dataview.aggregators.js

define(function () {

	function AvgAggregator(field) {
		this.field_ = field;

		this.init = function () {
			this.count_ = 0;
			this.nonNullCount_ = 0;
			this.sum_ = 0;
		};

		this.accumulate = function (item) {
			var val = item[this.field_];
			this.count_ ++;
			if (val != null && val != "" && val != NaN) {
				this.nonNullCount_ ++;
				this.sum_ += parseFloat(val);
			}
		};

		this.storeResult = function (groupTotals) {
			if (! groupTotals.avg) {
				groupTotals.avg = {};
			}
			if (this.nonNullCount_ != 0) {
				groupTotals.avg[this.field_] = this.sum_ / this.nonNullCount_;
			}
		};
	}

	function MinAggregator(field) {
		this.field_ = field;

		this.init = function () {
			this.min_ = null;
		};

		this.accumulate = function (item) {
			var val = item[this.field_];
			if (val != null && val != "" && val != NaN) {
				if (this.min_ == null || val < this.min_) {
					this.min_ = val;
				}
			}
		};

		this.storeResult = function (groupTotals) {
			if (! groupTotals.min) {
				groupTotals.min = {};
			}
			groupTotals.min[this.field_] = this.min_;
		}
	}

	function MaxAggregator(field) {
		this.field_ = field;

		this.init = function () {
			this.max_ = null;
		};

		this.accumulate = function (item) {
			var val = item[this.field_];
			if (val != null && val != "" && val != NaN) {
				if (this.max_ == null || val > this.max_) {
					this.max_ = val;
				}
			}
		};

		this.storeResult = function (groupTotals) {
			if (! groupTotals.max) {
				groupTotals.max = {};
			}
			groupTotals.max[this.field_] = this.max_;
		}
	}

	function SumAggregator(field) {
		this.field_ = field;

		this.init = function () {
			this.sum_ = null;
		};

		this.accumulate = function (item) {
			var val = item[this.field_];
			if (val != null && val != "" && val != NaN) {
				this.sum_ += parseFloat(val);
			}
		};

		this.storeResult = function (groupTotals) {
			if (! groupTotals.sum) {
				groupTotals.sum = {};
			}
			groupTotals.sum[this.field_] = this.sum_;
		}
	}

	// TODO:  add more built-in aggregators
	// TODO:  merge common aggregators in one to prevent needles iterating

	return {
		Avg: AvgAggregator,
		Min: MinAggregator,
		Max: MaxAggregator,
		Sum: SumAggregator
	};

});