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How to configurate mapstruct to ignore map object when all field are null

env:
jdk: 17.0.1
mapstruct: 1.5.1.Final
Using the default configuration I generated the following code
protected AgentInfo wealthProdAccountInfoDTOToAgentInfo(WealthProdAccountInfoDTO wealthProdAccountInfoDTO) {
if ( wealthProdAccountInfoDTO == null ) {
return null;
}
String agentName = null;
String agentIdentityType = null;
String agentIdentityNo = null;
String agentIdentityExpireAt = null;
agentName = wealthProdAccountInfoDTO.getAgentName();
agentIdentityType = wealthProdAccountInfoDTO.getAgentIdentityType();
agentIdentityNo = wealthProdAccountInfoDTO.getAgentIdentityNo();
agentIdentityExpireAt = wealthProdAccountInfoDTO.getAgentIdentityExpireAt();
AgentInfo agentInfo = new AgentInfo( agentName, agentIdentityType, agentIdentityNo, agentIdentityExpireAt );
return agentInfo;
}
But I want to return null when all field of source are null, like this
protected AgentInfo wealthProdAccountInfoDTOToAgentInfo(WealthProdAccountInfoDTO wealthProdAccountInfoDTO) {
if ( wealthProdAccountInfoDTO == null ) {
return null;
}
// add check logic
if (agentName == null && agentIdentityType == null && agentIdentityNo == null && agentIdentityExpireAt == null) {
return null;
}
String agentName = null;
String agentIdentityType = null;
String agentIdentityNo = null;
String agentIdentityExpireAt = null;
agentName = wealthProdAccountInfoDTO.getAgentName();
agentIdentityType = wealthProdAccountInfoDTO.getAgentIdentityType();
agentIdentityNo = wealthProdAccountInfoDTO.getAgentIdentityNo();
agentIdentityExpireAt = wealthProdAccountInfoDTO.getAgentIdentityExpireAt();
AgentInfo agentInfo = new AgentInfo( agentName, agentIdentityType, agentIdentityNo, agentIdentityExpireAt );
return agentInfo;
}
how should I configure it?

Unfortunately there's no clean solution for your problem, except implementing code for null check by yourself, Marc specified the right approach to your problem (I'd go with it personally or would use default method for the same purpose).
I can add some workarounds, which will only work if mapping target is inner object:
Use #BeforeMapping to set input inner object to null, so when there will be null-check it will be skipped
#BeforeMapping
default void clearData(TestB source, #MappingTarget TestA target) {
TestD innerD = source.getInnerD();
if (innerD.getSecond() == null && innerD.getFirst() == null) {
source.setInnerD(null);
}
}
And it will generate the following code:
#Override
public TestA from(TestB input) {
....
clearData( input, testA ); //set input field to null
testA.setInnerC( fromInner( input.getInnerD() ) );
....
}
#Override
public TestC fromInner(TestD input) {
if ( input == null ) { //skip because of null
return null;
}
....
}
Use #AfterMapper to set output parameter to null(it will be mapped in the first place, so there will be some overhead)
#AfterMapping
default void clearData(TestB source, #MappingTarget TestA target) {
TestD innerD = source.getInnerD();
if (innerD.getSecond() == null && innerD.getFirst() == null) {
target.setInnerC(null);
}
}
And generated code will be:
#Override
public TestA from(TestB input) {
....
testA.setInnerC( fromInner( input.getInnerD() ) ); //field is actually mapped but cleared later
clearData( input, testA );
return testA;
}
As I said, these solutions aren't really clean and should be seen as workarounds only. Pros of these workaround is that you will keep working with autogenerated code and these hacks will be hidden inside that code.
UPD Stumbled upon #DecoratedWith lately and it also can do the trick. https://mapstruct.org/documentation/stable/reference/html/#_customizing_mappings
Just implement decorator for iterable2iterable mapping method: List<A> from(List<b> b) and just manually iterate over b checking if all b's fields are null and if so skip it

brute force... it's a simple class, so create a custom mapper
#Mapper
public interface AgentInfoMapper {
#Named("AgentInfoNullIfContentsNull")
public static AgentInfo custom(WealthProdAccountInfoDTO dto) {
if ( wealthProdAccountInfoDTO == null ) {
return null;
}
if (agentName == null && agentIdentityType == null && agentIdentityNo == null && agentIdentityExpireAt == null) {
return null;
}
// mapping code
}
}
https://www.baeldung.com/mapstruct-custom-mapper

Thanks to ArtemAgaev's idea, I ended up considering using #AfterMapping and java reflection for this type of scenario
#AfterMapping
default void cleanData(#MappingTarget AccountInfoDomain domain) {
Optional.ofNullable(domain).ifPresent(c -> {
if (isAllFieldNull(domain.getAgentInfo())) {
domain.setAgentInfo(null);
}
});
}
public static boolean isAllFieldNull(Object o) {
Object[] fieldsValue = getFieldsValue(o);
return Optional.ofNullable(fieldsValue).map(f -> Arrays.stream(f).allMatch(Objects::isNull)).orElse(true);
}
public static Object[] getFieldsValue(Object obj) {
if (null != obj) {
final Field[] fields = getFields(obj instanceof Class ? (Class<?>) obj : obj.getClass());
if (null != fields) {
final Object[] values = new Object[fields.length];
for (int i = 0; i < fields.length; i++) {
values[i] = getFieldValue(obj, fields[i]);
}
return values;
}
}
return null;
}

Getting the type of method parameters in reflection

I work with reflection. And I need to get the parameter method of my set () entity to call the corresponding fill method in accordance with the type.
try{
Class clazz = aClass.getClass();
Object object = clazz.newInstance();
while (clazz != Object.class){
Method[] methods = clazz.getDeclaredMethods();
for (Method method : methods){
if (method.isAnnotationPresent(ProductAnnotation.class)) {
Object[] strategyObj = new Object[1];
if (method.getReturnType().getName().equals("int")) { //reflexion never comes in if
strategyObj[0] = strategy.setInt(bundle.getString(method.getName().substring(3).toLowerCase()));
method.invoke(object, strategyObj);
}if (method.getParameterTypes().getClass().getTypeName().equals("String")){ //reflexion never comes in if
strategyObj[0] = strategy.setString(bundle.getString(method.getName().substring(3).toLowerCase()));
method.invoke(object, strategyObj);
}
}
}
clazz = clazz.getSuperclass();
}
return (FlyingMachine) object;
} catch (IllegalAccessException | IOException | InvocationTargetException | InstantiationException e) {
e.printStackTrace();
}
return null;
}
I tried to use getReturnedType () and getParametrTypes (), but the reflexion does not enter any condition. What was I wrong about?
My Annotation
#Retention(RetentionPolicy.RUNTIME)
#Target(value = ElementType.METHOD)
public #interface ProductAnnotation {
String value();
}
Methods that should cause reflection.Depending on the type of method, call one of these methods for further processing and filling in the data.
#Override
public int setInt(String title) throws IOException {
String line = null;
checkValue = true;
while (checkValue) {
System.out.println(title + "-->");
line = reader.readLine();
if (line.matches("\\d*")) {
System.out.println(title + " = " + Integer.parseInt(line));
checkValue = false;
} else {
System.out.println("Wrong value, try again");
checkValue = true;
}
}
return Integer.parseInt(line);
}
setString() works exactly the same scheme.

Method::getParameterTypes returns Class[].
So your code method.getParameterTypes().getClass() will always return [Ljava.lang.Class. try this code:
Class[] types = method.getParameterTypes();
if (types.length == 1 && types[0] == String.class) {
// your second condition...
}

Method with generic element List and access to field by reflection

I have a compound problem. I want to write a method that receives 3 arguments:
A string to compare
A List of generic element type
A field name (of List element) to compare its value to the first argument
This is what I have so far, but it is incomplete, since I don't know how to define the second argument and I don't know how to get the List elements class to define a single element (see the "?????" in the code below)
public class Object1 {
String name;
...
}
public class Object2 {
String address;
...
}
public class MyClass {
...
private List<Object1> list1 = new ArrayList<Object1>();
private List<Object2> list2 = new ArrayList<Object2>();
...
private boolean isUnique(String s, List<?> list, String field) {
boolean result = true;
?????? element = null;
Field f = null;
Class<?> c = ?????.class;
try {
f = c.getDeclaredField(field);
f.setAccessible(true);
} catch( NoSuchFieldException e ) {
e.printStackTrace();
}
int size = list.size();
for( int i = 0; i < size; i++ ) {
element = list.get(i);
try {
if( s.equals(f.get(element))) {
result = false;
break;
}
} catch( IllegalArgumentException e ) {
e.printStackTrace();
} catch( IllegalAccessException e ) {
e.printStackTrace();
}
}
return result;
}
public boolean check(){
boolean result = isUnique("Stewart", list1, "name");
result = result & isUnique("21 pine", list2, "address");
return result;
}
}

Object element = null;
Field f = null;
if(list.size()>0)
{
Class<?> c = list.get(0).getClass();
try {
f = c.getDeclaredField(field);
f.setAccessible(true);
} catch( NoSuchFieldException e ) {
e.printStackTrace();
}
int size = list.size();
for( int i = 0; i < size; i++ ) {
element = list.get(i);
try {
if( s.equals(f.get(element))) {
result = false;
break;
}
} catch( IllegalArgumentException e ) {
e.printStackTrace();
} catch( IllegalAccessException e ) {
e.printStackTrace();
}
}
return result;
}else
{
return true;
}

Java Hibernate Transformer AliasToBeanNestedResultTransformer

i have a query like this. i pass the student ID i need some fields from Student as well as their parent as well some fields from the parent->Address[here is the main problem i am facing] i am using AliasToBeanNestedResultTransformer transformer by Sami Andoni
here is the implementation of it CODE
here is my code.
public List<Student>searchForStudent(Integer studentId)
{
Projection p=Projections.projectionList().create()
.add(Projections.property("name"),"name")//the student name it works O.K
.add(Projections.property("lastname"),"lastname")//the student name it works O.K
.add(Projections.property("age"),"age")//the student AGE it works O.K
.add(Projections.property("p.phone"),"parent.phone")//the parent phone it works O.K
.add(Projections.property("address.state").as("parent.Address.state")); // i need a field from address.state here is the problem...
Session session = ......
Criteria like = session.createCriteria(Student.class).add(prepareForSelect())//some filters..
.createAlias("parent","p")//the parent of the student. a student have one parent
.createAlias("parent.Address","address")//the address of the parent.... a parent have one address.
.setProjection(p)
.setResultTransformer(new AliasToBeanNestedResultTransformer(Student.class));
List<Student>results=like.list();
return results;
}
it throws
Exception in thread "main" org.hibernate.PropertyAccessException: IllegalArgumentException occurred while calling setter of com.generic.model.Parent.Address
FYI is some type mismatch i have done some tracing in SAMI code and i see this
[MyState]
[Address]
seems that Hibernate is returning a String State MyState in this case and the transformer is using a Address Object and this is the type Mismatch.
is any help is hugely needed it
thanks a lot.

I have improved the SamiAndoni class, maybe it solve your issue
package com.alutiiq.develop.promanagesys.core.util;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.hibernate.HibernateException;
import org.hibernate.property.PropertyAccessor;
import org.hibernate.property.PropertyAccessorFactory;
import org.hibernate.property.Setter;
import org.hibernate.transform.AliasToBeanResultTransformer;
import org.hibernate.transform.AliasedTupleSubsetResultTransformer;
import org.hibernate.transform.ResultTransformer;
/**
* Help to transform alises with nested alises
*
* #author Miguel Resendiz
*
*/
public class AliasToBeanNestedResultTransformer extends
AliasedTupleSubsetResultTransformer {
private static final long serialVersionUID = -8047276133980128266L;
private static final int TUPE_INDEX = 0;
private static final int ALISES_INDEX = 1;
private static final int FIELDNAME_INDEX = 2;
private static final PropertyAccessor accessor = PropertyAccessorFactory
.getPropertyAccessor("property");
private final Class<?> resultClass;
private Object[] entityTuples;
private String[] entityAliases;
private Map<String, Class<?>> fieldToClass = new HashMap<String, Class<?>>();
private Map<String, List<?>> subEntities = new HashMap<String, List<?>>();
private List<String> nestedAliases = new ArrayList<String>();
private Map<String, Class<?>> listFields = new HashMap<String, Class<?>>();
public boolean isTransformedValueATupleElement(String[] aliases,
int tupleLength) {
return false;
}
public AliasToBeanNestedResultTransformer(Class<?> resultClass) {
this.resultClass = resultClass;
}
public Object transformTuple(Object[] tuple, String[] aliases) {
handleSubEntities(tuple, aliases);
cleanParams(tuple, aliases);
ResultTransformer rootTransformer = new AliasToBeanResultTransformer(
resultClass);
Object root = rootTransformer.transformTuple(entityTuples,
entityAliases);
loadSubEntities(root);
cleanMaps();
return root;
}
private void handleSubEntities(Object[] tuple, String[] aliases)
throws HibernateException {
String fieldName = "";
String aliasName = "";
try {
for (int i = 0; i < aliases.length; i++) {
String alias = aliases[i];
if (alias.contains(".")) {
String[] sp = alias.split("\\.");
StringBuilder aliasBuilder = new StringBuilder();
for (int j = 0; j < sp.length; j++) {
if (j == 0) {
fieldName = sp[j];
} else {
aliasBuilder.append(sp[j]);
aliasBuilder.append(".");
}
}
aliasName = aliasBuilder.substring(0,
aliasBuilder.length() - 1);
nestedAliases.add(alias);
manageEntities(fieldName, aliasName, tuple[i]);
}
}
} catch (NoSuchFieldException e) {
throw new HibernateException("Could not instantiate resultclass: "
+ resultClass.getName() + " for field name: " + fieldName
+ " and alias name:" + aliasName);
}
}
private Class<?> findClass(String fieldName) throws NoSuchFieldException,
SecurityException {
if (fieldToClass.containsKey(fieldName)) {
return fieldToClass.get(fieldName);
} else {
Class<?> subclass = resultClass.getDeclaredField(fieldName)
.getType();
if (subclass.equals(List.class) || subclass.equals(Set.class)) {
if (subclass.equals(List.class)) {
listFields.put(fieldName, LinkedList.class);
} else {
listFields.put(fieldName, HashSet.class);
}
Field field = resultClass.getDeclaredField(fieldName);
ParameterizedType genericType = (ParameterizedType) field
.getGenericType();
subclass = (Class<?>) genericType.getActualTypeArguments()[0];
}
fieldToClass.put(fieldName, subclass);
return subclass;
}
}
#SuppressWarnings("unchecked")
private void manageEntities(String fieldName, String aliasName,
Object tupleValue) throws NoSuchFieldException, SecurityException {
Class<?> subclass = findClass(fieldName);
if (!subEntities.containsKey(fieldName)) {
List<Object> list = new ArrayList<Object>();
list.add(new ArrayList<Object>());
list.add(new ArrayList<String>());
list.add(FIELDNAME_INDEX, subclass);
subEntities.put(fieldName, list);
}
((List<Object>) subEntities.get(fieldName).get(TUPE_INDEX))
.add(tupleValue);
((List<String>) subEntities.get(fieldName).get(ALISES_INDEX))
.add(aliasName);
}
private void cleanParams(Object[] tuple, String[] aliases) {
entityTuples = new Object[aliases.length - nestedAliases.size()];
entityAliases = new String[aliases.length - nestedAliases.size()];
for (int j = 0, i = 0; j < aliases.length; j++) {
if (!nestedAliases.contains(aliases[j])) {
entityTuples[i] = tuple[j];
entityAliases[i] = aliases[j];
++i;
}
}
}
#SuppressWarnings({ "unchecked", "rawtypes" })
private void loadSubEntities(Object root) throws HibernateException {
try {
for (String fieldName : subEntities.keySet()) {
Class<?> subclass = (Class<?>) subEntities.get(fieldName).get(
FIELDNAME_INDEX);
ResultTransformer subclassTransformer = new AliasToBeanNestedResultTransformer(
subclass);
Object subObject = subclassTransformer.transformTuple(
((List<Object>) subEntities.get(fieldName).get(0))
.toArray(),
((List<Object>) subEntities.get(fieldName).get(1))
.toArray(new String[0]));
Setter setter = accessor.getSetter(resultClass, fieldName);
if (listFields.containsKey(fieldName)) {
Class<?> collectionClass = listFields.get(fieldName);
Collection subObjectList = (Collection) collectionClass
.newInstance();
subObjectList.add(subObject);
setter.set(root, subObjectList, null);
} else {
setter.set(root, subObject, null);
}
}
} catch (Exception e) {
throw new HibernateException(e);
}
}
private void cleanMaps() {
fieldToClass = new HashMap<String, Class<?>>();
subEntities = new HashMap<String, List<?>>();
nestedAliases = new ArrayList<String>();
listFields = new HashMap<String, Class<?>>();
}
}
I hope it help you.
--------------edit 07/25/15---------------
To group nested list.
public List<? extends Entity<?>> cleanList(
List<? extends Entity<?>> resultList) throws DataException {
List<Entity<?>> entities = new ArrayList<Entity<?>>();
Entity<?> current = null;
try {
for (Entity<?> entity : resultList) {
if (entity.getId() == null) {
continue;
}
if (current == null) {
current = entity;
continue;
}
if (current.getId().equals(entity.getId())) {
append(current, entity);
} else {
entities.add(current);
current = entity;
}
}
if (current != null) {
entities.add(current);
}
cleanSubList(entities);
return entities;
} catch (Exception e) {
throw new DataException(e);
}
}
#SuppressWarnings({ "rawtypes", "unchecked" })
public Set<? extends Entity<?>> cleanList(
Set<? extends Entity<?>> resultList) throws DataException {
List listToClean = new LinkedList();
listToClean.addAll(resultList);
listToClean = cleanList(listToClean);
resultList.clear();
resultList.addAll(listToClean);
return resultList;
}
#SuppressWarnings({ "unchecked", "rawtypes" })
private void append(Entity<?> current, Entity<?> next)
throws IllegalArgumentException, IllegalAccessException {
Field[] fields = current.getClass().getDeclaredFields();
for (Field field : fields) {
if (field.getType().equals(List.class)) {
field.setAccessible(true);
List valueNext = (List) field.get(next);
List valueCurrent = (List) field.get(current);
if (valueNext != null) {
if (valueCurrent != null) {
valueCurrent.addAll(valueNext);
field.set(current, valueCurrent);
} else {
field.set(current, valueNext);
}
}
} else if (field.getType().equals(Set.class)) {
field.setAccessible(true);
Set valueNext = (Set) field.get(next);
Set valueCurrent = (Set) field.get(current);
if (valueNext != null) {
if (valueCurrent != null) {
valueCurrent.addAll(valueNext);
field.set(current, valueCurrent);
} else {
field.set(current, valueNext);
}
}
}
}
}
#SuppressWarnings({ "rawtypes", "unchecked" })
private void cleanSubList(List<? extends Entity<?>> listToClean)
throws IllegalArgumentException, IllegalAccessException,
DataException {
for (Entity<?> entity : listToClean) {
Field[] fields = entity.getClass().getDeclaredFields();
for (Field field : fields) {
if (field.getType().equals(List.class)) {
field.setAccessible(true);
List valueToClean = (List) field.get(entity);
// Throw a thread
if (valueToClean != null) {
valueToClean = cleanList(valueToClean);
field.set(entity, valueToClean);
}
} else if (field.getType().equals(Set.class)) {
field.setAccessible(true);
Set valueToClean = (Set) field.get(entity);
// Throw a thread
if (valueToClean != null) {
valueToClean = cleanList(valueToClean);
field.set(entity, valueToClean);
}
}
}
}
}
To speed up the process I´m suggesting throw a thread in the main process.
This is my Entity interface:
package com.alutiiq.develop.promanagesys.common.entity;
import java.io.Serializable;
/**
* Entity for Hibernate comunications
*
* #author Miguel Resendiz
*
* #param <I>
* Primary key type
*/
public interface Entity<I extends Serializable> extends Serializable {
/**
* Enable poissibility to write generic queries using primary key
*
* #return primary key value for entity
*/
I getId();
void setId(I id);
void setId(String id);
}
Usage example:
criteria.setResultTransformer(new AliasToBeanNestedResultTransformer(
entityClass));
List<Project> projects = criteria.list();
projects = (List<Project>) cleanList(projects);

How to intercept and change sql query dynamically in mybatis

I use mybatis to perform sql queries in my project. I need to intercept sql query before executing to apply some changed dynamically. I've read about #Interseptors like this:
#Intercepts({#Signature(type= Executor.class, method = "query", args = {...})})
public class ExamplePlugin implements Interceptor {
public Object intercept(Invocation invocation) throws Throwable {
return invocation.proceed();
}
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
public void setProperties(Properties properties) {
}
}
And it really intercepts executions, but there is no way to change sql query since appropriate field is not writable. Should I build new instance of whole object manually to just replace sql query? Where is the right place to intercept query execution to change it dynamically? Thank.

I hope it will help you:
#Intercepts( { #Signature(type = Executor.class, method = "query", args = {
MappedStatement.class, Object.class, RowBounds.class,
ResultHandler.class
})
})
public class SelectCountSqlInterceptor2 implements Interceptor
{
public static String COUNT = "_count";
private static int MAPPED_STATEMENT_INDEX = 0;
private static int PARAMETER_INDEX = 1;
#Override
public Object intercept(Invocation invocation) throws Throwable
{
processCountSql(invocation.getArgs());
return invocation.proceed();
}
#SuppressWarnings("rawtypes")
private void processCountSql(final Object[] queryArgs)
{
if (queryArgs[PARAMETER_INDEX] instanceof Map)
{
Map parameter = (Map) queryArgs[PARAMETER_INDEX];
if (parameter.containsKey(COUNT))
{
MappedStatement ms = (MappedStatement) queryArgs[MAPPED_STATEMENT_INDEX];
BoundSql boundSql = ms.getBoundSql(parameter);
String sql = ms.getBoundSql(parameter).getSql().trim();
BoundSql newBoundSql = new BoundSql(ms.getConfiguration(),
getCountSQL(sql), boundSql.getParameterMappings(),
boundSql.getParameterObject());
MappedStatement newMs = copyFromMappedStatement(ms,
new OffsetLimitInterceptor.BoundSqlSqlSource(newBoundSql));
queryArgs[MAPPED_STATEMENT_INDEX] = newMs;
}
}
}
// see: MapperBuilderAssistant
#SuppressWarnings({ "unchecked", "rawtypes" })
private MappedStatement copyFromMappedStatement(MappedStatement ms,
SqlSource newSqlSource)
{
Builder builder = new MappedStatement.Builder(ms.getConfiguration(), ms
.getId(), newSqlSource, ms.getSqlCommandType());
builder.resource(ms.getResource());
builder.fetchSize(ms.getFetchSize());
builder.statementType(ms.getStatementType());
builder.keyGenerator(ms.getKeyGenerator());
// setStatementTimeout()
builder.timeout(ms.getTimeout());
// setParameterMap()
builder.parameterMap(ms.getParameterMap());
// setStatementResultMap()
List<ResultMap> resultMaps = new ArrayList<ResultMap>();
String id = "-inline";
if (ms.getResultMaps() != null)
{
id = ms.getResultMaps().get(0).getId() + "-inline";
}
ResultMap resultMap = new ResultMap.Builder(null, id, Long.class,
new ArrayList()).build();
resultMaps.add(resultMap);
builder.resultMaps(resultMaps);
builder.resultSetType(ms.getResultSetType());
// setStatementCache()
builder.cache(ms.getCache());
builder.flushCacheRequired(ms.isFlushCacheRequired());
builder.useCache(ms.isUseCache());
return builder.build();
}
private String getCountSQL(String sql)
{
String lowerCaseSQL = sql.toLowerCase().replace("\n", " ").replace("\t", " ");
int index = lowerCaseSQL.indexOf(" order ");
if (index != -1)
{
sql = sql.substring(0, index);
}
return "SELECT COUNT(*) from ( select 1 as col_c " + sql.substring(lowerCaseSQL.indexOf(" from ")) + " ) cnt";
}
#Override
public Object plugin(Object target)
{
return Plugin.wrap(target, this);
}
#Override
public void setProperties(Properties properties)
{
}
}

You may consider using a string template library (eg Velocity, Handlebars, Mustache) to help you
As of to date, there is even MyBatis-Velocity (http://mybatis.github.io/velocity-scripting/) to help you to do scripting for the sql.

Depending on the changes you want to make, you may want to use the dynamic sql feature of mybatis 3