Fix DateTime attribute field value does not get rendered on Entity ed…

…it (#202)

frontend/src/components/inputs/DateTime.vue

@@ -1,7 +1,9 @@
 <template>
   <BaseInput :label="label" :args="args" :vertical="vertical" :required="required">
     <template v-slot:field>
-      <input class="form-control" type="datetime-local" :value="modelValue" @input="onInput"
+      <input class="form-control" type="datetime-local"
+             :value="value"
+             @input="onInput"
              v-bind="args"/>
     </template>
   </BaseInput>
@@ -14,10 +16,22 @@ export default {
   name: "DateTime",
   components: {BaseInput},
   props: ["label", "modelValue", "args", "vertical", "required"],
+  computed: {
+    value() {
+      return this.modelValue && this.convertToDateTimeLocalString(this.modelValue);
+    }
+  },
   methods: {
     onInput(event) {
       this.$emit("update:modelValue", event.target.value);
     },
+    convertToDateTimeLocalString(date) {
+      if (!(date instanceof Date)) {
+        date = new Date(date)
+      }
+
+      return date.toISOString().substring(0, 16);
+    }
   },
 };
 </script>