/**
* DataView
*
* a dataview offers a filtered view on a dataset or an other dataview.
*
* @param {DataSet | DataView} data
* @param {Object} [options] Available options: see method get
*
* @constructor DataView
*/
function DataView (data, options) {
this.id = util.randomUUID();
this.data = null;
this.ids = {}; // ids of the items currently in memory (just contains a boolean true)
this.options = options || {};
this.fieldId = 'id'; // name of the field containing id
this.subscribers = {}; // event subscribers
var me = this;
this.listener = function () {
me._onEvent.apply(me, arguments);
};
this.setData(data);
}
/**
* Set a data source for the view
* @param {DataSet | DataView} data
*/
DataView.prototype.setData = function (data) {
var ids, dataItems, i, len;
if (this.data) {
// unsubscribe from current dataset
if (this.data.unsubscribe) {
this.data.unsubscribe('*', this.listener);
}
// trigger a remove of all items in memory
ids = [];
for (var id in this.ids) {
if (this.ids.hasOwnProperty(id)) {
ids.push(id);
}
}
this.ids = {};
this._trigger('remove', {items: ids});
}
this.data = data;
if (this.data) {
// update fieldId
this.fieldId = this.options.fieldId ||
(this.data && this.data.options && this.data.options.fieldId) ||
'id';
// trigger an add of all added items
ids = this.data.getIds({filter: this.options && this.options.filter});
for (i = 0, len = ids.length; i < len; i++) {
id = ids[i];
this.ids[id] = true;
}
this._trigger('add', {items: ids});
// subscribe to new dataset
if (this.data.subscribe) {
this.data.subscribe('*', this.listener);
}
}
};
/**
* Get data from the data view
*
* Usage:
*
* get()
* get(options: Object)
* get(options: Object, data: Array | DataTable)
*
* get(id: Number)
* get(id: Number, options: Object)
* get(id: Number, options: Object, data: Array | DataTable)
*
* get(ids: Number[])
* get(ids: Number[], options: Object)
* get(ids: Number[], options: Object, data: Array | DataTable)
*
* Where:
*
* {Number | String} id The id of an item
* {Number[] | String{}} ids An array with ids of items
* {Object} options An Object with options. Available options:
* {String} [type] Type of data to be returned. Can
* be 'DataTable' or 'Array' (default)
* {Object.<String, String>} [convert]
* {String[]} [fields] field names to be returned
* {function} [filter] filter items
* {String | function} [order] Order the items by
* a field name or custom sort function.
* {Array | DataTable} [data] If provided, items will be appended to this
* array or table. Required in case of Google
* DataTable.
* @param args
*/
DataView.prototype.get = function (args) {
var me = this;
// parse the arguments
var ids, options, data;
var firstType = util.getType(arguments[0]);
if (firstType == 'String' || firstType == 'Number' || firstType == 'Array') {
// get(id(s) [, options] [, data])
ids = arguments[0]; // can be a single id or an array with ids
options = arguments[1];
data = arguments[2];
}
else {
// get([, options] [, data])
options = arguments[0];
data = arguments[1];
}
// extend the options with the default options and provided options
var viewOptions = util.extend({}, this.options, options);
// create a combined filter method when needed
if (this.options.filter && options && options.filter) {
viewOptions.filter = function (item) {
return me.options.filter(item) && options.filter(item);
}
}
// build up the call to the linked data set
var getArguments = [];
if (ids != undefined) {
getArguments.push(ids);
}
getArguments.push(viewOptions);
getArguments.push(data);
return this.data && this.data.get.apply(this.data, getArguments);
};
/**
* Get ids of all items or from a filtered set of items.
* @param {Object} [options] An Object with options. Available options:
* {function} [filter] filter items
* {String | function} [order] Order the items by
* a field name or custom sort function.
* @return {Array} ids
*/
DataView.prototype.getIds = function (options) {
var ids;
if (this.data) {
var defaultFilter = this.options.filter;
var filter;
if (options && options.filter) {
if (defaultFilter) {
filter = function (item) {
return defaultFilter(item) && options.filter(item);
}
}
else {
filter = options.filter;
}
}
else {
filter = defaultFilter;
}
ids = this.data.getIds({
filter: filter,
order: options && options.order
});
}
else {
ids = [];
}
return ids;
};
/**
* Event listener. Will propagate all events from the connected data set to
* the subscribers of the DataView, but will filter the items and only trigger
* when there are changes in the filtered data set.
* @param {String} event
* @param {Object | null} params
* @param {String} senderId
* @private
*/
DataView.prototype._onEvent = function (event, params, senderId) {
var i, len, id, item,
ids = params && params.items,
data = this.data,
added = [],
updated = [],
removed = [];
if (ids && data) {
switch (event) {
case 'add':
// filter the ids of the added items
for (i = 0, len = ids.length; i < len; i++) {
id = ids[i];
item = this.get(id);
if (item) {
this.ids[id] = true;
added.push(id);
}
}
break;
case 'update':
// determine the event from the views viewpoint: an updated
// item can be added, updated, or removed from this view.
for (i = 0, len = ids.length; i < len; i++) {
id = ids[i];
item = this.get(id);
if (item) {
if (this.ids[id]) {
updated.push(id);
}
else {
this.ids[id] = true;
added.push(id);
}
}
else {
if (this.ids[id]) {
delete this.ids[id];
removed.push(id);
}
else {
// nothing interesting for me :-(
}
}
}
break;
case 'remove':
// filter the ids of the removed items
for (i = 0, len = ids.length; i < len; i++) {
id = ids[i];
if (this.ids[id]) {
delete this.ids[id];
removed.push(id);
}
}
break;
}
if (added.length) {
this._trigger('add', {items: added}, senderId);
}
if (updated.length) {
this._trigger('update', {items: updated}, senderId);
}
if (removed.length) {
this._trigger('remove', {items: removed}, senderId);
}
}
};
// copy subscription functionality from DataSet
DataView.prototype.subscribe = DataSet.prototype.subscribe;
DataView.prototype.unsubscribe = DataSet.prototype.unsubscribe;
DataView.prototype._trigger = DataSet.prototype._trigger;