% 11 August 2014
-INTRODUCTION
-============
+Overview
+========
+
+Core concepts
+-------------
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
+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.
+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
+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:
+behaviours. There are _no_ behaviours that Widgets are obliged 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
+`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;
+ var that = this;
- this.team.queue("log").subscribe(function(teamName, timestamp, message) {
- $(that.node).append(teamName + ": " + timestamp + message + "<br/>");
- });
+ 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
+* 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).
+ `this.team` (the team that this widget is a part of) and `this.node`
+ (the DOM element of the widget). See below for a full list.
+
+* 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. See below for a full list.
-* 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.
+* You can add functionality to a widget by subscribing it 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').
+* As with so much JavaScript programming, the value of the special
+ variable `this` is lost inside the `subscribez` callback function,
+ so it must be saved if it's to be used inside that callback
+ (typically as a local variable named `that`).
-SPECIALISATION (INHERITANCE)
-============================
+Widget specialisation (inheritance)
+-----------------------------------
Many widgets are simple specialisations of existing widgets. For
-example, the "Record" widget is the same as the "Records" widget
+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;
+ 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
+a specialised widget, you 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 simple matter of changing the "maxrecs"
+this case, it's a very simple 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
+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
-=============================
+Reference Guide
+===============
+
+
+Widget properties and methods
+-----------------------------
+
+The following properties and methods exist in the bare widget object
+that is passed into `registerWidgetType`'s callback function, and can
+be used by the derived widget.
-String this.type
+* `String this.type` --
A string containing the type of the widget.
-Team this.team
+* `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
+* `DOMElement this.node` --
The DOM element of the widget
-Hash this.config
+* `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">.
+ in HTML can set configuration items as HTML attributes: for
+ example, the HTML element
+ `<div class="mkwsRecords" maxrecs="10">`.
+ creates a widget for which `this.config.maxrecs` is set to 10.
-String this.toString()
+* `String this.toString()` --
A function returning a string that briefly names this
widget. Can be useful in logging.
-Void this.log(string)
+* `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.
+ subcribers to the `log` event.
-String this.value()
+* `String this.value()` --
A function returning the value of the widget's HTML element.
-
-TEAM METHODS
-============
+* `VOID autosearch()` --
+ Registers that this kind of widget is one that requires an
+ automatic search to be run for it if an `autosearch` attribute
+ is provided on the HTML element. This is appropriate for
+ widgets such as `Records` and `Facet` that display some part
+ of a search result.
+
+* `VOID hideWhenNarrow()` --
+ Registers that this widget should hide itself when the page
+ becomes "narrow" -- that is, fewer pixels in width that the
+ threshhold value specified by the top-level configuration item
+ `responsive_design_width`. Should be used for "unimportant"
+ widgets that can be omitted from the mobile version of a site.
+
+* `expandValue()` --
+ TODO: either document this or remove it from the API.
+
+* `subwidget(type, overrides, defaults)` --
+ Returns the HTML of a subwidget of the specified type, which
+ can then be inserted into the widget using the
+ `this.node.html` function. The subwidget is given the same
+ attributes at the parent widget that invokes this function,
+ except where overrides are passed in. If defaults are also
+ provided, then these are used when the parent widget provides
+ no values. Both the `overrides` and `defaults` arguments are
+ hashes: the latter is optional.
+
+ See for example the `Credo` widget defined in the example
+ area's `mkws-widget-credo.js` file. This uses several
+ invocations of `subwidget` to create a complex compound widget
+ with numerous text, facet and image panes. TODO: rename this
+ widget and everything related to it.
+
+In addition to these properties and methods of the bare widget object,
+some kinds of specific widget add other properties of their own. For
+example, the `Builder` widget uses a `callback` property as the
+function that it use to publish the widget definition that it
+constructs. This defaults to the builtin function `alert`, but can be
+overridden by derived widgets such as `ConsoleBuilder`.
+
+
+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()
+* `String team.name()`
+* `Bool team.submitted()`
+* `Num team.perpage()`
+* `Num team.totalRecordCount()`
+* `Num team.currentPage();`
+* `String team.currentRecordId()`
+* `String team.currentRecordData()`
+
+These are all 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.
+ convenient to do it this way. If you must insist on using
+ this, see the `Navi` widget, which is the only place it's used.
-Hash team.config()
+* `Bool team.targetFiltered(targetId)` --
+ Indicates whether the specified target has been filtered by
+ selection as a facet. This is used only by the `Facet` widget,
+ and there is probably no reason for you to use it.
+
+* `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.
+ been overridden are accessible via `this.config`.
-Void team.set_sortOrder(string)
-Void team.set_perpage(number)
+* `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.
+ functions. Unlikely to be needed outside of the `Sort` and
+ `Perpage` widgets.
-Queue team.queue(eventName)
+* `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)
+* `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()
+* `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)
+* `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)
+* `String team.renderDetails(recordData)` --
Utility function returns an HTML rendering of the record
represented by the specified data.
-Template team.loadTemplate(templateName)
+* `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.
widgets is still in the team. When we finish migrating it, the widget
API should get simpler.
+
+Events
+------
+
+TODO: list of events that can be usefully subscribed to.
+
+
+- - -
+
+Copyright (C) 2013-2014 by IndexData ApS, <http://www.indexdata.com>
projects / mkws-moved-to-github.git / blobdiff