Problems using Hibernate Criteria API

[Kristofer Hindersson]

Hi, I have a class Person with these attributes: firstname:String, lastname:String and birthdayate.

I'm trying to use the Hibernate Criteria API by creating a new Person and setting some of the attributes with values that I want to query the database against.

Person person = new Person();
person.setFirstname("Paul");

I then create a new Example thus:

Example example = Example.create(person);
example.enableLike();
example.excludeZeroes();

...after which I create the Criteria:

...createCriteria(Person.class).add(example).list();

The problem is that this doesn't return any result (empty list) even though I know for certain that there is row where the firstname-column contains 'Paul'. What am I doing wrong here? Have I completely misunderstood the usage of Example together with Criteria?

[Cameron Wallace McKenzie]

No, it looks like you're doing it correctly.

Why not try a query like the following, without the Example. The following should just return all the data from the database. See if you can do a criteria query without the Example first. Then, when that works, let's move onto seeing if the Example class is the problem.

  Criteria crit = 
          HibernateUtil.getSession()
                  .createCriteria(Person.clas);
  crit.setFirstResult(startIndex);
  crit.setFetchSize(fetchSize);
  return crit.list();

Whadya think?

[Kristofer Hindersson]

Cameron Wallace McKenzie wrote:No, it looks like you're doing it correctly.

Why not try a query like the following, without the Example. The following should just return all the data from the database. See if you can do a criteria query without the Example first. Then, when that works, let's move onto seeing if the Example class is the problem.

  Criteria crit = 
          HibernateUtil.getSession()
                  .createCriteria(Person.clas);
  crit.setFirstResult(startIndex);
  crit.setFetchSize(fetchSize);
  return crit.list();

Whadya think?

Well if I use FetchMode START or ANYWHERE, or if I use the default (EXACT) and sets more than one attribute in the Person-instance, qbe will work. But if I only set the firstname-attribute before creating the example, the Criteria won't return any result. I wonder if this has anything to do with that I have more than one 'Paul' present in the database?

[Kuladip Yadav]

Can you check query generated by hibernate for both scenario ?
By looking at both queries you will come to know exact problem.

[Kristofer Hindersson]

Thanks for the replies. I got it working by rebuilding the whole project (Spring MVC). I have no idea what I did differently but now I have another problem:

I have the following classes:

@Entity
@Table(name="people")
public class Person {
	
	private Integer id;
	private String name;
	private List<Profile> profiles;
	
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	public Integer getId() {
		return this.id;
	}
	
	public void setId(Integer id) {
		this.id = id;
	}
	
	public String getName() {
		return this.name;
	}
	
	public void setString(String name) {
		this.name = name;
	}
	
	@OneToMany(mappedBy="person", cascade=CascadeType.ALL)
	public List<Profile> getProfiles() {
		return this.profiles;
	}
	
	public void setProfiles(List<Profile> profiles) {
		this.profiles = profiles;
	}
}

@Entity
@Table(name="competences")
public class Competence {
	
	private Integer id;
	private String name;
	private List<Profile> profiles;

	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}

	@OneToMany(mappedBy="competence", cascade=CascadeType.ALL)
	public List<Profile> getProfiles() {
		return this.profiles;
	}

	public void setProfiles(List<Profile> profiles) {
		this.profiles = profiles;
	}
}

@Entity
@Table(name="profiles")
public class Profile {
	private Integer id;
	private double experience;
	Person person;
	Competence competence;
	
	@Id
	@GeneratedValue(strategy=GenerationType.AUTO)
	public Integer getId() {
		return this.id;
	}
	
	public void setId(Integer id) {
		this.id = id;
	}
	
	public double getExperience() {
		return this.experience;
	}
	
	public void setExperience(double experience) {
		this.experience = experience;
	}
	
	@ManyToOne
	@JoinColumn(name="person_id")
	public Person getPerson() {
		return this.person;
	}
	
	public void setPerson(Person person) {
		this.person = person;
	}
	
	@ManyToOne
	@JoinColumn(name="competence_id")
	public Competence getCompetence() {
		return this.competence;
	}
	
	public void setCompetence(Competence competence) {
		this.competence = competence;
	}	
}

Here's my Criteria method in my ServiceImpl:

	@SuppressWarnings("unchecked")
	@Transactional(readOnly=true)
	public List<Person> findPeople(Person person, Competence competence) throws DataAccessException {	
		List<Profile> profiles = sessionFactory.getCurrentSession().createCriteria(Profile.class)
		.add(Restrictions.or(Restrictions.like("person", person), Restrictions.eq("competence", competence))).list();
		
		List<Person> people = new ArrayList<Person>();
		for (Profile p : profiles) {
			people.add(p.getPerson());
		}
		return people;
	}   

pretty straighforward was my thought, but this Criteria causes the following exception:

org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: ... .models.Person