saving csv created faulty content with horizontal list columns (#279)

* saving csv created faulty content with horizontal list columns

* Added fix for save as xlsx

* Fixed order of mixins, refactored so column list mixin does work and nullcheckfilter added

Author: JockeCK

cosmoz-omnitable-column-list-horizontal.html

@@ -56,7 +56,7 @@
 		 * @appliesMixin Cosmoz.OmnitableColumnMixin
 		 * @appliesMixin Cosmoz.ListColumnMixin
 		 */
-		class OmnitableColumnListHorizontal extends	Cosmoz.OmnitableColumnMixin(Cosmoz.ListColumnMixin(
+		class OmnitableColumnListHorizontal extends	Cosmoz.ListColumnMixin(Cosmoz.OmnitableColumnMixin(
 			Polymer.mixinBehaviors([Cosmoz.TranslatableBehavior], Polymer.Element)
 		)) {
 			static get is() {
@@ -145,13 +145,8 @@
 				return [];
 			}
 
-			getString() {
-				const value = super.getString.apply(this, arguments);
-				if (!Array.isArray(value) || value.length === 0) {
-					return '';
-				}
-
-				return value.join(', ');
+			toXlsxValue(item, valuePath = this.valuePath) {
+				return this.getString(item, valuePath);
 			}
 		}
 

cosmoz-omnitable-column-list-mixin.html

@@ -33,6 +33,7 @@
 			return values
 				.map(value => this.textProperty ? this.get(this.textProperty, value) : value)
 				.filter((value, index, array) => array.indexOf(value) === index)
+				.filter(Boolean)
 				.join(', ');
 		}
 	});