Using TIMESTAMPDIFF with JPA criteria query and hibernate as the provider

Question

I have a data table with columns setup and release, both of which hold timestamps. My goal is to create an equivalent of the SQL query below using CriteriaQuery.

SQL Query:SELECT TIMESTAMPDIFF(SECOND, setup, released)) as sum_duration FROM calls

The CriteriaBuilder#diff() function clearly does not work as it requires parameters that are Numbers, so I tried using CriteriaBuilder#function:

EntityManager entityManager = emProvider.get();

CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();

CriteriaQuery<Integer> query = criteriaBuilder.createQuery();

Root<Thingy> thingyRoot = query.from(Thingy.class);

Path<DateTime> setup = root.get("setup");
Path<DateTime> release = root.get("release");

Expression secondLiteral = criteriaBuilder.literal("SECOND");

Expression func = criteriaBuilder.function("TIMESTAMPDIFF", Integer.class, secondLiteral, setup, release);

entityManager.createQuery(query).getResultList();

However, when I tried running this code it threw an exception; it appears that the literal was not rendered as a constant, but rather as a parameter:

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'TIMESTAMPDIFF' {originalText=TIMESTAMPDIFF}
    \-[EXPR_LIST] SqlNode: 'exprList'
       +-[NAMED_PARAM] ParameterNode: '?' {name=param0, expectedType=null}
       +-[DOT] DotNode: 'cdr0_.setup' {propertyName=setup,dereferenceType=ALL,propertyPath=setup,path=generatedAlias0.setup,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
       |  +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
       |  \-[IDENT] IdentNode: 'setup' {originalText=setup}
       \-[DOT] DotNode: 'cdr0_.release' {propertyName=release,dereferenceType=ALL,propertyPath=release,path=generatedAlias0.release,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
          +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
          \-[IDENT] IdentNode: 'release' {originalText=release}

So I tried anonymously overriding the LiteralExpression#render to directly return the string I supply to the method, however that thew this exception.

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'TIMESTAMPDIFF' {originalText=TIMESTAMPDIFF}
    \-[EXPR_LIST] SqlNode: 'exprList'
       +-[IDENT] IdentNode: 'SECOND' {originalText=SECOND}
       +-[DOT] DotNode: 'cdr0_.setup' {propertyName=setup,dereferenceType=ALL,propertyPath=setup,path=generatedAlias0.setup,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
       |  +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
       |  \-[IDENT] IdentNode: 'setup' {originalText=setup}
       \-[DOT] DotNode: 'cdr0_.release' {propertyName=release,dereferenceType=ALL,propertyPath=release,path=generatedAlias0.release,tableAlias=cdr0_,className=com.vtsl.domain.CDR,classAlias=generatedAlias0}
          +-[ALIAS_REF] IdentNode: 'cdr0_.id' {alias=generatedAlias0, className=com.vtsl.domain.CDR, tableAlias=cdr0_}
          \-[IDENT] IdentNode: 'release' {originalText=release}

So the question is: How can I either fix this operation I'm trying to do, or achieve the original goal?

I'm using Hibernate, my database is MySQL.

Answer 1

Here is explanation of equivalent JPA Criteria Query of

SELECT * from calls where TIMESTAMPDIFF(SECOND, setup, released) < 3600;

First you have to create unit expression and extend it from BasicFunctionExpression for which take "SECOND" parameter as a unit and override its rendor(RenderingContext renderingContext) method only.

import java.io.Serializable;
import org.hibernate.query.criteria.internal.CriteriaBuilderImpl;
import org.hibernate.query.criteria.internal.compile.RenderingContext;
import org.hibernate.query.criteria.internal.expression.function.BasicFunctionExpression;

public class UnitExpression extends BasicFunctionExpression<String> implements Serializable {

  public UnitExpression(CriteriaBuilderImpl criteriaBuilder, Class<String> javaType,
      String functionName) {
    super(criteriaBuilder, javaType, functionName);
  }

  @Override
  public String render(RenderingContext renderingContext) {
    return getFunctionName();
  }
}

then you use this unit expression in your JPA criteria Query.

EntityManager entityManager = emProvider.get();
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
Root<Calls> thingyRoot = query.from(Calls.class);

    Expression<String> second = new UnitExpression(null, String.class, "SECOND");
    Expression<Integer> timeInSec = cb.function(
        "TIMESTAMPDIFF",
        Integer.class,
        second ,
        root.<Timestamp>get("setup"),
        root.<Timestamp>get("release"));
    List<Predicate> conditions = new ArrayList<>();
    conditions.add(cb.lessThan(timeInSec, 3600));
    cq.where(conditions.toArray(new Predicate[]{}));
    return session.createQuery(cq);

It is working.

Answer 2

I bumped into the same problem: the SECOND will be surrounded by apostrophes and the query will throw an exception.

I worked around it by the following code:

CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<MyEntity> cq = builder.createQuery( MyEntity.class );
Root<MyEntity> root = cq.from( MyEntity.class );

javax.persistence.criteria.Expression<java.sql.Time> timeDiff = builder.function(
            "TIMEDIFF",
            java.sql.Time.class,
            root.<Date>get( "endDate" ),
            root.<Date>get( "startDate" ) );
javax.persistence.criteria.Expression<Integer> timeToSec = builder.function(
            "TIME_TO_SEC",
            Integer.class,
            timeDiff );

//lessThanOrEqualTo 60 minutes
cq.where( builder.lessThanOrEqualTo( timeToSec, 3600 ) );

return em.createQuery( cq ).getResultList();

And this gives me the same result.