Fix for aggregate functions applied to empty sets (#964)

* Return undefined from aggregate functions when the accumulator is undefined (fixes #917)

* Build from src

Author: alexpeattie

dist/alasql-worker.js

@@ -1,7 +1,7 @@
-//! AlaSQL v0.4.4 | © 2014-2016 Andrey Gershun & Mathias Rangel Wulff | License: MIT 
+//! AlaSQL v0.4.4-fix-aggregate-empty-sets-1566 | © 2014-2016 Andrey Gershun & Mathias Rangel Wulff | License: MIT 
 /*
 @module alasql
-@version 0.4.4
+@version 0.4.4-fix-aggregate-empty-sets-1566
 
 AlaSQL - JavaScript SQL database
 © 2014-2016	Andrey Gershun & Mathias Rangel Wulff

dist/alasql-worker.min.js

@@ -1,7 +1,7 @@
-//! AlaSQL v0.4.4 | © 2014-2016 Andrey Gershun & Mathias Rangel Wulff | License: MIT 
+//! AlaSQL v0.4.4-fix-aggregate-empty-sets-1566 | © 2014-2016 Andrey Gershun & Mathias Rangel Wulff | License: MIT 
 /*
 @module alasql
-@version 0.4.4
+@version 0.4.4-fix-aggregate-empty-sets-1566
 
 AlaSQL - JavaScript SQL database
 © 2014-2016	Andrey Gershun & Mathias Rangel Wulff
@@ -137,7 +137,7 @@ var alasql = function(sql, params, cb, scope) {
 	Current version of alasql 
  	@constant {string} 
 */
-alasql.version = '0.4.4';
+alasql.version = '0.4.4-fix-aggregate-empty-sets-1566';
 
 /**
 	Debug flag
@@ -10832,6 +10832,15 @@ alasql.aggr.STD = alasql.aggr.STDDEV = alasql.aggr.STDEVP = function(v,s,stage){
 	}
 };
 
+alasql._aggrOriginal = alasql.aggr
+alasql.aggr = {}
+Object.keys(alasql._aggrOriginal).forEach(function(k) {
+	alasql.aggr[k] = function(v, s, stage) {
+		if(stage === 3 && typeof(s) === 'undefined') return undefined;
+		return alasql._aggrOriginal[k].apply(null, arguments)
+	}
+})
+
 // String functions
 stdfn.REPLACE = function (target,pattern,replacement) {
     return (target||'').split(pattern).join(replacement);

dist/alasql.fs.js

@@ -1,7 +1,7 @@
-//! AlaSQL v0.4.4 | © 2014-2016 Andrey Gershun & Mathias Rangel Wulff | License: MIT 
+//! AlaSQL v0.4.4-fix-aggregate-empty-sets-1566 | © 2014-2016 Andrey Gershun & Mathias Rangel Wulff | License: MIT 
 /*
 @module alasql
-@version 0.4.4
+@version 0.4.4-fix-aggregate-empty-sets-1566
 
 AlaSQL - JavaScript SQL database
 © 2014-2016	Andrey Gershun & Mathias Rangel Wulff
@@ -137,7 +137,7 @@ var alasql = function(sql, params, cb, scope) {
 	Current version of alasql 
  	@constant {string} 
 */
-alasql.version = '0.4.4';
+alasql.version = '0.4.4-fix-aggregate-empty-sets-1566';
 
 /**
 	Debug flag
@@ -10832,6 +10832,15 @@ alasql.aggr.STD = alasql.aggr.STDDEV = alasql.aggr.STDEVP = function(v,s,stage){
 	}
 };
 
+alasql._aggrOriginal = alasql.aggr
+alasql.aggr = {}
+Object.keys(alasql._aggrOriginal).forEach(function(k) {
+	alasql.aggr[k] = function(v, s, stage) {
+		if(stage === 3 && typeof(s) === 'undefined') return undefined;
+		return alasql._aggrOriginal[k].apply(null, arguments)
+	}
+})
+
 // String functions
 stdfn.REPLACE = function (target,pattern,replacement) {
     return (target||'').split(pattern).join(replacement);

dist/alasql.js

@@ -387,6 +387,15 @@ alasql.aggr.STD = alasql.aggr.STDDEV = alasql.aggr.STDEVP = function(v,s,stage){
 	}
 };
 
+alasql._aggrOriginal = alasql.aggr
+alasql.aggr = {}
+Object.keys(alasql._aggrOriginal).forEach(function(k) {
+	alasql.aggr[k] = function(v, s, stage) {
+		if(stage === 3 && typeof(s) === 'undefined') return undefined;
+		return alasql._aggrOriginal[k].apply(null, arguments)
+	}
+})
+
 // String functions
 stdfn.REPLACE = function (target,pattern,replacement) {
     return (target||'').split(pattern).join(replacement);

dist/alasql.min.js

@@ -0,0 +1,26 @@
+if(typeof exports === 'object') {
+  var assert = require("assert");
+  var alasql = require('..');
+};
+
+/*
+  Test for issue #917
+*/
+
+var test = 619;
+
+describe('Test '+test+' calling aggregate functions on empty sets', function() {
+
+  before(function(){
+    alasql('CREATE DATABASE test'+test+';USE test'+test);
+  });
+
+  after(function(){
+    alasql('DROP DATABASE test'+test);
+  });
+
+  it('1. Should always return undefined', function(){
+    res = alasql('SELECT STDDEV(col) AS Result FROM ? WHERE 1=0', [[{col:1},{col:2}]]);
+    assert.equal(res[0]['Result'], undefined);
+  })
+});