#216 Json and schema are inconsistent when using an EMap reference (#227)

Generate schema for Map object.

closes #216

Author: Vincent HEMERY

bundles/org.eclipse.emfcloud.modelserver.common/src/org/eclipse/emfcloud/modelserver/jsonschema/DefaultJsonSchemaConverter.java

@@ -1,5 +1,5 @@
 /********************************************************************************
- * Copyright (c) 2019 EclipseSource and others.
+ * Copyright (c) 2019-2022 EclipseSource and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
@@ -10,8 +10,10 @@
  ********************************************************************************/
 package org.eclipse.emfcloud.modelserver.jsonschema;
 
+import java.text.MessageFormat;
 import java.util.Collection;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
@@ -126,20 +128,46 @@ protected JsonNode createJsonSchemaFromEStructuralFeature(final EStructuralFeatu
    }
 
    protected JsonNode createJsonSchema(final EReference eReference, final boolean featureAsAttribute) {
+      EClass eReferenceType = eReference.getEReferenceType();
       final ObjectNode objectNode = Json.object();
-      if (eReference.getUpperBound() > 1 || eReference.getUpperBound() == -1) {
-         objectNode.set("type", Json.text("array"));
-         JsonNode feature = Json.object();
-         if (!featureAsAttribute) {
-            feature = createJsonSchemaFromEClass(eReference.getEReferenceType());
+      if (eReference.isMany()) {
+         if (Map.Entry.class.equals(eReferenceType.getInstanceClass()) && eReference.isContainment()) {
+            // eReference points to a Map$Entry EClass and should be translated as a Map Object
+            EStructuralFeature keyFeature = eReferenceType.getEStructuralFeature("key");
+            if (!Optional.ofNullable(keyFeature).filter(EAttribute.class::isInstance).filter(f -> !f.isMany())
+               .isPresent()) {
+               // there is no key attribute in the Map$Entry EClass. The metamodel is incorrect and cannot be supported.
+               String msg = MessageFormat.format(
+                  "The EClass {0} has instance type name 'java.util.Map$Entry', but no 'key' monovalued attribute. It is incorrect, and schema cannot be generated for referencing property {1}::{2}.",
+                  eReferenceType.getName(), eReference.getEContainingClass().getName(), eReference.getName());
+               throw new IllegalArgumentException(msg);
+            }
+            EStructuralFeature valueFeature = eReferenceType.getEStructuralFeature("value");
+            if (!Optional.ofNullable(valueFeature).filter(f -> !f.isMany()).isPresent()) {
+               // there is no value feature in the Map$Entry EClass. The metamodel is incorrect and cannot be supported.
+               String msg = MessageFormat.format(
+                  "The EClass {0} has instance type name 'java.util.Map$Entry', but no 'value' monovalued property. It is incorrect, and schema cannot be generated for referencing property {1}::{2}.",
+                  eReferenceType.getName(), eReference.getEContainingClass().getName(), eReference.getName());
+               throw new IllegalArgumentException(msg);
+            }
+            objectNode.set("type", Json.text("object"));
+            JsonNode valueType = createJsonSchemaFromEStructuralFeature(valueFeature);
+            objectNode.set("additionalProperties", valueType);
          } else {
-            feature = Json.object().set("$ref",
-               TextNode.valueOf("#/definitions/" + eReference.getEType().getName().trim().toLowerCase()));
+            // eReference is multivalued and should be translated as an array
+            objectNode.set("type", Json.text("array"));
+            JsonNode feature = Json.object();
+            if (!featureAsAttribute) {
+               feature = createJsonSchemaFromEClass(eReferenceType);
+            } else {
+               feature = Json.object().set("$ref",
+                  TextNode.valueOf("#/definitions/" + eReference.getEType().getName().trim().toLowerCase()));
+            }
+            objectNode.set("items", feature);
          }
-         objectNode.set("items", feature);
          return objectNode;
       }
-      return createJsonSchema(eReference.getEReferenceType(), true);
+      return createJsonSchema(eReferenceType, true);
    }
 
    protected ObjectNode createJsonSchema(final EAttribute eAttribute) {

tests/org.eclipse.emfcloud.modelserver.common.tests/src/org/eclipse/emfcloud/modelserver/common/tests/jsonschema/DefaultJsonSchemaConverterEClassTest.java

@@ -1,5 +1,5 @@
 /********************************************************************************
- * Copyright (c) 2019 EclipseSource and others.
+ * Copyright (c) 2019-2022 EclipseSource and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
@@ -14,6 +14,7 @@
 import static org.junit.Assert.assertEquals;
 
 import java.util.Collections;
+import java.util.Map;
 
 import org.eclipse.emf.ecore.EAttribute;
 import org.eclipse.emf.ecore.EClass;
@@ -37,11 +38,14 @@ public class DefaultJsonSchemaConverterEClassTest extends DefaultJsonSchemaConve
 
    private static final String ECLASS_NAME = "TestEClass";
    private static final String REFECLASS_NAME = "TestEClass2";
+   private static final String MAPENTRYECLASS_NAME = "StringToStringMapEntry";
    private static final String REFERENCE_NAME = "testReference";
    private static final String ATTRIBUTE_NAME = "testAttribute";
 
    private EClass eClass;
    private EClass refClass;
+   /** An EClass used for correspondence with EMap entries. */
+   private EClass mapEntryClass;
    private EReference eReference;
    private EReference eReference2;
 
@@ -56,6 +60,12 @@ public void before() {
 
       refClass = EcoreFactory.eINSTANCE.createEClass();
       refClass.setName(REFECLASS_NAME);
+
+      mapEntryClass = EcoreFactory.eINSTANCE.createEClass();
+      mapEntryClass.setName(MAPENTRYECLASS_NAME);
+      mapEntryClass.setInstanceClass(Map.Entry.class);
+      mapEntryClass.getEAttributes().add(EcoreTestUtil.stringEAttribute("key", 0, 1));
+      mapEntryClass.getEAttributes().add(EcoreTestUtil.stringEAttribute("value", 0, 1));
    }
 
    @Test
@@ -220,4 +230,24 @@ public void createJsonSchemaFromEClassWithMandatoryStringAttribute() throws Json
       assertEquals(expected, actual);
    }
 
+   @Test
+   public void createJsonSchemaFromEClassWithEMapReference() {
+      eReference = EcoreTestUtil.eReference(REFERENCE_NAME, 0, -1, mapEntryClass);
+      eReference.setContainment(true);
+      eClass.getEStructuralFeatures().add(eReference);
+
+      final JsonNode actual = jsonSchemaCreator.from(eClass);
+      final ObjectNode expected = Json.object(
+         prop("$id", Json.text(getIdHelper(eClass))),
+         prop("title", Json.text(ECLASS_NAME)),
+         prop("type", Json.text("object")),
+         prop("properties", Json.object(
+            prop(REFERENCE_NAME, Json.object(
+               prop("type", Json.text("object")),
+               prop("additionalProperties", Json.object(prop("type", Json.text("string")))))))),
+         prop("additionalProperties", Json.bool(false)));
+
+      assertEquals(expected, actual);
+   }
+
 }