JPA Criteria API with multiple parameters

Question

I need to make a search method that uses the JPA Criteria API with multiple parameters. Now the problem is that not every parameter is required. So some could be null, and t

Answer 1

A simple solution for Spring, using lambda expressions:

Specification<User> specification = (root, query, builder) -> {
    List<Predicate> predicates = new ArrayList<>();

    // like
    predicates.add(builder.like(root.get("name"), "%test%"));

    // equal
    predicates.add(builder.equal(root.get("parent_id"), 99L);


    // AND all predicates
    return builder.and(predicates.toArray(new Predicate[0]));
};

repository.findAll(specification);

Answer 2

Mikko's answer worked beautifully. Only change I needed to do, was to replace:

cq.select(customer).where(predicates.toArray(new Predicate[]{}));

with:

Predicate [] predicatesarr = predicates.toArray(new Predicate[predicates.size()]); 
cq.select(customer).where(predicatesarr);

Somewhere the conversion from list to array in the original did not work.

Answer 3

Take a look at this site JPA Criteria API. There are plenty of examples.

Update: Providing a concrete example

Let's search for Accounts with a balance lower than a specific value:

SELECT a FROM Account a WHERE a.balance < :value

First create a Criteria Builder

CriteriaBuilder builder = entityManager.getCriteriaBuilder();

CriteriaQuery<Account> accountQuery = builder.createQuery(Account.class);
Root<Account> accountRoot = accountQuery.from(Account.class);
ParameterExpression<Double> value = builder.parameter(Double.class);
accountQuery.select(accountRoot).where(builder.lt(accountRoot.get("balance"), value));

To get the result set the parameter(s) and run the query:

TypedQuery<Account> query = entityManager.createQuery(accountQuery);
query.setParameter(value, 1234.5);
List<Account> results = query.getResultList();

BTW: The entityManager is injected somewhere in an EJB/Service/DAO.

Answer 4

First, Mikko's answer got me to my answer. Upvote for that.

My scenario was I wanted to parent/child relationship and I wanted to find a match on ~any~ child.

Employee has multiple JobTitle(s).

I wanted to find an employee (where the has many job titles), but find it on ~any of the jobtitles I send in.

SQL would look like:

Select * from dbo.Employee e join dbo.JobTitle jt on e.EmployeeKey = jt.EmployeeKey WHERE ( jt.JobTitleName = 'programmer' OR jt.JobTitleName = 'badcop' )

I threw in gender and date-of-birth to complete the example (and give more "optional") criteria)

My JPA code

import org.apache.commons.lang3.StringUtils;
import org.springframework.data.jpa.domain.Specification;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Join;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.ArrayList;
import java.util.List;

public class MyEmployeeSpecification implements Specification<MyEmployee> {

    private MyEmployee filter;

    public MyEmployeeSpecification(MyEmployee filter) {
        super();
        this.filter = filter;
    }

    public Predicate toPredicate(Root<MyEmployee> root, CriteriaQuery<?> cq,
                                 CriteriaBuilder cb) {

        Predicate returnPred = cb.disjunction();

        List<Predicate> patientLevelPredicates = new ArrayList<Predicate>();

        if (filter.getBirthDate() != null) {
            patientLevelPredicates.add(
                    cb.equal(root.get("birthDate"), filter.getBirthDate()));
        }

        if (filter.getBirthDate() != null) {
            patientLevelPredicates.add(
                    cb.equal(root.get("gender"), filter.getGender()));
        }

        if (null != filter.getJobTitles() && filter.getJobTitles().size() > 0) {

            List<Predicate> jobTitleLevelPredicates = new ArrayList<Predicate>();

            Join<JobTitle, JobTitle> hnJoin = root.join("jobtitles");

            for (JobTitle hnw : filter.getJobTitles()) {
                if (null != hnw) {
                    if (StringUtils.isNotBlank(hnw.getJobTitleName())) {
                        jobTitleLevelPredicates.add(cb.equal(hnJoin.get("getJobTitleName"), hnw.getFamily()));
                    }
                }
            }

            patientLevelPredicates.add(cb.or(jobTitleLevelPredicates.toArray(new Predicate[]{})));
        }

        returnPred = cb.and(patientLevelPredicates.toArray(new Predicate[]{}));

        return returnPred;
    }
}

But I figured mine out because of predicates.toArray(new Predicate[]{}) , aka, the varargs trick. (Thanks Mikko)

I'm also doing the "implements Specifiction" method.

Other helpful links:

JPA Specifications by Example

JPA CriteriaBuilder conjunction criteria into a disjunction criteria

Answer 5

Concept is to construct array of javax.persistence.Predicate which contains only predicates we want to use:

Example entity to be queried:

@Entity
public class A {
    @Id private Long id;    
    String someAttribute;
    String someOtherAttribute;
    ...
}

Query itself:

    //some parameters to your method
    String param1 = "1";
    String paramNull = null;

    CriteriaBuilder qb = em.getCriteriaBuilder();
    CriteriaQuery cq = qb.createQuery();
    Root<A> customer = cq.from(A.class);

    //Constructing list of parameters
    List<Predicate> predicates = new ArrayList<Predicate>();

    //Adding predicates in case of parameter not being null
    if (param1 != null) {
        predicates.add(
                qb.equal(customer.get("someAttribute"), param1));
    }
    if (paramNull != null) {
        predicates.add(
                qb.equal(customer.get("someOtherAttribute"), paramNull));
    }
    //query itself
    cq.select(customer)
            .where(predicates.toArray(new Predicate[]{}));
    //execute query and do something with result
    em.createQuery(cq).getResultList();