SchemaService - improve resolve ref. function and naming

* In the resolveRef function: check that the linking property's schema
has a type
* Added test case for this
* Renamed findTargetReferences to getFindReferenceTargetsFunction to
make clear that it returns a function

Author: lucas-koehler

src/core/schema.service.impl.ts

@@ -92,6 +92,9 @@ const resolveRef = (schema: JsonSchema, findTargets: (rootData: Object) => Objec
     // get all objects that could be referenced.
     const candidates = findTargets(rootData);
 
+    if (_.isEmpty(schema.properties[propName].type)) {
+      throw Error(`The schema of the property '${propName}' does not specify a schema type.`);
+    }
     if (schema.properties[propName].type === 'array') {
       const ids: object[] = data[propName];
       const resultList = candidates.filter(value => ids.indexOf(value[identifyingProperty]) > -1);
@@ -124,7 +127,7 @@ const resolveRef = (schema: JsonSchema, findTargets: (rootData: Object) => Objec
     }
   };
 
-const findReferenceTargets = (pathToContainment: string, schemaId: string) =>
+const getFindReferenceTargetsFunction = (pathToContainment: string, schemaId: string) =>
   (rootData: Object) => {
     const candidates = pathToContainment
       .split('/')
@@ -197,17 +200,17 @@ export class SchemaServiceImpl implements SchemaService {
         const variableWrapped = href.match(/\{.*\}/)[0];
         const pathToContainment = href.split(/\/\{.*\}/)[0];
         const variable = variableWrapped.substring(1, variableWrapped.length - 1);
-        const foundTargets = findReferenceTargets(pathToContainment, targetSchema.id);
+        const findTargets = getFindReferenceTargetsFunction(pathToContainment, targetSchema.id);
         const identifyingProp = JsonForms.config.getIdentifyingProp();
         result.push(
           new ReferencePropertyImpl(
             schema.properties[variable],
             targetSchema,
             variable,
             variable,
-            foundTargets,
+            findTargets,
             addReference(schema, identifyingProp, variable),
-            resolveRef(schema, foundTargets, identifyingProp, variable)
+            resolveRef(schema, findTargets, identifyingProp, variable)
           )
         );
       });

test/schema.service.test.ts

@@ -795,6 +795,43 @@ test('reference array properties get multiple', t => {
   t.is(getDataArray[0], data.classes[0]);
   t.is(getDataArray[1], data.classes[2]);
 });
+test(`reference properties get - linking property's schema without type`, t => {
+  const schema = {
+    definitions: {
+      class: {
+        type: 'object',
+        properties: {
+          id: {
+            type: 'string'
+          },
+          association: {
+            type: ''
+          }
+        },
+        links: [{
+          rel: 'full',
+          href: '#/classes/{association}',
+          targetSchema: {$ref: '#/definitions/class'}
+        }]
+      }
+    },
+    type: 'object',
+    properties: {
+      classes: {
+        type: 'array',
+        items: {
+          $ref: '#/definitions/class'
+        }
+      }
+    }
+  };
+
+  const service: SchemaService = new SchemaServiceImpl(schema);
+  const property = service.getReferenceProperties(schema.properties.classes.items as JsonSchema)[0];
+  const data = {classes: [{id: 'c1'}, {id: 'c2', association: 'c1'}]};
+  const error: Error = t.throws(() => property.getData(data, data.classes[1]));
+  t.is(error.message, `The schema of the property 'association' does not specify a schema type.`);
+});
 
 test('reference property find reference targets', t => {
   const schema = t.context.referenceFindSchema;