YUI Library Examples: DataSource Utility: YQLDataSource

The YQLDataSource constructor does not require any parameters. It automatically uses the Get utility, a required dependency, to access the YQL servers and retrieve JSON data into a callback. The YQLDataSource just needs to be instantiated like this:

There is no need to indicate the server, responseType, or responseSchema, which will all be defined for you. The responseType will always be of type JSON and the responseSchema.resultsList will always point to the very first repeating element under query.results.

To integrate with DataTable, the YQL query string has been set in the initialRequest configuration attribute. All returned fields of all returned results will be copied to the in-memory RecordSet, so care should be taken accessing queries whose results may require a lot of memory.

The YQL response itself provides no indication of the data type of the individual fields at this time. So by default, all fields will be read as strings, but if any field needs to be parsed, you can specify those fields in the usual responseSchema.fields = [ ..., {key:"xxxx",parser:"date"},...] manner. Actually, all fields in the result set will be parsed, so you only really need to specify those that need a parser -- all the rest will be added to the fields array and read as strings automatically.

The YQLDataSource class extends the ScriptNodeDataSource class:

YAHOO.util.YQLDataSource = function (oLiveData, oConfigs) {
	oLiveData = oLiveData || 'http://query.yahooapis.com/v1/public/yql?format=json&q=';
	YAHOO.util.YQLDataSource.superclass.constructor.call(this, oLiveData, oConfigs);
};

YAHOO.lang.extend(YAHOO.util.YQLDataSource, YAHOO.util.ScriptNodeDataSource, {
	responseType:YAHOO.util.DataSource.TYPE_JSON,
	parseJSONData: function  ( oRequest , oFullResponse ) {
		var i,q = oFullResponse.query.results,
			rSch = this.responseSchema,
			fs = {};

if ('fields' in rSch  && rSch.fields.length) {
			for (i = 0;i < rSch.fields.length;i++) {
				fs[rSch.fields[i].key || rSch.fields[i]] = i;
			}
		} else {
			rSch.fields = [];
		}
		var pushFields = function(node,prefix) {
			if (prefix) {
				prefix += '.';
			} else {
				prefix = '';
			}
			for (var field in node) {
				if (node.hasOwnProperty(field) && !(field in fs)) {
					if (YAHOO.lang.isObject(node[field])) {
						pushFields(node[field],prefix + field);
					} else {
						rSch.fields.push(prefix + field);
					}
				}
			}
		};

for (var list in q) {
			if (q.hasOwnProperty(list)) {
				rSch.resultsList = rSch.resultsList || 'query.results.' + list;
				pushFields(q[list][0]);
				return YAHOO.util.YQLDataSource.superclass.parseJSONData.apply(this,arguments);
			}
		}
	},
	makeConnection : function(oRequest, oCallback, oCaller) {
		YAHOO.util.YQLDataSource.superclass.makeConnection.call(this,encodeURIComponent(oRequest),oCallback,oCaller);
	}
});

YAHOO.lang.augmentObject(YAHOO.util.YQLDataSource, YAHOO.util.DataSourceBase);

Once the YQLDataSource class definition has been loaded, you can add code to create the DataTable:

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DataSource Utility Examples:

More DataSource Utility Resources:

API Documentation

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