Hibernate gives a strange ClassCast exception (using Transformers)

Question

This code:

@Override
public List<FactCodeDto> getAllFactsWithoutParentsAsFactDto() {
    String completeQuery = FactCodeQueries.SELECT_DTO_FROM_FACT_WITH_NO_PARENTS;
    Query query = createHibernateQueryForUnmappedTypeFactDto(completeQuery);

    List<FactCodeDto> factDtoList = query.list(); //line 133
    return factDtoList;
}

calling this method:

private Query createHibernateQueryForUnmappedTypeFactDto(String sqlQuery) throws HibernateException {
    return FactCodeQueries.addScalars(createSQLQuery(sqlQuery)).setResultTransformer(Transformers.aliasToBean(FactCodeDto.class));
}

gives me a ClassCastException -> part of the trace:

Caused by: java.lang.ClassCastException: org.bamboomy.cjr.dto.FactCodeDto cannot be cast to java.util.Map
    at org.hibernate.property.access.internal.PropertyAccessMapImpl$SetterImpl.set(PropertyAccessMapImpl.java:102)
    at org.hibernate.transform.AliasToBeanResultTransformer.transformTuple(AliasToBeanResultTransformer.java:78)
    at org.hibernate.hql.internal.HolderInstantiator.instantiate(HolderInstantiator.java:75)
    at org.hibernate.loader.custom.CustomLoader.getResultList(CustomLoader.java:435)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2423)
    at org.hibernate.loader.Loader.list(Loader.java:2418)
    at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:336)
    at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:1898)
    at org.hibernate.internal.AbstractSessionImpl.list(AbstractSessionImpl.java:318)
    at org.hibernate.internal.SQLQueryImpl.list(SQLQueryImpl.java:125)
    at org.bamboomy.cjr.dao.factcode.FactCodeDAOImpl.getAllFactsWithoutParentsAsFactDto(FactCodeDAOImpl.java:133)

Which is pretty strange because, indeed, if you look up the source code of Hibernate it tries to do this:

@Override
@SuppressWarnings("unchecked")
public void set(Object target, Object value, SessionFactoryImplementor factory) {
    ( (Map) target ).put( propertyName, value ); //line 102
}

Which doesn't make any sense...

target is of type Class and this code tries to cast it to Map,

why does it try to do that???

any pointers are more than welcome...

I'm using Hibernate 5 (and am upgrading from 3)...

edit: I also use Spring (4.2.1.RELEASE; also upgrading) which calls these methods upon deploy, any debugging pointers are most welcome as well...

edit 2: (the whole FactCodeDto class, as requested)

package org.bamboomy.cjr.dto;

import org.bamboomy.cjr.model.FactCode;
import org.bamboomy.cjr.model.FactCodeType;
import org.bamboomy.cjr.utility.FullDateUtil;
import org.bamboomy.cjr.utility.Locales;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;
import org.springframework.util.Assert;

import java.util.*;

@Getter
@Setter
@ToString
public class FactCodeDto extends TreeNodeValue {

    private String cdFact;
    private String cdFactSuffix;
    private Boolean isSupplementCode;
    private Boolean isTitleCode;
    private Boolean mustBeFollowed;

    private Date activeFrom;
    private Date activeTo;
    private Boolean isCode;
    private Long idFact;
    private Long idParent;
    private String type;
    Map<Locale, String> description = new HashMap<Locale, String>(3);

    public FactCodeDto() {
    }

    public FactCodeDto(String prefix, String suffix) {
        super();
        this.cdFact = prefix;
        this.cdFactSuffix = suffix;
    }

    public FactCodeDto(String cdFact, String cdFactSuffix, Boolean isSupplementCode,  Boolean mustBeFollowed) {
        super();
        this.cdFact = cdFact;
        this.cdFactSuffix = cdFactSuffix;
        this.isSupplementCode = isSupplementCode;
        this.mustBeFollowed = mustBeFollowed;

    }

    public FactCodeDto(String cdFact, String cdFactSuffix, Boolean isSupplementCode,  Boolean mustBeFollowed, Long idFact, Long idParent, Boolean isCode, Boolean isTitleCode, Date from, Date to, Map<Locale, String> descriptions,String type) {
        super();
        this.cdFact = cdFact;
        this.cdFactSuffix = cdFactSuffix;
        this.isSupplementCode = isSupplementCode;
        this.mustBeFollowed = mustBeFollowed;
        this.idFact = idFact;
        this.idParent = idParent;
        this.isCode = isCode;
        this.isTitleCode = isTitleCode;
        this.activeFrom = from;
        this.activeTo = to;
        if (descriptions != null) {
            this.description = descriptions;
        }

        this.type = type;

    }

    public FactCodeDto(FactCode fc) {
        this(fc.getPrefix(), fc.getSuffix(), fc.isSupplementCode(), fc.isHasMandatorySupplCodes(), fc.getId(), fc.getParent(), fc.isActualCode(), fc.isTitleCode(), fc.getActiveFrom(), fc.getActiveTo(), fc.getAllDesc(),fc.getType().getCode());
    }

    public String formatCode() {
        return FactCode.formatCode(cdFact, cdFactSuffix);
    }

    public boolean isActive() {
        Date now = new Date(System.currentTimeMillis());
        return FullDateUtil.isBetweenDates(now, this.activeFrom, this.activeTo);

    }

    public void setDescFr(String s) {
        description.put(Locales.FRENCH, s);
    }

    public void setDescNl(String s) {
        description.put(Locales.DUTCH, s);
    }

    public void setDescDe(String s) {
        description.put(Locales.GERMAN, s);
    }

    /**
     * public String toString() {
     * StringBuilder sb = new StringBuilder();
     * sb.append(getIdFact() + ": ")
     * .append(getIdParent() + ": ")
     * .append(" " + cdFact + cdFactSuffix + ": " + (isSupplementCode ? "NO Principal " : "   Principal "))
     * .append((mustBeFollowed ? "    Must Be Followed " : "NOT Must Be Followed "));
     * return sb.toString();
     * }
     */

    public Map<Locale, String> getDescription() {
        return description;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        String fullCode = formatCode();
        result = prime * result + ((fullCode == null) ? 0 : fullCode.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        FactCodeDto other = (FactCodeDto) obj;

        return formatCode().equals(other.formatCode());
    }

    @Override
    public boolean isChildOf(TreeNodeValue value) {
        Assert.notNull(value);
        boolean isChild = false;
        if (value instanceof FactCodeDto) {
            if (this.getIdParent() != null) {
                isChild = this.getIdParent().equals(((FactCodeDto) value).getIdFact());
            }

        }
        return isChild;
    }

    @Override
    public boolean isBrotherOf(TreeNodeValue value) {
        Assert.notNull(value);
        boolean isBrother = false;
        if (value instanceof FactCodeDto) {
            if (this.getIdParent() != null) {
                isBrother = this.getIdParent().equals(((FactCodeDto) value).getIdParent());
            }

        }
        return isBrother;
    }

    @Override
    public boolean isParentOf(TreeNodeValue value) {
        Assert.notNull(value);
        boolean isParent = false;
        if (value instanceof FactCodeDto) {
            isParent = this.getIdFact().equals(((FactCodeDto) value).getIdParent());
        }
        return isParent;
    }


    @Override
    public int compareTo(TreeNodeValue to) {
        if (to instanceof FactCodeDto) {
            return formatCode().compareTo(((FactCodeDto) to).formatCode());
        } else return 1;

    }


    public String getCode() {
        return formatCode();
    }


}

Purveyance

Your target that you are getting is of type : be.fgov.just.cjr.dto.FactCodeDto which is not a map – Louiselouisette

Yeah, I know, but I want to get a List of type FactCodeDto and 'tell' this to hibernate via setResultTransformer(Transformers.aliasToBean(FactCodeDto.class)) but then (for some strange reason) Hibernate internally tries to cast my FactCodeDto.class (target) to a Map... but it shouldn't do that, why does it do that? – Purveyance

why use all this bloat when a simple hql or criteria would solve it? – Budweis

Why are you making it complicated is what I cannot understand. Use a normal HQL query like Query query = session.createQuery("from FactCode as FC"); or whatever your query is and run it. Bloated would be the word. – Apophthegm

@Bamboomy can you show the code for class be.fgov.just.cjr.dto.FactCodeDto? – Deception

Answer 1

In the end it wasn't so hard to find a solution,

I just created my own (custom) ResultTransformer and specified that in the setResultTransformer method:

private Query createHibernateQueryForUnmappedTypeFactDto(String sqlQuery) throws HibernateException {
    return FactCodeQueries.addScalars(createSQLQuery(sqlQuery)).setResultTransformer(new FactCodeDtoResultTransformer());
    //return FactCodeQueries.addScalars(createSQLQuery(sqlQuery)).setResultTransformer(Transformers.aliasToBean(FactCodeDto.class));
}

the code of the custom result transformer:

package org.bamboomy.cjr.dao.factcode;

import org.bamboomy.cjr.dto.FactCodeDto;

import java.util.Date;
import java.util.List;

/**
 * Created by a162299 on 3-11-2015.
 */
public class FactCodeDtoResultTransformer implements org.hibernate.transform.ResultTransformer {

    @Override
    public Object transformTuple(Object[] objects, String[] strings) {

        FactCodeDto result = new FactCodeDto();

        for (int i = 0; i < objects.length; i++) {
            setField(result, strings[i], objects[i]);
        }

        return result;
    }

    private void setField(FactCodeDto result, String string, Object object) {

        if (string.equalsIgnoreCase("cdFact")) {
            result.setCdFact((String) object);
        } else if (string.equalsIgnoreCase("cdFactSuffix")) {
            result.setCdFactSuffix((String) object);
        } else if (string.equalsIgnoreCase("isSupplementCode")) {
            result.setIsSupplementCode((Boolean) object);
        } else if (string.equalsIgnoreCase("isTitleCode")) {
            result.setIsTitleCode((Boolean) object);
        } else if (string.equalsIgnoreCase("mustBeFollowed")) {
            result.setMustBeFollowed((Boolean) object);
        } else if (string.equalsIgnoreCase("activeFrom")) {
            result.setActiveFrom((Date) object);
        } else if (string.equalsIgnoreCase("activeTo")) {
            result.setActiveTo((Date) object);
        } else if (string.equalsIgnoreCase("descFr")) {
            result.setDescFr((String) object);
        } else if (string.equalsIgnoreCase("descNl")) {
            result.setDescNl((String) object);
        } else if (string.equalsIgnoreCase("descDe")) {
            result.setDescDe((String) object);
        } else if (string.equalsIgnoreCase("type")) {
            result.setType((String) object);
        } else if (string.equalsIgnoreCase("idFact")) {
            result.setIdFact((Long) object);
        } else if (string.equalsIgnoreCase("idParent")) {
            result.setIdParent((Long) object);
        } else if (string.equalsIgnoreCase("isCode")) {
            result.setIsCode((Boolean) object);
        } else {
            throw new RuntimeException("unknown field");
        }

    }

    @Override
    public List transformList(List list) {
        return list;
    }
}

in hibernate 3 you could set Aliasses to queries but you can't do that anymore in hibernate 5 (correct me if I'm wrong) hence the aliasToBean is something you only can use when actually using aliasses; which I didn't, hence the exception.

Purveyance

It is possible to use aliases, see my answer https://mcmap.net/q/774462/-hibernate-gives-a-strange-classcast-exception-using-transformers – Jural

And it is possible to make a more simply and universal transformer, using the reflection. – Jural

Answer 2

I found that AliasToBean has changed in Hibernate 5. For me adding getter for my field fixed the problem.

Tinkle

for me under similar conditions I was need to change field name from let say zipcode to ZipCode (aka camel case) and rename setter method accordingly. but anyway, exception text may confuse.. – Derward

Answer 3

This exception occurs when the setters and getters are not mapped correctly to the column names. Make sure you have the correct getters and setters for the query(Correct names and correct datatypes). Read more about it here:

http://javahonk.com/java-lang-classcastexception-com-wfs-otc-datamodels-imagineexpirymodel-cannot-cast-java-util-map/

Aluino

This answer doesn't provide a solution, even with correct mapping the cast wouldn't work. – Purveyance

Answer 4

I do some investigation on this question. The problem is that Hibernate converts aliases for column names to upper case — cdFact becomesCDFACT.

Read for a more deeply explanation and workaround here: mapping Hibernate query results to custom class?

Jural

Answer 5

Im my case :

 => write sql query and try to map result to Class List 
 => Use "Transformers.aliasToBean" 
 => get Error "cannot be cast to java.util.Map"

Solution :

      => just put \" before and after query aliases 
      ex: 
      "select first_name as \"firstName\" from test"

The problem is that Hibernate converts aliases for column names to upper case or lower case

Idiom

Answer 6

I solved it by defining my own custom transformer as given below -

import org.hibernate.transform.BasicTransformerAdapter;   

public class FluentHibernateResultTransformer extends BasicTransformerAdapter {

    private static final long serialVersionUID = 6825154815776629666L;

    private final Class<?> resultClass;

    private NestedSetter[] setters;

    public FluentHibernateResultTransformer(Class<?> resultClass) {
        this.resultClass = resultClass;
    }

    @Override
    public Object transformTuple(Object[] tuple, String[] aliases) {
        createCachedSetters(resultClass, aliases);

        Object result = ClassUtils.newInstance(resultClass);

        for (int i = 0; i < aliases.length; i++) {
            setters[i].set(result, tuple[i]);
        }

        return result;
    }

    private void createCachedSetters(Class<?> resultClass, String[] aliases) {
        if (setters == null) {
            setters = createSetters(resultClass, aliases);
        }
    }

    private static NestedSetter[] createSetters(Class<?> resultClass, String[] aliases) {
        NestedSetter[] result = new NestedSetter[aliases.length];

        for (int i = 0; i < aliases.length; i++) {
            result[i] = NestedSetter.create(resultClass, aliases[i]);
        }

        return result;
    }
}

And used this way inside the repository method -

@Override
    public List<WalletVO> getWalletRelatedData(WalletRequest walletRequest,
            Set<String> requiredVariablesSet) throws GenericBusinessException {
        String query = getWalletQuery(requiredVariablesSet);

        try {
            if (query != null && !query.isEmpty()) {
                SQLQuery sqlQuery = mEntityManager.unwrap(Session.class).createSQLQuery(query);
                return sqlQuery.setResultTransformer(new FluentHibernateResultTransformer(WalletVO.class))
                        .list();
            }
        } catch (Exception ex) {
            exceptionThrower.throwDatabaseException(null, false);
        }

        return Collections.emptyList();
    }

It worked perfectly !!!

Moise

Answer 7

Try putting Column names and field names both in capital letters.

Wall

Answer 8

This exception occurs when the class that you specified in the AliasToBeanResultTransformer does not have getter for the corresponding columns. Although the exception details from the hibernate are misleading.

Minhminho