fixes #340 - "none" value set to null, formatValueToField checks fo…

…r `isNil(value)` and returns `null`, none options are always disabled

* updated tests to reflect "none is always disabled", could possibly be a selectOptions to allow users to select the "none" option to clear a previously selected value?
* added formatValueToField and return `null` when `isNil(value)`

src/fields/core/fieldSelect.vue

@@ -1,6 +1,6 @@
 <template lang="pug">
 	select.form-control(v-model="value", :disabled="disabled", :name="schema.inputName", :id="getFieldID(schema)", :class="schema.fieldClasses")
-		option(v-if="!selectOptions.hideNoneSelectedText", :disabled="schema.required", :value="null", :selected="value == undefined") {{ selectOptions.noneSelectedText || "&lt;Nothing selected&gt;" }}
+		option(v-if="!selectOptions.hideNoneSelectedText", :disabled="true", :value="null") {{ selectOptions.noneSelectedText || "&lt;Nothing selected&gt;" }}
 
 		template(v-for="item in items")
 			optgroup(v-if="item.group", :label="getGroupName(item)")
@@ -10,7 +10,7 @@
 </template>
 
 <script>
-	import {isObject, find} from "lodash";
+	import {isObject, isNil, find} from "lodash";
 	import abstractField from "../abstractField";
 	
 	export default {
@@ -27,10 +27,16 @@
 					return this.groupValues(values.apply(this, [this.model, this.schema]));
 				} else
 					return this.groupValues(values);
-			}
+			},
 		},
 
 		methods: {
+			formatValueToField(value) {
+				if(isNil(value)) {
+					return null;
+				}
+				return value;
+			},
 
 			groupValues(values){
 				let array = [];
@@ -123,7 +129,7 @@
 				} else {
 					return item;
 				}
-			}
+			},
 		}
 	};
 </script>

test/unit/specs/fields/fieldSelect.spec.js

@@ -56,7 +56,8 @@ describe("fieldSelect.vue", function () {
 
 		it("should contain a <non selected> element", () => {
 			let options = input.querySelectorAll("option");
-			expect(options[0].disabled).to.be.false;
+			// "none selected" options are always disabled
+			expect(options[0].disabled).to.be.true;
 			expect(options[0].textContent).to.be.equal("<Nothing selected>");
 		});