I'm using org.hibernate.criterion.Example.create to create my query from my Entity object. Everything is fine, but using this method the SQL is only created with AND clause between the restrictions.
Is it possible to use org.hibernate.criterion.Example.create but with OR clause?
The short answer is no, you can not do it, but you can implement a OrExample, it's pretty easy, only check the source code of the Example and change the and for or (see sourcecode line 329). Since the methods are protected, you can extend it and override just the necesary.
Something like this:
public class OrExample extends org.hibernate.criterion.Example {
#Override
protected void appendPropertyCondition(
String propertyName,
Object propertyValue,
Criteria criteria,
CriteriaQuery cq,
StringBuffer buf)
throws HibernateException {
Criterion crit;
if ( propertyValue!=null ) {
boolean isString = propertyValue instanceof String;
if ( isLikeEnabled && isString ) {
crit = new LikeExpression(
propertyName,
( String ) propertyValue,
matchMode,
escapeCharacter,
isIgnoreCaseEnabled
);
}
else {
crit = new SimpleExpression( propertyName, propertyValue, "=", isIgnoreCaseEnabled && isString );
}
}
else {
crit = new NullExpression(propertyName);
}
String critCondition = crit.toSqlString(criteria, cq);
if ( buf.length()>1 && critCondition.trim().length()>0 ) buf.append(" or ");
buf.append(critCondition);
}
See the or instead of the original and.
Yes, you can
session.createCriteria(Person.class) .add(Restrictions.disjunction() .add(Restrictions.eq("name", "James")) .add(Restrictions.eq("age", 20)) );
In the example above, class Person would have properties name and age and you would be selecting those people with name = "James" or age = 20.
an old post from SO may be helpful: Hibernate Criteria Restrictions AND / OR combination
Criteria criteria = getSession().createCriteria(clazz);
Criterion rest1= Restrictions.and(Restrictions.eq("A", "X"),
Restrictions.in("B", Arrays.asList("X","Y")));
Criterion rest2= Restrictions.and(Restrictions.eq("A", "Y"),
Restrictions.eq("B", "Z"));
criteria.add(Restrictions.or(rest1, rest2));
Related
Here's what I did:
String textField1 = fastVectorHighlighter.getBestFragment(fastVectorHighlighter.getFieldQuery(query), indexReader, docId, SearchItem.FIELD_TEXT_FIELD1, DEFAULT_FRAGMENT_LENGTH);
Here's the query:
((FIELD_TEXT_FIELD1:十五*)^4.0) (FIELD_TEXT_FIELD3:十五*)
The original text is correct(indexReader.document(docId).get(SearchItem.FIELD_TEXT_FIELD3) is correct.), and definitely contains characters in query.
Here's how I index textField1 :
Field textField1 = new TextField(SearchItem.FIELD_TEXT_FIELD1, "", Field.Store.YES);
Problem solved!
It turns out, I need to change
fastVectorHighlighter.getFieldQuery(query)
to
fastVectorHighlighter.getFieldQuery(query, indexReader)
Follow the code into FieldQuery#flatten, we will find Lucene doesn't deal with PrefixQuery the normal way：
} else if (sourceQuery instanceof CustomScoreQuery) {
final Query q = ((CustomScoreQuery) sourceQuery).getSubQuery();
if (q != null) {
flatten( applyParentBoost( q, sourceQuery ), reader, flatQueries);
}
} else if (reader != null) { // <<====== Here it is!
Query query = sourceQuery;
if (sourceQuery instanceof MultiTermQuery) {
MultiTermQuery copy = (MultiTermQuery) sourceQuery.clone();
copy.setRewriteMethod(new MultiTermQuery.TopTermsScoringBooleanQueryRewrite(MAX_MTQ_TERMS));
query = copy;
}
Query rewritten = query.rewrite(reader);
if (rewritten != query) {
// only rewrite once and then flatten again - the rewritten query could have a speacial treatment
// if this method is overwritten in a subclass.
flatten(rewritten, reader, flatQueries);
}
We can see it needs a IndexReader for PrefixQuery, FuzzyQuery etc.
i want add some more complicated selections as below on date coloumn
select TO_DATE ('04-JAN-2015','DD-MM-YYYY'), to_char(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'FMDAY') day,
(case when to_char(trunc(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'mm'), 'FMDAY') = 'SUNDAY' then to_number(to_char(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'W'))
else ceil((to_char(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'dd') + 1 - to_char(next_day(trunc(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'mm'), 'SUNDAY'), 'dd'))/7)
end)+1 week_no
from dual
here breakupFields is list of string which leads to date column
final QueryBuilder distinctDateTimeFilter = new QueryBuilder() {
final List<String> breakupFields = new ArrayList<String>(fields.length);
for (final String f : fields)
if (!Strings.isEmpty(f)) {
breakupFields.add(f);
}
}
final QueryBuilder distinctDateTimeFilter = new QueryBuilder() {
#Override
public CriteriaQuery buildQuery(CriteriaBuilder cb, CriteriaQuery query, Predicate p, List orders, Root rt) {
Expression selection = null;
selection = cb.function("TO_CHAR", String.class, cb.sum(CriteriaQueryUtils.getPath(rt, breakupFields), cb.literal(miliSecToAdd)),
cb.literal("W-MM-YYYY"));
return query.select(selection).distinct(true).where(p).orderBy(orders);
}
}
final List<Object> objs = new ArrayList<Object>(ds.executeQuery(classObject, Object.class, distinctDateTimeFilter, ef, session,
SuperUserSecurityContext.class));
Can any one suggest how to add
(case when to_char(trunc(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'mm'), 'FMDAY') = 'SUNDAY' then to_number(to_char(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'W'))
else ceil((to_char(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'dd') + 1 - to_char(next_day(trunc(TO_DATE ('04-JAN-2015','DD-MM-YYYY'), 'mm'), 'SUNDAY'), 'dd'))/7)
end)+1 to criteria builder
You can introduce a column in your Entity marked as
#Formula(value="the expression")
See more here and use the column in the queries.
Or you can define native SQL query with the desired entity class mapped and use fuly native SQL.
Given a Lucene search query like: +(letter:A letter:B letter:C) +(style:Capital), how can I tell which of the three letters actually matched any given document? I don't care where they match, or how many times they match, I just need to know whether they matched.
The intent is to take the initial query ("A B C"), remove the terms which successfully matched (A and B), and then do further processing on the remainder (C).
Although the sample is in c#, Lucene APIs are very similar(some upper/lower case differences). I don't think it would be hard to translate to java.
This is the usage
List<Term> terms = new List<Term>(); //will be filled with non-matched terms
List<Term> hitTerms = new List<Term>(); //will be filled with matched terms
GetHitTerms(query, searcher,docId, hitTerms,terms);
And here is the method
void GetHitTerms(Query query,IndexSearcher searcher,int docId,List<Term> hitTerms,List<Term>rest)
{
if (query is TermQuery)
{
if (searcher.Explain(query, docId).IsMatch() == true)
hitTerms.Add((query as TermQuery).GetTerm());
else
rest.Add((query as TermQuery).GetTerm());
return;
}
if (query is BooleanQuery)
{
BooleanClause[] clauses = (query as BooleanQuery).GetClauses();
if (clauses == null) return;
foreach (BooleanClause bc in clauses)
{
GetHitTerms(bc.GetQuery(), searcher, docId,hitTerms,rest);
}
return;
}
if (query is MultiTermQuery)
{
if (!(query is FuzzyQuery)) //FuzzQuery doesn't support SetRewriteMethod
(query as MultiTermQuery).SetRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE);
GetHitTerms(query.Rewrite(searcher.GetIndexReader()), searcher, docId,hitTerms,rest);
}
}
As answer given by #L.B, Here is the converted code of JAVA which works for me:
void GetHitTerms(Query query,IndexSearcher searcher,int docId,List<Term> hitTerms,List<Term>rest) throws IOException
{
if(query instanceof TermQuery )
{
if (searcher.explain(query, docId).isMatch())
hitTerms.add(((TermQuery) query).getTerm());
else
rest.add(((TermQuery) query).getTerm());
return;
}
if(query instanceof BooleanQuery )
{
for (BooleanClause clause : (BooleanQuery)query) {
GetHitTerms(clause.getQuery(), searcher, docId,hitTerms,rest);
}
return;
}
if (query instanceof MultiTermQuery)
{
if (!(query instanceof FuzzyQuery)) //FuzzQuery doesn't support SetRewriteMethod
((MultiTermQuery)query).setRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE);
GetHitTerms(query.rewrite(searcher.getIndexReader()), searcher, docId,hitTerms,rest);
}
}
I basically used the same approach as #L.B, but updated it for usage for the newest Lucene Version 7.4.0. Note: FuzzyQuery now supports .setRewriteMethod (that's why I removed the if).
I also included handling for BoostQuerys and saved the words that were found by Lucene in a HashSet to avoid duplicates instead of the Terms.
private void saveHitWordInList(Query query, IndexSearcher indexSearcher,
int docId, HashSet<String> hitWords) throws IOException {
if (query instanceof TermQuery)
if (indexSearcher.explain(query, docId).isMatch())
hitWords.add(((TermQuery) query).getTerm().toString().split(":")[1]);
if (query instanceof BooleanQuery) {
for (BooleanClause clause : (BooleanQuery) query) {
saveHitWordInList(clause.getQuery(), indexSearcher, docId, hitWords);
}
}
if (query instanceof MultiTermQuery) {
((MultiTermQuery) query)
.setRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_REWRITE);
saveHitWordInList(query.rewrite(indexSearcher.getIndexReader()),
indexSearcher, docId, hitWords);
}
if (query instanceof BoostQuery)
saveHitWordInList(((BoostQuery) query).getQuery(), indexSearcher, docId,
hitWords);
}
Here is a simplified and non-recursive version with Lucene.NET 4.8.
Unverified, but this should also work on Lucene.NET 3.x
IEnumerable<Term> GetHitTermsForDoc(Query query, IndexSearcher searcher, int docId)
{
//Rewrite query into simpler internal form, required for ExtractTerms
var simplifiedQuery = query.Rewrite(searcher.IndexReader);
HashSet<Term> queryTerms = new HashSet<Term>();
simplifiedQuery.ExtractTerms(queryTerms);
List<Term> hitTerms = new List<Term>();
foreach (var term in queryTerms)
{
var termQuery = new TermQuery(term);
var explanation = searcher.Explain(termQuery, docId);
if (explanation.IsMatch)
{
hitTerms.Add(term);
}
}
return hitTerms;
}
You could use a cached filter for each of the individual terms, and quickly check each doc id against their BitSets.
Is there a way to get the (to-be-generated) SQL from a Hibernate Criteria?
Ideally, I would have something like:
Criteria criteria = session.createCriteria(Operator.class);
... build up the criteria ...
... and then do something like ...
String sql = criteria.toSql()
(But this of course does not exist)
The idea would then be to use the SQL as part of a huge 'MINUS' query (I need to find the differences between 2 identical schemas - identical in structure, not in data - and the MINUS is not supported by Hibernate)
(BTW I know I can check the SQL from the log files)
Here's "another" way to get the SQL :
CriteriaImpl criteriaImpl = (CriteriaImpl)criteria;
SessionImplementor session = criteriaImpl.getSession();
SessionFactoryImplementor factory = session.getFactory();
CriteriaQueryTranslator translator=new CriteriaQueryTranslator(factory,criteriaImpl,criteriaImpl.getEntityOrClassName(),CriteriaQueryTranslator.ROOT_SQL_ALIAS);
String[] implementors = factory.getImplementors( criteriaImpl.getEntityOrClassName() );
CriteriaJoinWalker walker = new CriteriaJoinWalker((OuterJoinLoadable)factory.getEntityPersister(implementors[0]),
translator,
factory,
criteriaImpl,
criteriaImpl.getEntityOrClassName(),
session.getLoadQueryInfluencers() );
String sql=walker.getSQLString();
I've done something like this using Spring AOP so I could grab the sql, parameters, errors, and execution time for any query run in the application whether it was HQL, Criteria, or native SQL.
This is obviously fragile, insecure, subject to break with changes in Hibernate, etc, but it illustrates that it's possible to get the SQL:
CriteriaImpl c = (CriteriaImpl)query;
SessionImpl s = (SessionImpl)c.getSession();
SessionFactoryImplementor factory = (SessionFactoryImplementor)s.getSessionFactory();
String[] implementors = factory.getImplementors( c.getEntityOrClassName() );
CriteriaLoader loader = new CriteriaLoader((OuterJoinLoadable)factory.getEntityPersister(implementors[0]),
factory, c, implementors[0], s.getEnabledFilters());
Field f = OuterJoinLoader.class.getDeclaredField("sql");
f.setAccessible(true);
String sql = (String)f.get(loader);
Wrap the entire thing in a try/catch and use at your own risk.
For those using NHibernate, this is a port of [ram]'s code
public static string GenerateSQL(ICriteria criteria)
{
NHibernate.Impl.CriteriaImpl criteriaImpl = (NHibernate.Impl.CriteriaImpl)criteria;
NHibernate.Engine.ISessionImplementor session = criteriaImpl.Session;
NHibernate.Engine.ISessionFactoryImplementor factory = session.Factory;
NHibernate.Loader.Criteria.CriteriaQueryTranslator translator =
new NHibernate.Loader.Criteria.CriteriaQueryTranslator(
factory,
criteriaImpl,
criteriaImpl.EntityOrClassName,
NHibernate.Loader.Criteria.CriteriaQueryTranslator.RootSqlAlias);
String[] implementors = factory.GetImplementors(criteriaImpl.EntityOrClassName);
NHibernate.Loader.Criteria.CriteriaJoinWalker walker = new NHibernate.Loader.Criteria.CriteriaJoinWalker(
(NHibernate.Persister.Entity.IOuterJoinLoadable)factory.GetEntityPersister(implementors[0]),
translator,
factory,
criteriaImpl,
criteriaImpl.EntityOrClassName,
session.EnabledFilters);
return walker.SqlString.ToString();
}
If you are using Hibernate 3.6 you can use the code in the accepted answer (provided by Brian Deterling) with slight modification:
CriteriaImpl c = (CriteriaImpl) criteria;
SessionImpl s = (SessionImpl) c.getSession();
SessionFactoryImplementor factory = (SessionFactoryImplementor) s.getSessionFactory();
String[] implementors = factory.getImplementors(c.getEntityOrClassName());
LoadQueryInfluencers lqis = new LoadQueryInfluencers();
CriteriaLoader loader = new CriteriaLoader((OuterJoinLoadable) factory.getEntityPersister(implementors[0]), factory, c, implementors[0], lqis);
Field f = OuterJoinLoader.class.getDeclaredField("sql");
f.setAccessible(true);
String sql = (String) f.get(loader);
I like this if you want to get just some parts of the query:
new CriteriaQueryTranslator(
factory,
executableCriteria,
executableCriteria.getEntityOrClassName(),
CriteriaQueryTranslator.ROOT_SQL_ALIAS)
.getWhereCondition();
For instance something like this:
String where = new CriteriaQueryTranslator(
factory,
executableCriteria,
executableCriteria.getEntityOrClassName(),
CriteriaQueryTranslator.ROOT_SQL_ALIAS)
.getWhereCondition();
String sql = "update my_table this_ set this_.status = 0 where " + where;
Here is a method I used and worked for me
public static String toSql(Session session, Criteria criteria){
String sql="";
Object[] parameters = null;
try{
CriteriaImpl c = (CriteriaImpl) criteria;
SessionImpl s = (SessionImpl)c.getSession();
SessionFactoryImplementor factory = (SessionFactoryImplementor)s.getSessionFactory();
String[] implementors = factory.getImplementors( c.getEntityOrClassName() );
CriteriaLoader loader = new CriteriaLoader((OuterJoinLoadable)factory.getEntityPersister(implementors[0]), factory, c, implementors[0], s.getEnabledFilters());
Field f = OuterJoinLoader.class.getDeclaredField("sql");
f.setAccessible(true);
sql = (String)f.get(loader);
Field fp = CriteriaLoader.class.getDeclaredField("traslator");
fp.setAccessible(true);
CriteriaQueryTranslator translator = (CriteriaQueryTranslator) fp.get(loader);
parameters = translator.getQueryParameters().getPositionalParameterValues();
}
catch(Exception e){
throw new RuntimeException(e);
}
if (sql !=null){
int fromPosition = sql.indexOf(" from ");
sql = "SELECT * "+ sql.substring(fromPosition);
if (parameters!=null && parameters.length>0){
for (Object val : parameters) {
String value="%";
if(val instanceof Boolean){
value = ((Boolean)val)?"1":"0";
}else if (val instanceof String){
value = "'"+val+"'";
}
sql = sql.replaceFirst("\\?", value);
}
}
}
return sql.replaceAll("left outer join", "\nleft outer join").replace(" and ", "\nand ").replace(" on ", "\non ");
}
For anyone wishing to do this in a single line (e.g in the Display/Immediate window, a watch expression or similar in a debug session), the following will do so and "pretty print" the SQL:
new org.hibernate.jdbc.util.BasicFormatterImpl().format((new org.hibernate.loader.criteria.CriteriaJoinWalker((org.hibernate.persister.entity.OuterJoinLoadable)((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory().getEntityPersister(((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory().getImplementors(((org.hibernate.impl.CriteriaImpl)crit).getEntityOrClassName())[0]),new org.hibernate.loader.criteria.CriteriaQueryTranslator(((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory(),((org.hibernate.impl.CriteriaImpl)crit),((org.hibernate.impl.CriteriaImpl)crit).getEntityOrClassName(),org.hibernate.loader.criteria.CriteriaQueryTranslator.ROOT_SQL_ALIAS),((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory(),(org.hibernate.impl.CriteriaImpl)crit,((org.hibernate.impl.CriteriaImpl)crit).getEntityOrClassName(),((org.hibernate.impl.CriteriaImpl)crit).getSession().getEnabledFilters())).getSQLString());
...or here's an easier to read version:
new org.hibernate.jdbc.util.BasicFormatterImpl().format(
(new org.hibernate.loader.criteria.CriteriaJoinWalker(
(org.hibernate.persister.entity.OuterJoinLoadable)
((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory().getEntityPersister(
((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory().getImplementors(
((org.hibernate.impl.CriteriaImpl)crit).getEntityOrClassName())[0]),
new org.hibernate.loader.criteria.CriteriaQueryTranslator(
((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory(),
((org.hibernate.impl.CriteriaImpl)crit),
((org.hibernate.impl.CriteriaImpl)crit).getEntityOrClassName(),
org.hibernate.loader.criteria.CriteriaQueryTranslator.ROOT_SQL_ALIAS),
((org.hibernate.impl.CriteriaImpl)crit).getSession().getFactory(),
(org.hibernate.impl.CriteriaImpl)crit,
((org.hibernate.impl.CriteriaImpl)crit).getEntityOrClassName(),
((org.hibernate.impl.CriteriaImpl)crit).getSession().getEnabledFilters()
)
).getSQLString()
);
Notes:
The answer is based on the solution posted by ramdane.i.
It assumes the Criteria object is named crit. If named differently, do a search and replace.
It assumes the Hibernate version is later than 3.3.2.GA but earlier than 4.0 in order to use BasicFormatterImpl to "pretty print" the HQL. If using a different version, see this answer for how to modify. Or perhaps just remove the pretty printing entirely as it's just a "nice to have".
It's using getEnabledFilters rather than getLoadQueryInfluencers() for backwards compatibility since the latter was introduced in a later version of Hibernate (3.5???)
It doesn't output the actual parameter values used if the query is parameterized.
This answer is based on user3715338's answer (with a small spelling error corrected) and mixed with Michael's answer for Hibernate 3.6 - based on the accepted answer from Brian Deterling. I then extended it (for PostgreSQL) with a couple more types replacing the questionmarks:
public static String toSql(Criteria criteria)
{
String sql = "";
Object[] parameters = null;
try
{
CriteriaImpl criteriaImpl = (CriteriaImpl) criteria;
SessionImpl sessionImpl = (SessionImpl) criteriaImpl.getSession();
SessionFactoryImplementor factory = sessionImpl.getSessionFactory();
String[] implementors = factory.getImplementors(criteriaImpl.getEntityOrClassName());
OuterJoinLoadable persister = (OuterJoinLoadable) factory.getEntityPersister(implementors[0]);
LoadQueryInfluencers loadQueryInfluencers = new LoadQueryInfluencers();
CriteriaLoader loader = new CriteriaLoader(persister, factory,
criteriaImpl, implementors[0].toString(), loadQueryInfluencers);
Field f = OuterJoinLoader.class.getDeclaredField("sql");
f.setAccessible(true);
sql = (String) f.get(loader);
Field fp = CriteriaLoader.class.getDeclaredField("translator");
fp.setAccessible(true);
CriteriaQueryTranslator translator = (CriteriaQueryTranslator) fp.get(loader);
parameters = translator.getQueryParameters().getPositionalParameterValues();
}
catch (Exception e)
{
throw new RuntimeException(e);
}
if (sql != null)
{
int fromPosition = sql.indexOf(" from ");
sql = "\nSELECT * " + sql.substring(fromPosition);
if (parameters != null && parameters.length > 0)
{
for (Object val : parameters)
{
String value = "%";
if (val instanceof Boolean)
{
value = ((Boolean) val) ? "1" : "0";
}
else if (val instanceof String)
{
value = "'" + val + "'";
}
else if (val instanceof Number)
{
value = val.toString();
}
else if (val instanceof Class)
{
value = "'" + ((Class) val).getCanonicalName() + "'";
}
else if (val instanceof Date)
{
SimpleDateFormat sdf = new SimpleDateFormat(
"yyyy-MM-dd HH:mm:ss.SSS");
value = "'" + sdf.format((Date) val) + "'";
}
else if (val instanceof Enum)
{
value = "" + ((Enum) val).ordinal();
}
else
{
value = val.toString();
}
sql = sql.replaceFirst("\\?", value);
}
}
}
return sql.replaceAll("left outer join", "\nleft outer join").replaceAll(
" and ", "\nand ").replaceAll(" on ", "\non ").replaceAll("<>",
"!=").replaceAll("<", " < ").replaceAll(">", " > ");
}
Michael's answer is perfect, just the imports it is missing:
import java.lang.reflect.Field;
import org.hibernate.Criteria;
import org.hibernate.criterion.DetachedCriteria;
import org.hibernate.criterion.Order;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Property;
import org.hibernate.criterion.Restrictions;
import org.hibernate.criterion.Subqueries;
import org.hibernate.engine.spi.LoadQueryInfluencers;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.internal.CriteriaImpl;
import org.hibernate.internal.SessionImpl;
import org.hibernate.loader.OuterJoinLoader;
import org.hibernate.loader.criteria.CriteriaLoader;
import org.hibernate.persister.entity.OuterJoinLoadable;
CriteriaImpl c = (CriteriaImpl) criteria;
SessionImpl s = (SessionImpl) c.getSession();
SessionFactoryImplementor factory = (SessionFactoryImplementor) s.getSessionFactory();
String[] implementors = factory.getImplementors(c.getEntityOrClassName());
LoadQueryInfluencers lqis = new LoadQueryInfluencers();
CriteriaLoader loader = new CriteriaLoader((OuterJoinLoadable) factory.getEntityPersister(implementors[0]), factory, c, implementors[0], lqis);
Field f = OuterJoinLoader.class.getDeclaredField("sql");
f.setAccessible(true);
String sql = (String) f.get(loader);
I have an entity loaded by Hibernate (via EntityManager):
User u = em.load(User.class, id)
This class is audited by Hibernate Envers. How can I load the previous version of a User entity?
Here's another version that finds the previous revision relative to a "current" revision number, so it can be used even if the entity you're looking at isn't the latest revision. It also handles the case where there isn't a prior revision. (em is assumed to be a previously-populated EntityManager)
public static User getPreviousVersion(User user, int current_rev) {
AuditReader reader = AuditReaderFactory.get(em);
Number prior_revision = (Number) reader.createQuery()
.forRevisionsOfEntity(User.class, false, true)
.addProjection(AuditEntity.revisionNumber().max())
.add(AuditEntity.id().eq(user.getId()))
.add(AuditEntity.revisionNumber().lt(current_rev))
.getSingleResult();
if (prior_revision != null)
return (User) reader.find(User.class, user.getId(), prior_revision);
else
return null
}
This can be generalized to:
public static T getPreviousVersion(T entity, int current_rev) {
AuditReader reader = AuditReaderFactory.get(JPA.em());
Number prior_revision = (Number) reader.createQuery()
.forRevisionsOfEntity(entity.getClass(), false, true)
.addProjection(AuditEntity.revisionNumber().max())
.add(AuditEntity.id().eq(((Model) entity).id))
.add(AuditEntity.revisionNumber().lt(current_rev))
.getSingleResult();
if (prior_revision != null)
return (T) reader.find(entity.getClass(), ((Model) entity).id, prior_revision);
else
return null
}
The only tricky bit with this generalization is getting the entity's id. Because I'm using the Play! framework, I can exploit the fact that all entities are Models and use ((Model) entity).id to get the id, but you'll have to adjust this to suit your environment.
maybe this then (from AuditReader docs)
AuditReader reader = AuditReaderFactory.get(entityManager);
User user_rev1 = reader.find(User.class, user.getId(), 1);
List<Number> revNumbers = reader.getRevisions(User.class, user_rev1);
User user_previous = reader.find(User.class, user_rev1.getId(),
revNumbers.get(revNumbers.size()-1));
(I'm very new to this, not sure if I have all the syntax right, maybe the size()-1 should be size()-2?)
I think it would be this:
final AuditReader reader = AuditReaderFactory.get( entityManagerOrSession );
// This could probably be declared as Long instead of Object
final Object pk = userCurrent.getId();
final List<Number> userRevisions = reader.getRevisions( User.class, pk );
final int revisionCount = userRevision.size();
final Number previousRevision = userRevisions.get( revisionCount - 2 );
final User userPrevious = reader.find( User.class, pk, previousRevision );
Building off of the excellent approach of #brad-mace, I have made the following changes:
You should pass in your EntityClass and Id instead of hardcoding and assuming the Model.
Don't hardcode your EntityManager.
There is no point setting selectDeleted, because a deleted record can never be returned as the previous revision.
Calling get single result with throw and exception if no results or more than 1 result is found, so either call resultlist or catch the exception (this solution calls getResultList with maxResults = 1)
Get the revision, type, and entity in one transaction (remove the projection, use orderBy and maxResults, and query for the Object[3] )
So here's another solution:
public static <T> T getPreviousRevision(EntityManager entityManager, Class<T> entityClass, Object entityId, int currentRev) {
AuditReader reader = AuditReaderFactory.get(entityManager);
List<Object[]> priorRevisions = (List<Object[]>) reader.createQuery()
.forRevisionsOfEntity(entityClass, false, false)
.add(AuditEntity.id().eq(entityId))
.add(AuditEntity.revisionNumber().lt(currentRev))
.addOrder(AuditEntity.revisionNumber().desc())
.setMaxResults(1)
.getResultList();
if (priorRevisions.size() == 0) {
return null;
}
// The list contains a single Object[] with entity, revinfo, and type
return (T) priorRevision.get(0)[0];
}
From the docs:
AuditReader reader = AuditReaderFactory.get(entityManager);
User user_rev1 = reader.find(User.class, user.getId(), 1);