Example: Recordset Filter Plugin

The filter plugin allows operations to filter a Recordset instance. All the methods generate new Recordsets that are subsets of the original Recordset.

Using the Plugin

• Filter by key/value
• Using custom filter functions
• Other ways to filter

The RecordsetFilter plugin supports filtering a Recordset instance using a custom filter function, or key/value pairs.

YUI().use("recordset-base", "recordset-filter", function(Y) {
    var state_census_data = [
        {ANSI: "01000", STATE: "ALABAMA", TOTAL_POP: 4708708, LAND_AREA: 50744, POP_PER_SQ_MILE: 87.6},
        {ANSI: "06000", STATE: "CALIFORNIA", TOTAL_POP: 36961664, LAND_AREA: 155959.34, POP_PER_SQ_MILE: 217.2},
        {ANSI: "10000", STATE: "DELAWARE", TOTAL_POP: 885122, LAND_AREA: 1953.56, POP_PER_SQ_MILE: 401}
    ],
	
	//instantiate a new Recordset
	recordset = new Y.Recordset({records: state_census_data});
	
	//Plug it with the Filter plugin
	recordset.plug(Y.Plugin.RecordsetFilter);
	
	//call filter methods with the 'filter' namespace
	var subset = recordset.filter.filter("STATE", "CALIFORNIA");
});

Filtering by Key/Value

The filter() method can take a key as its first argument, and a value as its second. Doing so will return a subset of the original Recordset, with records that match the specific key/value pair.

//call filter methods with the 'filter' namespace
var subset = recordset.filter.filter("STATE", "CALIFORNIA");

Filtering by Custom Function

Additionally, a custom function can be passed in to the filter method. In this scenario, all records will be evaluated against this function, and if a truthy value is returned, it will be pushed onto the returning sub-Recordset.

var myCustomFilterFunction = function(item) {
	var letter = item.getValue('STATE').charAt(0);
	if (letter === 'M' || letter === 'N' || letter === 'O' || letter === 'P') {
		return true;
	}
	else {
		return false;
	}
};

//All records which have a STATE property starting with "M", "N", "O", or "P" will be pushed onto the new Recordset.
var subset = recordset.filter.filter(myCustomFilterFunction);

Other Ways to Filter

As Recordset augments Y.Arraylist, methods from the array-extras sub-module can be used. Currently, the RecordsetFilter plugin supports reject() and grep(). However, using other methods from the array-extras utility is straight-forward:

//use the 'array-extras' submodule
YUI().use("recordset-base", "recordset-filter", "array-extras", function(Y) {
	
    var state_census_data = [
        {ANSI: "01000", STATE: "ALABAMA", TOTAL_POP: 4708708, LAND_AREA: 50744, POP_PER_SQ_MILE: 87.6},
        {ANSI: "06000", STATE: "CALIFORNIA", TOTAL_POP: 36961664, LAND_AREA: 155959.34, POP_PER_SQ_MILE: 217.2},
        {ANSI: "10000", STATE: "DELAWARE", TOTAL_POP: 885122, LAND_AREA: 1953.56, POP_PER_SQ_MILE: 401}
	],
	//instantiate a new Recordset
	recordset = new Y.Recordset({records: state_census_data});
	
	//Define a custom function
	customFindFunction = function() {
		...
	}
	
	//Use the Array.find method found in the array-extras sub-module
	var subset = new Y.Recordset({
	       records: Y.Array.find(recordset.get('records'), customFindFunction)
	});
});