ============================
57 Many widgets are simple specialisations of existing widgets. For
58 example, the "Record" widget is the same as the "Records" widget
59 except that it defaults to displaying a single record. It's defined as
62 mkws.registerWidgetType('Record', function() {
63 mkws.promotionFunction('Records').call(this);
64 if (!this.config.maxrecs) this.config.maxrecs = 1;
67 Remember that when a promotion function is called, it's passed a base
68 widget object that's not specialised for any particular task. To make
69 a specialised widget, first promote that base widget into the type
70 that you want to specialise from -- in this case, "Records" -- using
71 the promotion function that's been registered for that type.
73 Once this has been done, the specialisations can be introduced. In
74 this case, it's a very matter of changing the "maxrecs" configuration
75 setting to 1 unless it's already been given an explicit value. (That
76 would occur if the HTML used an element like <div class="mkwsRecord"
77 maxrecs="2">, though it's not obvious why anyone would do that.)
80 WIDGET PROPERTIES AND METHODS
81 =============================
83 String this.type -- a string containing the type of the widget.
85 Team this.team -- the team object to which this widget belongs. The
86 team has several additional important properties and methods,
89 DOMElement this.node -- the DOM element of the widget
91 Hash this.config -- a table of configuration values for the
92 widget. This table inherits missing values from the team's
93 configuration, which in turn inherits from the top-level MKWS
94 configuration, which inherits from the default
95 configuration. Instances of widgets in HTML can set
96 configuration items as HTML attributes, as in <div
97 class="mkwsRecords" maxrecs="2">.
99 String this.toString() -- a function returning a string that briefly
100 names this widget. Can be useful in logging.
102 Void this.log(string) -- a function to log a string for debugging
103 purposes. The string is written on the browser console, and
104 also published to any "log" subcribers.
110 Since the team object is supposed to be opaque to widgets, all access
111 is via the following API methods rather than direct access to
115 Bool team.submitted()
117 Num team.totalRecordCount()
118 Num team.currentPage();
119 String team.currentRecordId() -- simple accessor functions that
120 provide the ability to read properties of the team.
122 Array team.filters() -- another accessor function, providing access to
123 the array of prevailing filters (which narrow the search
124 results by means of Pazpar2 filters and limits). This is
125 really too complicated an object for the widgets to be given
126 access to, but it's convenient to do it this way. See the
127 "Navi" widget, which is the only place it's used.
129 Hash team.config() -- access to the team's configuration
130 settings. There is almost certainly no reason to use this: the
131 settings that haven't been overridden are accessible via
134 Void team.set_sortOrder(string)
135 Void team.set_perpage(number) -- "setter" functions for the team's
136 sortOrder and perpage functions. Unlikely to be needed outside
137 of the "Sort" and "Perpage" widgets.
139 Queue team.queue(eventName)
140 Returns the queue associated with the named event: this can be
141 used to subscribe to the event (or more rarely to publish it).
143 Bool team.targetFiltered(targetId)
147 team.newSearch(query, sortOrder, maxrecs, perpage, limit, targets, targetfilter)
148 team.recordElementId(recordId)
149 team.currentRecordData()
150 team.renderDetails(recordData)
151 team.loadTemplate(templateName)