Support primitive java types

datatype/src/main/java/cz/cvut/kbss/jopa/datatype/DatatypeTransformer.java

@@ -41,6 +41,16 @@ public class DatatypeTransformer {
 
     private static final Map<Pair, Function<Object, ?>> TRANSFORMERS = initTransformers();
 
+    private static final Map<Class<?>, Class<?>> WRAPPER_TO_PRIMITIVES = Map.of(
+            Integer.class, int.class,
+            Boolean.class, boolean.class,
+            Byte.class, byte.class,
+            Short.class, short.class,
+            Long.class, long.class,
+            Float.class, float.class,
+            Double.class, double.class
+    );
+
     private DatatypeTransformer() {
         throw new AssertionError();
     }
@@ -79,6 +89,22 @@ private DatatypeTransformer() {
         return map;
     }
 
+    /**
+     * Converts the specified wrapper class to its corresponding primitive class.
+     *
+     * If the class parameter is a wrapper type, the equivalent primitive type will be returned (e.g. int.class for Integer.class)
+     * In all other cases, the return value is null.
+     *
+     * @param cls - the class to convert
+     * @return
+     */
+    public static Optional<Class<?>> wrapperTypeToPrimitiveType(Class<?> cls) {
+        if(cls != null && WRAPPER_TO_PRIMITIVES.containsKey(cls)) {
+            return Optional.of(WRAPPER_TO_PRIMITIVES.get(cls));
+        }
+        return Optional.empty();
+    }
+
     /**
      * Maps the specified value to the target type (if possible).
      *

datatype/src/test/java/cz/cvut/kbss/jopa/datatype/DatatypeTransformerTest.java

@@ -26,12 +26,36 @@
 
 import java.net.InetAddress;
 import java.net.URL;
+import java.util.Optional;
 import java.util.stream.Stream;
 
 import static org.junit.jupiter.api.Assertions.*;
 
 class DatatypeTransformerTest {
 
+    @Test
+    void wrapperTypeToPrimitiveTypeReturnsNullForNullInput() {
+        assertEquals(Optional.empty(), DatatypeTransformer.wrapperTypeToPrimitiveType(null));
+    }
+
+    @ParameterizedTest
+    @MethodSource("wrapperTypeToPrimitiveTypeTestValues")
+    void wrapperTypeToPrimitiveType(Class<?> wrapper, Class<?> primitive) {
+        assertEquals(Optional.of(primitive), DatatypeTransformer.wrapperTypeToPrimitiveType(wrapper));
+    }
+
+    private static Stream<Arguments> wrapperTypeToPrimitiveTypeTestValues() {
+        return Stream.of(
+                Arguments.arguments(Integer.class, int.class),
+                Arguments.arguments(Boolean.class, boolean.class),
+                Arguments.arguments(Byte.class, byte.class),
+                Arguments.arguments(Short.class, short.class),
+                Arguments.arguments(Long.class, long.class),
+                Arguments.arguments(Float.class, float.class),
+                Arguments.arguments(Double.class, double.class)
+        );
+    }
+
     @Test
     void transformReturnsNullForNullInput() {
         assertNull(DatatypeTransformer.transform(null, String.class));

jopa-impl/src/main/java/cz/cvut/kbss/jopa/model/metamodel/ClassFieldMetamodelProcessor.java

@@ -82,9 +82,6 @@ void processField(Field field) {
             }
             return;
         }
-        if (field.getType().isPrimitive()) {
-            throw new MetamodelInitializationException("Primitive types cannot be used for entity fields. Field " + field + " in class " + cls);
-        }
 
         final Class<?> fieldValueCls = getFieldValueType(field);
         field.setAccessible(true);

jopa-impl/src/main/java/cz/cvut/kbss/jopa/model/metamodel/Converters.java

@@ -29,6 +29,7 @@
 import cz.cvut.kbss.jopa.oom.converter.ToStringConverter;
 import cz.cvut.kbss.jopa.oom.converter.ToURIConverter;
 import cz.cvut.kbss.jopa.oom.converter.ToURLConverter;
+import cz.cvut.kbss.jopa.oom.converter.CharacterConverter;
 import cz.cvut.kbss.jopa.oom.converter.datetime.DateConverter;
 import cz.cvut.kbss.jopa.oom.converter.datetime.InstantConverter;
 import cz.cvut.kbss.jopa.oom.converter.datetime.LocalDateTimeConverter;
@@ -91,7 +92,9 @@ void registerConverter(Class<?> attributeType, ConverterWrapper<?, ?> converter)
                 Map.entry(String.class, new ToStringConverter()),
                 Map.entry(LangString.class, new ToLangStringConverter()),
                 Map.entry(URI.class, new ToURIConverter()),
-                Map.entry(URL.class, new ToURLConverter()));
+                Map.entry(URL.class, new ToURLConverter()),
+                Map.entry(Character.class, new CharacterConverter()),
+                Map.entry(char.class, new CharacterConverter()));
     }
 
     /**

jopa-impl/src/main/java/cz/cvut/kbss/jopa/model/metamodel/PropertyAttributes.java

@@ -17,6 +17,7 @@
  */
 package cz.cvut.kbss.jopa.model.metamodel;
 
+import cz.cvut.kbss.jopa.datatype.DatatypeTransformer;
 import cz.cvut.kbss.jopa.model.IRI;
 import cz.cvut.kbss.jopa.model.MultilingualString;
 import cz.cvut.kbss.jopa.model.annotations.CascadeType;
@@ -133,7 +134,9 @@ private void resolveEnumType(PropertyInfo propertyInfo, Class<?> fieldValueCls)
     }
 
     String resolveLanguage(Class<?> fieldValueCls) {
-        return MultilingualString.class.equals(fieldValueCls) ? null : typeBuilderContext.getPuLanguage();
+        return MultilingualString.class.equals(fieldValueCls) || Character.class.equals(fieldValueCls) || char.class.equals(fieldValueCls)
+                ? null
+                : typeBuilderContext.getPuLanguage();
     }
 
     static PropertyAttributes create(PropertyInfo field, FieldMappingValidator validator, TypeBuilderContext<?> context) {

jopa-impl/src/main/java/cz/cvut/kbss/jopa/oom/DataPropertyFieldStrategy.java

@@ -17,6 +17,7 @@
  */
 package cz.cvut.kbss.jopa.oom;
 
+import cz.cvut.kbss.jopa.datatype.DatatypeTransformer;
 import cz.cvut.kbss.jopa.model.descriptors.Descriptor;
 import cz.cvut.kbss.jopa.model.metamodel.AbstractAttribute;
 import cz.cvut.kbss.jopa.model.metamodel.EntityType;
@@ -27,6 +28,7 @@
 
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Optional;
 
 abstract class DataPropertyFieldStrategy<A extends AbstractAttribute<? super X, ?>, X> extends FieldStrategy<A, X> {
 
@@ -43,6 +45,14 @@ boolean isValidRange(Object value) {
     }
 
     boolean canBeConverted(Object value) {
+        if(attribute.getJavaType().isPrimitive()) {
+            // if the value is a wrapper for the primitive attribute type, it can be converted automatically
+            Optional<Class<?>> primitiveClass = DatatypeTransformer.wrapperTypeToPrimitiveType(value.getClass());
+            if (primitiveClass.isPresent() && primitiveClass.get().equals(attribute.getJavaType())) {
+                return true;
+            }
+        }
+
         return converter.supportsAxiomValueType(value.getClass());
     }
 

jopa-impl/src/main/java/cz/cvut/kbss/jopa/oom/converter/CharacterConverter.java

@@ -0,0 +1,51 @@
+/*
+ * JOPA
+ * Copyright (C) 2024 Czech Technical University in Prague
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3.0 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.
+ */
+package cz.cvut.kbss.jopa.oom.converter;
+
+import cz.cvut.kbss.jopa.datatype.exception.DatatypeMappingException;
+import cz.cvut.kbss.ontodriver.model.LangString;
+
+/**
+ * Converts between {@link Character} and a xsd:string representation.
+ * <p>
+ * This converter supports {@link String} and {@link LangString} as character representations.
+ */
+public class CharacterConverter implements ConverterWrapper<Character, Object> {
+
+    @Override
+    public Object convertToAxiomValue(Character value) {
+        assert value != null;
+        return value.toString();
+    }
+
+    @Override
+    public Character convertToAttribute(Object value) {
+        assert value != null && value instanceof String;
+
+        if(((String) value).length() > 1) {
+            throw new DatatypeMappingException("Unable to map literal " + value + " to " + Character.class.getCanonicalName() + ", because its length is greater than 1");
+        }
+
+        return ((String) value).charAt(0);
+    }
+
+    @Override
+    public boolean supportsAxiomValueType(Class<?> type) {
+        return String.class.isAssignableFrom(type);
+    }
+}

jopa-impl/src/test/java/cz/cvut/kbss/jopa/environment/OWLClassM.java

@@ -54,6 +54,9 @@ public class OWLClassM {
     @OWLDataProperty(iri = Vocabulary.p_m_dateAttribute)
     private Date dateAttribute;
 
+    @OWLDataProperty(iri = Vocabulary.p_m_characterAttribute)
+    private Character characterAttribute;
+
     @OWLDataProperty(iri = Vocabulary.p_m_enumAttribute)
     private Severity enumAttribute;
 
@@ -133,6 +136,14 @@ public void setDateAttribute(Date dateAttribute) {
         this.dateAttribute = dateAttribute;
     }
 
+    public Character getCharacterAttribute() {
+        return characterAttribute;
+    }
+
+    public void setCharacterAttribute(Character characterAttribute) {
+        this.characterAttribute = characterAttribute;
+    }
+
     public Severity getEnumAttribute() {
         return enumAttribute;
     }
@@ -191,12 +202,14 @@ public void setObjectOneOfEnumAttribute(OneOfEnum objectOneOfEnumAttribute) {
 
     @Override
     public String toString() {
-        return "OWLCLassM{" +
+        return "OWLClassM{" +
                 "key='" + key + '\'' +
                 ", booleanAttribute=" + booleanAttribute +
                 ", intAttribute=" + intAttribute +
                 ", longAttribute=" + longAttribute +
                 ", doubleAttribute=" + doubleAttribute +
+                ", dateAttribute=" + dateAttribute +
+                ", characterAttribute=" + characterAttribute +
                 ", enumAttribute=" + enumAttribute +
                 ", ordinalEnumAttribute=" + ordinalEnumAttribute +
                 ", integerSet=" + integerSet +
@@ -217,6 +230,7 @@ public void initializeTestValues(boolean includingKey) {
         this.longAttribute = 365L;
         this.doubleAttribute = 3.14D;
         this.dateAttribute = new Date();
+        this.characterAttribute = 'j';
         this.enumAttribute = Severity.MEDIUM;
         this.ordinalEnumAttribute = enumAttribute;
         this.integerSet = IntStream.generate(Generators::randomInt).limit(10).boxed().collect(Collectors.toSet());
@@ -263,6 +277,14 @@ public static PropertyInfo getDateAttributeFieldPropertyInfo() throws Exception
         return PropertyInfo.from(OWLClassM.getDateAttributeField());
     }
 
+    public static Field getCharacterAttributeField() throws Exception {
+        return OWLClassM.class.getDeclaredField("characterAttribute");
+    }
+
+    public static PropertyInfo getCharacterAttributeFieldPropertyInfo() throws Exception {
+        return PropertyInfo.from(OWLClassM.getCharacterAttributeField());
+    }
+
     public static Field getEnumAttributeField() throws Exception {
         return OWLClassM.class.getDeclaredField("enumAttribute");
     }

jopa-impl/src/test/java/cz/cvut/kbss/jopa/environment/Vocabulary.java

@@ -61,6 +61,7 @@ public class Vocabulary {
     public static final String p_m_longAttribute = ATTRIBUTE_BASE + "m-longAttribute";
     public static final String p_m_doubleAttribute = ATTRIBUTE_BASE + "m-doubleAttribute";
     public static final String p_m_dateAttribute = ATTRIBUTE_BASE + "m-dateAttribute";
+    public static final String p_m_characterAttribute = ATTRIBUTE_BASE + "m-characterAttribute";
     public static final String p_m_enumAttribute = ATTRIBUTE_BASE + "m-enumAttribute";
     public static final String p_m_ordinalEnumAttribute = ATTRIBUTE_BASE + "m-ordinalEnumAttribute";
     public static final String p_m_IntegerSet = ATTRIBUTE_BASE + "m-pluralIntAttribute";

jopa-impl/src/test/java/cz/cvut/kbss/jopa/environment/utils/MetamodelFactory.java

@@ -95,6 +95,7 @@
 import cz.cvut.kbss.jopa.oom.converter.ToIntegerConverter;
 import cz.cvut.kbss.jopa.oom.converter.ToLexicalFormConverter;
 import cz.cvut.kbss.jopa.oom.converter.ToLongConverter;
+import cz.cvut.kbss.jopa.oom.converter.CharacterConverter;
 import cz.cvut.kbss.jopa.oom.converter.datetime.LocalDateTimeConverter;
 import cz.cvut.kbss.jopa.utils.Configuration;
 import cz.cvut.kbss.jopa.vocabulary.DC;
@@ -735,7 +736,7 @@ public static void initOWLClassLMocks(IdentifiableEntityType<OWLClassL> etMock,
 
     public static void initOWLClassMMock(IdentifiableEntityType<OWLClassM> etMock, AbstractAttribute booleanAtt,
                                          AbstractAttribute intAtt, SingularAttributeImpl longAtt,
-                                         AbstractAttribute doubleAtt, AbstractAttribute dateAtt,
+                                         AbstractAttribute doubleAtt, AbstractAttribute dateAtt, AbstractAttribute characterAtt,
                                          AbstractAttribute enumAtt, AbstractAttribute ordinalEnumAtt,
                                          AbstractPluralAttribute intSetAtt, SingularAttributeImpl lexicalFormAtt,
                                          SingularAttributeImpl simpleLiteralAtt,
@@ -755,13 +756,13 @@ public static void initOWLClassMMock(IdentifiableEntityType<OWLClassM> etMock, A
         when(etMock.getFieldSpecification(idMock.getName())).thenReturn(idMock);
         when(etMock.getAttributes()).thenReturn(
                 new HashSet<>(Arrays.<Attribute<? super OWLClassM, ?>>asList(booleanAtt, intAtt, longAtt, doubleAtt,
-                        dateAtt, enumAtt, ordinalEnumAtt,
+                        dateAtt, characterAtt, enumAtt, ordinalEnumAtt,
                         intSetAtt, lexicalFormAtt,
                         simpleLiteralAtt, explicitDatatypeAtt,
                         mObjectOneOfEnumAttribute)));
         when(etMock.getFieldSpecifications()).thenReturn(new HashSet<>(
                 Arrays.<FieldSpecification<? super OWLClassM, ?>>asList(booleanAtt, intAtt, longAtt, doubleAtt, dateAtt,
-                        enumAtt, ordinalEnumAtt, intSetAtt,
+                        characterAtt, enumAtt, ordinalEnumAtt, intSetAtt,
                         lexicalFormAtt, simpleLiteralAtt,
                         explicitDatatypeAtt, mObjectOneOfEnumAttribute,
                         idMock)));
@@ -836,6 +837,20 @@ public static void initOWLClassMMock(IdentifiableEntityType<OWLClassM> etMock, A
         when(etMock.getFieldSpecification(OWLClassM.getDateAttributeField().getName())).thenReturn(dateAtt);
         when(etMock.getAttribute(OWLClassM.getDateAttributeField().getName())).thenReturn(dateAtt);
 
+        when(characterAtt.getJavaField()).thenReturn(OWLClassM.getCharacterAttributeField());
+        when(characterAtt.getName()).thenReturn(OWLClassM.getCharacterAttributeField().getName());
+        when(characterAtt.getJavaType()).thenReturn(OWLClassM.getCharacterAttributeField().getType());
+        when(characterAtt.getIRI()).thenReturn(IRI.create(Vocabulary.p_m_characterAttribute));
+        when(characterAtt.getPersistentAttributeType()).thenReturn(Attribute.PersistentAttributeType.DATA);
+        when(characterAtt.isCollection()).thenReturn(false);
+        when(characterAtt.getDeclaringType()).thenReturn(etMock);
+        when(characterAtt.getConstraints()).thenReturn(new ParticipationConstraint[0]);
+        when(characterAtt.getConverter()).thenReturn(new CharacterConverter());
+        when(characterAtt.hasLanguage()).thenReturn(true);
+        when(characterAtt.getLanguage()).thenReturn(Generators.LANG);
+        when(etMock.getFieldSpecification(OWLClassM.getCharacterAttributeField().getName())).thenReturn(characterAtt);
+        when(etMock.getAttribute(OWLClassM.getCharacterAttributeField().getName())).thenReturn(characterAtt);
+
         when(enumAtt.getJavaField()).thenReturn(OWLClassM.getEnumAttributeField());
         when(enumAtt.getName()).thenReturn(OWLClassM.getEnumAttributeField().getName());
         when(enumAtt.getJavaType()).thenReturn(OWLClassM.getEnumAttributeField().getType());

jopa-impl/src/test/java/cz/cvut/kbss/jopa/environment/utils/MetamodelMocks.java

@@ -206,6 +206,8 @@ public class MetamodelMocks {
     @Mock
     private SingularAttributeImpl<OWLClassM, Date> mDateAtt;
     @Mock
+    private SingularAttributeImpl<OWLClassM, Character> mCharacterAtt;
+    @Mock
     private SingularAttributeImpl<OWLClassM, OWLClassM.Severity> mEnumAtt;
     @Mock
     private SingularAttributeImpl<OWLClassM, OWLClassM.Severity> mOrdinalEnumAtt;
@@ -388,7 +390,7 @@ public MetamodelMocks() throws Exception {
         MetamodelFactory.initOWLClassJMocks(etJ, jSetAtt, idJ);
         MetamodelFactory.initOWLClassKMocks(etK, kOwlClassEAtt, idK);
         MetamodelFactory.initOWLClassLMocks(etL, lReferencedList, lSimpleList, lSetAtt, lOwlClassAAtt, idL);
-        MetamodelFactory.initOWLClassMMock(etM, mBooleanAtt, mIntegerAtt, mLongAtt, mDoubleAtt, mDateAtt, mEnumAtt,
+        MetamodelFactory.initOWLClassMMock(etM, mBooleanAtt, mIntegerAtt, mLongAtt, mDoubleAtt, mDateAtt, mCharacterAtt, mEnumAtt,
                                            mOrdinalEnumAtt, mIntegerSetAtt, mLexicalFormAtt, mSimpleLiteralAtt,
                                            mExplicitDatatypeAtt, mWithConverterAtt, mObjectOneOfEnumAttribute, idM);
         MetamodelFactory.initOWLClassNMock(etN, nAnnotationAtt, nAnnotationUriAtt, nStringAtt, nPluralAnnotationAtt,
@@ -786,6 +788,10 @@ public AbstractAttribute<OWLClassM, Date> dateAttribute() {
             return MetamodelMocks.this.mDateAtt;
         }
 
+        public AbstractAttribute<OWLClassM, Character> characterAttribute() {
+            return MetamodelMocks.this.mCharacterAtt;
+        }
+
         public AbstractAttribute<OWLClassM, OWLClassM.Severity> enumAttribute() {
             return MetamodelMocks.this.mEnumAtt;
         }

jopa-impl/src/test/java/cz/cvut/kbss/jopa/model/MetamodelImplTest.java

@@ -181,6 +181,12 @@ void buildsSingleEntityWithMultipleSingularDataProperties() throws Exception {
                                FetchType.EAGER, false, dateField.getAnnotation(OWLDataProperty.class).iri(),
                                dateField.getType(),
                                new CascadeType[]{});
+        final Field characterField = OWLClassM.getCharacterAttributeField();
+        final FieldSpecification<? super OWLClassM, ?> characterAtt = et.getFieldSpecification(characterField.getName());
+        checkSingularAttribute(characterAtt, et, characterField.getName(), Attribute.PersistentAttributeType.DATA, characterField,
+                FetchType.EAGER, false, characterField.getAnnotation(OWLDataProperty.class).iri(),
+                characterField.getType(),
+                new CascadeType[]{});
         final Field enumField = OWLClassM.getEnumAttributeField();
         final FieldSpecification<? super OWLClassM, ?> enumAtt = et.getFieldSpecification(enumField.getName());
         checkSingularAttribute(enumAtt, et, enumField.getName(), Attribute.PersistentAttributeType.DATA, enumField,