Display optional blank node as list (#194)

* add isOptionalBlankNode to fieldUtils

* use isOptionalBlankNode in FormRenderer.isList

  this is ugly, but is the least invasive way to do it

  we could rename isList to something more fitting

* do not add default fields in case of optional blank node

* simplify condition for createDefaultValueArray by using isOptionalBlankNode

* rename isOptionalBlankNode to isOptionalNode

* check for sh:NodeShape instead of dash:BlankNodeEditor in isOptionalNode()

Author: dennisvang

src/components/ShaclForm/FormRenderer.vue

@@ -135,7 +135,7 @@ export default class FormRenderer extends Vue {
   }
 
   createDefaultValueArray(field) {
-    if (field.minCount === 1 || field.maxCount === 1) {
+    if (field.minCount === 1 || (field.maxCount === 1 && !fieldUtils.isOptionalNode(field))) {
       return [this.createDefaultValue(field)]
     }
 
@@ -162,7 +162,7 @@ export default class FormRenderer extends Vue {
   }
 
   isList(field) {
-    return fieldUtils.isList(field)
+    return fieldUtils.isList(field) || fieldUtils.isOptionalNode(field)
   }
 
   canBeRemoved(field) {

src/components/ShaclForm/fieldUtils.ts

@@ -33,6 +33,10 @@ function isRequired(field: FormField): boolean {
   return field.minCount > 0
 }
 
+function isOptionalNode(field: FormField): boolean {
+  return field.nodeShape && !field.minCount && field.maxCount === 1
+}
+
 function isBoolean(field: FormField): boolean {
   return field.datatype === XSD('boolean').value
 }
@@ -61,6 +65,7 @@ export default {
   isIRI,
   isList,
   isLiteral,
+  isOptionalNode,
   isRequired,
   isBoolean,
   isInteger,