/*******************************************************************************
* Copyright (c) 1998, 2009 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.mappings.converters;
import java.util.*;
import org.eclipse.persistence.mappings.*;
import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.internal.descriptors.TypeMapping;
import org.eclipse.persistence.internal.helper.*;
import org.eclipse.persistence.mappings.foundation.AbstractDirectMapping;
import org.eclipse.persistence.sessions.*;
import org.eclipse.persistence.internal.sessions.AbstractSession;
/**
* <b>Purpose</b>: Object type converter is used to match a fixed number of database data values
* to Java object value. It can be used when the values on the database and in the Java differ.
* To create an object type converter, simply specify the set of conversion value pairs.
* A default value and one-way conversion are also supported for legacy data situations.
*
* @author James Sutherland
* @since Toplink 10
*/
public class ObjectTypeConverter implements Converter {
protected DatabaseMapping mapping;
protected transient Map fieldToAttributeValues;
protected Map attributeToFieldValues;
protected transient Object defaultAttributeValue;
protected transient Class fieldClassification;
protected transient String fieldClassificationName;
/**
* PUBLIC:
* Default constructor.
*/
public ObjectTypeConverter() {
this.attributeToFieldValues = new HashMap(10);
this.fieldToAttributeValues = new HashMap(10);
}
/**
* PUBLIC:
* Default constructor.
*/
public ObjectTypeConverter(DatabaseMapping mapping) {
this();
this.mapping = mapping;
}
/**
* PUBLIC:
* A type conversion value is a two-way mapping from the database to the object.
* The database value will be substituted for the object value when read,
* and the object value will be substituted for database value when written.
* Note that each field/attribute value must have one and only one attribute/field value to maintain a two-way mapping.
*/
public void addConversionValue(Object fieldValue, Object attributeValue) {
if (fieldValue == null) {
fieldValue = Helper.getNullWrapper();
}
if (attributeValue == null) {
attributeValue = Helper.getNullWrapper();
}
getFieldToAttributeValues().put(fieldValue, attributeValue);
getAttributeToFieldValues().put(attributeValue, fieldValue);
}
/**
* PUBLIC:
* An attribute only conversion value is a one-way mapping from the database to the object.
* This can be used if multiple database values are desired to be mapped to the same object value.
* Note that when written only the default value will be used for the attribute, not this value.
*/
public void addToAttributeOnlyConversionValue(Object fieldValue, Object attributeValue) {
if (fieldValue == null) {
fieldValue = Helper.getNullWrapper();
}
if (attributeValue == null) {
attributeValue = Helper.getNullWrapper();
}
getFieldToAttributeValues().put(fieldValue, attributeValue);
}
/**
* INTERNAL:
* Get the attribute to field mapping.
*/
public Map getAttributeToFieldValues() {
return attributeToFieldValues;
}
/**
* INTERNAL:
* Convert all the class-name-based settings in this converter to actual
* class-based settings. This method is used when converting a project
* that has been built with class names to a project with classes.
* @param classLoader
*/
public void convertClassNamesToClasses(ClassLoader classLoader){
// Does nothing right now but was implemented since EnumTypeConverter
// is dependent on this method but we need to avoid JDK 1.5
// dependencies. AbstractDirectMapping will call this method.
}
/**
* INTERNAL:
* Returns the corresponding attribute value for the specified field value.
*/
public Object convertDataValueToObjectValue(Object fieldValue, Session session) {
Object attributeValue = null;
if (fieldValue == null) {
attributeValue = getFieldToAttributeValues().get(Helper.getNullWrapper());
} else {
try {
fieldValue = ((AbstractSession)session).getDatasourcePlatform().getConversionManager().convertObject(fieldValue, getFieldClassification());
} catch (ConversionException e) {
throw ConversionException.couldNotBeConverted(mapping, mapping.getDescriptor(), e);
}
attributeValue = getFieldToAttributeValues().get(fieldValue);
if (attributeValue == null) {
if (getDefaultAttributeValue() != null) {
attributeValue = getDefaultAttributeValue();
} else {
// CR#3779
throw DescriptorException.noFieldValueConversionToAttributeValueProvided(fieldValue, getMapping().getField(), getMapping());
}
}
}
return attributeValue;
}
/**
* PUBLIC:
* The default value can be used if the database can possibly store additional values then those that
* have been mapped. Any value retreived from the database that is not mapped will be substitued for the default value.
*/
public Object getDefaultAttributeValue() {
return defaultAttributeValue;
}
/**
* INTERNAL:
* Return the mapping.
*/
protected DatabaseMapping getMapping() {
return mapping;
}
/**
* INTERNAL:
* Set the mapping.
*/
protected void setMapping(DatabaseMapping mapping) {
this.mapping = mapping;
}
/**
* INTERNAL:
* Get the type of the field value to allow conversion from the database.
*/
public Class getFieldClassification() {
return fieldClassification;
}
public String getFieldClassificationName() {
if ((fieldClassificationName == null) && (fieldClassification != null)) {
fieldClassificationName = fieldClassification.getName();
}
return fieldClassificationName;
}
/**
* INTERNAL:
* Return the classifiction for the field contained in the mapping.
* This is used to convert the row value to a consistent java value.
* By default this is null which means unknown.
*/
public Class getFieldClassification(DatabaseField fieldToClassify) {
return getFieldClassification();
}
/**
* INTERNAL:
* Return a collection of the field to attribute value associations.
*/
public Vector getFieldToAttributeValueAssociations() {
Vector associations = new Vector(getFieldToAttributeValues().size());
Iterator fieldValueEnum = getFieldToAttributeValues().keySet().iterator();
Iterator attributeValueEnum = getFieldToAttributeValues().values().iterator();
while (fieldValueEnum.hasNext()) {
Object fieldValue = fieldValueEnum.next();
if (fieldValue == Helper.getNullWrapper()) {
fieldValue = null;
}
Object attributeValue = attributeValueEnum.next();
if (attributeValue == Helper.getNullWrapper()) {
attributeValue = null;
}
associations.addElement(new TypeMapping(fieldValue, attributeValue));
}
return associations;
}
/**
* INTERNAL:
* Get the field to attribute mapping.
*/
public Map getFieldToAttributeValues() {
return fieldToAttributeValues;
}
/**
* INTERNAL:
* Convert to the data value.
*/
public Object convertObjectValueToDataValue(Object attributeValue, Session session) {
Object fieldValue;
if (attributeValue == null) {
fieldValue = getAttributeToFieldValues().get(Helper.getNullWrapper());
} else {
fieldValue = getAttributeToFieldValues().get(attributeValue);
if (fieldValue == null) {
throw DescriptorException.noAttributeValueConversionToFieldValueProvided(attributeValue, getMapping());
}
}
return fieldValue;
}
/**
* PUBLIC:
* This is a very specific protocol which maps fieldValues "T" and "F"
* to true and false respectively.
*/
public void mapBooleans() {
addConversionValue("F", new Boolean(false));
addConversionValue("T", new Boolean(true));
}
/**
* PUBLIC:
* This is a very specific protocol which maps fieldValues "F" and "M"
* to "Female" and "Male" respectively.
*/
public void mapGenders() {
addConversionValue("F", "Female");
addConversionValue("M", "Male");
}
/**
* PUBLIC:
* This is a very specific protocol which maps fieldValues "Y" and "N"
* to "Yes" and "No" respectively.
*/
public void mapResponses() {
addConversionValue("Y", "Yes");
addConversionValue("N", "No");
}
/**
* INTERNAL:
* Set the field classification through searching the fields hashtable.
*/
public void initializeFieldClassification(Session session) throws DescriptorException {
if (getFieldToAttributeValues().isEmpty()) {
return;
}
Class type = null;
Iterator fieldValuesEnum = getFieldToAttributeValues().keySet().iterator();
while (fieldValuesEnum.hasNext() && (type == null)) {
Object value = fieldValuesEnum.next();
if (value != Helper.getNullWrapper()) {
type = value.getClass();
}
}
setFieldClassification(type);
// CR#... Mapping must also have the field classification.
if (getMapping().isDirectToFieldMapping()) {
AbstractDirectMapping directMapping = (AbstractDirectMapping)getMapping();
// Allow user to specify field type to override computed value. (i.e. blob, nchar)
if (directMapping.getFieldClassification() == null) {
directMapping.setFieldClassification(type);
}
}
}
/**
* INTERNAL:
* Set the mapping.
*/
public void initialize(DatabaseMapping mapping, Session session) {
this.mapping = mapping;
initializeFieldClassification(session);
}
/**
* INTERNAL:
* Set the attribute to field mapping.
*/
public void setAttributeToFieldValues(Map attributeToFieldValues) {
this.attributeToFieldValues = attributeToFieldValues;
}
/**
* PUBLIC:
* The default value can be used if the database can possibly store additional values then those that
* have been mapped. Any value retreived from the database that is not mapped will be substitued for the default value.
*/
public void setDefaultAttributeValue(Object defaultAttributeValue) {
this.defaultAttributeValue = defaultAttributeValue;
}
/**
* INTERNAL:
* Set the type of the field value to allow conversion from the database.
*/
public void setFieldClassification(Class fieldClassification) {
this.fieldClassification = fieldClassification;
}
public void setFieldClassificationName(String fieldClassificationName) {
this.fieldClassificationName = fieldClassificationName;
}
/**
* INTERNAL:
* Set a collection of the field to attribute value associations.
*/
public void setFieldToAttributeValueAssociations(Vector fieldToAttributeValueAssociations) {
setFieldToAttributeValues(new HashMap(fieldToAttributeValueAssociations.size() + 1));
setAttributeToFieldValues(new HashMap(fieldToAttributeValueAssociations.size() + 1));
for (Enumeration associationsEnum = fieldToAttributeValueAssociations.elements();
associationsEnum.hasMoreElements();) {
Association association = (Association)associationsEnum.nextElement();
addConversionValue(association.getKey(), association.getValue());
}
}
/**
* INTERNAL:
* Set the field to attribute mapping.
*/
public void setFieldToAttributeValues(Map fieldToAttributeValues) {
this.fieldToAttributeValues = fieldToAttributeValues;
}
/**
* INTERNAL:
* If the converter converts the value to a non-atomic value, i.e.
* a value that can have its' parts changed without being replaced,
* then it must return false, serialization can be non-atomic.
*/
public boolean isMutable() {
return false;
}
}