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390 lines
10 KiB
390 lines
10 KiB
var util = require('./util');
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var DataSet = require('./DataSet');
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/**
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* DataView
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*
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* a dataview offers a filtered view on a dataset or an other dataview.
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*
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* @param {DataSet | DataView} data
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* @param {Object} [options] Available options: see method get
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*
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* @constructor DataView
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*/
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function DataView (data, options) {
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this._data = null;
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this._ids = {}; // ids of the items currently in memory (just contains a boolean true)
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this.length = 0; // number of items in the DataView
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this._options = options || {};
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this._fieldId = 'id'; // name of the field containing id
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this._subscribers = {}; // event subscribers
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var me = this;
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this.listener = function () {
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me._onEvent.apply(me, arguments);
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};
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this.setData(data);
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}
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// TODO: implement a function .config() to dynamically update things like configured filter
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// and trigger changes accordingly
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/**
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* Set a data source for the view
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* @param {DataSet | DataView} data
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*/
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DataView.prototype.setData = function (data) {
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var ids, id, i, len;
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if (this._data) {
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// unsubscribe from current dataset
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if (this._data.off) {
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this._data.off('*', this.listener);
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}
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// trigger a remove of all items in memory
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ids = Object.keys(this._ids);
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this._ids = {};
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this.length = 0;
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this._trigger('remove', {items: ids});
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}
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this._data = data;
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if (this._data) {
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// update fieldId
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this._fieldId = this._options.fieldId ||
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(this._data && this._data.options && this._data.options.fieldId) ||
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'id';
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// trigger an add of all added items
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ids = this._data.getIds({filter: this._options && this._options.filter});
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for (i = 0, len = ids.length; i < len; i++) {
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id = ids[i];
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this._ids[id] = true;
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}
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this.length = ids.length;
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this._trigger('add', {items: ids});
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// subscribe to new dataset
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if (this._data.on) {
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this._data.on('*', this.listener);
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}
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}
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};
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/**
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* Refresh the DataView. Useful when the DataView has a filter function
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* containing a variable parameter.
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*/
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DataView.prototype.refresh = function () {
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var id, i, len;
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var ids = this._data.getIds({filter: this._options && this._options.filter});
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var oldIds = Object.keys(this._ids);
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var newIds = {};
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var added = [];
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var removed = [];
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// check for additions
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for (i = 0, len = ids.length; i < len; i++) {
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id = ids[i];
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newIds[id] = true;
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if (!this._ids[id]) {
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added.push(id);
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this._ids[id] = true;
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}
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}
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// check for removals
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for (i = 0, len = oldIds.length; i < len; i++) {
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id = oldIds[i];
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if (!newIds[id]) {
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removed.push(id);
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delete this._ids[id];
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}
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}
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this.length += added.length - removed.length;
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// trigger events
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if (added.length) {
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this._trigger('add', {items: added});
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}
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if (removed.length) {
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this._trigger('remove', {items: removed});
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}
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};
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/**
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* Get data from the data view
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*
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* Usage:
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*
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* get()
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* get(options: Object)
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* get(options: Object, data: Array | DataTable)
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*
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* get(id: Number)
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* get(id: Number, options: Object)
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* get(id: Number, options: Object, data: Array | DataTable)
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*
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* get(ids: Number[])
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* get(ids: Number[], options: Object)
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* get(ids: Number[], options: Object, data: Array | DataTable)
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*
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* Where:
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*
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* {Number | String} id The id of an item
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* {Number[] | String{}} ids An array with ids of items
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* {Object} options An Object with options. Available options:
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* {String} [type] Type of data to be returned. Can
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* be 'DataTable' or 'Array' (default)
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* {Object.<String, String>} [convert]
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* {String[]} [fields] field names to be returned
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* {function} [filter] filter items
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* {String | function} [order] Order the items by
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* a field name or custom sort function.
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* {Array | DataTable} [data] If provided, items will be appended to this
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* array or table. Required in case of Google
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* DataTable.
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* @param args
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*/
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DataView.prototype.get = function (args) {
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var me = this;
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// parse the arguments
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var ids, options, data;
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var firstType = util.getType(arguments[0]);
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if (firstType == 'String' || firstType == 'Number' || firstType == 'Array') {
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// get(id(s) [, options] [, data])
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ids = arguments[0]; // can be a single id or an array with ids
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options = arguments[1];
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data = arguments[2];
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}
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else {
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// get([, options] [, data])
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options = arguments[0];
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data = arguments[1];
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}
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// extend the options with the default options and provided options
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var viewOptions = util.extend({}, this._options, options);
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// create a combined filter method when needed
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if (this._options.filter && options && options.filter) {
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viewOptions.filter = function (item) {
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return me._options.filter(item) && options.filter(item);
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}
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}
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// build up the call to the linked data set
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var getArguments = [];
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if (ids != undefined) {
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getArguments.push(ids);
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}
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getArguments.push(viewOptions);
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getArguments.push(data);
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return this._data && this._data.get.apply(this._data, getArguments);
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};
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/**
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* Get ids of all items or from a filtered set of items.
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* @param {Object} [options] An Object with options. Available options:
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* {function} [filter] filter items
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* {String | function} [order] Order the items by
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* a field name or custom sort function.
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* @return {Array} ids
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*/
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DataView.prototype.getIds = function (options) {
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var ids;
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if (this._data) {
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var defaultFilter = this._options.filter;
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var filter;
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if (options && options.filter) {
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if (defaultFilter) {
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filter = function (item) {
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return defaultFilter(item) && options.filter(item);
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}
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}
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else {
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filter = options.filter;
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}
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}
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else {
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filter = defaultFilter;
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}
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ids = this._data.getIds({
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filter: filter,
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order: options && options.order
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});
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}
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else {
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ids = [];
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}
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return ids;
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};
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/**
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* Map every item in the dataset.
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* @param {function} callback
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* @param {Object} [options] Available options:
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* {Object.<String, String>} [type]
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* {String[]} [fields] filter fields
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* {function} [filter] filter items
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* {String | function} [order] Order the items by
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* a field name or custom sort function.
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* @return {Object[]} mappedItems
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*/
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DataView.prototype.map = function (callback,options) {
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var mappedItems = [];
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if (this._data) {
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var defaultFilter = this._options.filter;
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var filter;
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if (options && options.filter) {
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if (defaultFilter) {
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filter = function (item) {
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return defaultFilter(item) && options.filter(item);
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}
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}
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else {
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filter = options.filter;
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}
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}
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else {
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filter = defaultFilter;
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}
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mappedItems = this._data.map(callback,{
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filter: filter,
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order: options && options.order
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});
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}
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else {
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mappedItems = [];
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}
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return mappedItems;
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};
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/**
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* Get the DataSet to which this DataView is connected. In case there is a chain
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* of multiple DataViews, the root DataSet of this chain is returned.
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* @return {DataSet} dataSet
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*/
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DataView.prototype.getDataSet = function () {
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var dataSet = this;
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while (dataSet instanceof DataView) {
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dataSet = dataSet._data;
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}
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return dataSet || null;
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};
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/**
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* Event listener. Will propagate all events from the connected data set to
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* the subscribers of the DataView, but will filter the items and only trigger
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* when there are changes in the filtered data set.
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* @param {String} event
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* @param {Object | null} params
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* @param {String} senderId
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* @private
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*/
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DataView.prototype._onEvent = function (event, params, senderId) {
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var i, len, id, item;
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var ids = params && params.items;
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var data = this._data;
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var updatedData = [];
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var oldData = [];
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var added = [];
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var updated = [];
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var removed = [];
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if (ids && data) {
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switch (event) {
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case 'add':
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// filter the ids of the added items
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for (i = 0, len = ids.length; i < len; i++) {
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id = ids[i];
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item = this.get(id);
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if (item) {
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this._ids[id] = true;
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added.push(id);
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}
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}
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break;
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case 'update':
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// determine the event from the views viewpoint: an updated
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// item can be added, updated, or removed from this view.
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for (i = 0, len = ids.length; i < len; i++) {
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id = ids[i];
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item = this.get(id);
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if (item) {
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if (this._ids[id]) {
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updated.push(id);
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updatedData.push(params.data[i]);
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oldData.push(params.oldData[i]);
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}
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else {
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this._ids[id] = true;
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added.push(id);
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}
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}
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else {
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if (this._ids[id]) {
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delete this._ids[id];
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removed.push(id);
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}
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else {
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// nothing interesting for me :-(
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}
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}
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}
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break;
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case 'remove':
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// filter the ids of the removed items
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for (i = 0, len = ids.length; i < len; i++) {
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id = ids[i];
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if (this._ids[id]) {
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delete this._ids[id];
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removed.push(id);
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}
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}
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break;
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}
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this.length += added.length - removed.length;
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if (added.length) {
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this._trigger('add', {items: added}, senderId);
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}
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if (updated.length) {
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this._trigger('update', {items: updated, data: updatedData, oldData: oldData}, senderId);
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}
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if (removed.length) {
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this._trigger('remove', {items: removed}, senderId);
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}
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}
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};
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// copy subscription functionality from DataSet
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DataView.prototype.on = DataSet.prototype.on;
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DataView.prototype.off = DataSet.prototype.off;
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DataView.prototype._trigger = DataSet.prototype._trigger;
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// TODO: make these functions deprecated (replaced with `on` and `off` since version 0.5)
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DataView.prototype.subscribe = DataView.prototype.on;
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DataView.prototype.unsubscribe = DataView.prototype.off;
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module.exports = DataView;
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