mungedb-aggregate/lib/pipeline/expressions/DayOfMonthExpression.js

"use strict";

/**
 * Get the DayOfMonth from a date.
 * @class DayOfMonthExpression
 * @namespace mungedb-aggregate.pipeline.expressions
 * @module mungedb-aggregate
 * @constructor
 **/
var DayOfMonthExpression = module.exports = function DayOfMonthExpression() {
		this.fixedArity(1);
		if (arguments.length !== 1) throw new Error("one args expected");
		base.call(this);
}, klass = DayOfMonthExpression,
		base = require("./NaryExpression"),
		proto = klass.prototype = Object.create(base.prototype, {
				constructor: {
						value: klass
				}
		});

// DEPENDENCIES
var Expression = require("./Expression");

// PROTOTYPE MEMBERS
proto.getOpName = function getOpName() {
		return "$dayOfMonth";
};

/**
 * Takes a date and returns the day of the month as a number between 1 and 31.
 * @method evaluate
 **/
proto.evaluateInternal = function evaluateInternal(doc) {
		var date = this.operands[0].evaluateInternal(doc);
		return date.getUTCDate();
};

/** Register Expression */
Expression.registerExpression("$dayOfMonth", DayOfMonthExpression.parse);