JPA Criteria API Queries

The JPA Criteria API provides an alternative way for defining JPA queries, which is mainly useful for building dynamic queries whose exact structure is only known at runtime.

JPA Criteria API vs JPQL

JPQL queries are defined as strings, similarly to SQL. JPA criteria queries, on the other hand, are defined by the instantiation of Java objects that represent query elements.

A major advantage of using the criteria API is that errors can be detected earlier, during compilation rather than at runtime. On the other hand, for many developers string based JPQL queries, which are very similar to SQL queries, are easier to use and understand.

For simple static queries - string based JPQL queries (e.g. as named queries) may be preferred. For dynamic queries that are built at runtime - the criteria API may be preferred.

For example, building a dynamic query based on fields that a user fills at runtime in a form that contains many optional fields - is expected to be cleaner when using the JPA criteria API, because it eliminates the need for building the query using many string concatenation operations.

String based JPQL queries and JPA criteria based queries are equally powerful and efficient. Therefore, choosing one method over the other is also a matter of personal preference. 

First JPA Criteria Query

The following query string represents a minimal JPQL query:

SELECT c FROM Country c

An equivalent query can be built using the JPA criteria API as follows:

  CriteriaBuilderjavax.persistence.criteria.CriteriaBuilder - JPA InterfaceUsed to construct criteria queries, compound selections,
 expressions, predicates, orderings. cb = em.getCriteriaBuilderEntityManager.getCriteriaBuilder() - JPA MethodReturn an instance of CriteriaBuilder for the creation of
 CriteriaQuery objects.();

  CriteriaQueryjavax.persistence.criteria.CriteriaQuery - JPA InterfaceThe CriteriaQuery interface defines functionality that is specific
 to top-level queries.<Country> q = cb.createQueryCriteriaBuilder.createQuery(resultClass) - JPA MethodCreate a CriteriaQuery object with the specified result
  type.(Country.class);
  Rootjavax.persistence.criteria.Root - JPA InterfaceA root type in the from clause.<Country> c = q.fromAbstractQuery.from(entityClass) - JPA MethodCreate and add a query root corresponding to the given entity,
 forming a cartesian product with any existing roots.(Country.class);
  q.selectCriteriaQuery.select(selection) - JPA MethodSpecify the item that is to be returned in the query result.(c);

The CriteriaBuilderjavax.persistence.criteria.CriteriaBuilder - JPA InterfaceUsed to construct criteria queries, compound selections, expressions, predicates, orderings. interface serves as the main factory of criteria queries and criteria query elements. It can be obtained either by the EntityManagerFactoryjavax.persistence.EntityManagerFactory - JPA InterfaceInterface used to interact with the entity manager factory for the persistence unit.'s getCriteriaBuilderEntityManagerFactory.getCriteriaBuilder() - JPA MethodReturn an instance of CriteriaBuilder for the creation of CriteriaQuery objects. method or by the EntityManagerjavax.persistence.EntityManager - JPA InterfaceInterface used to interact with the persistence context.'s getCriteriaBuilderEntityManager.getCriteriaBuilder() - JPA MethodReturn an instance of CriteriaBuilder for the creation of CriteriaQuery objects. method (both methods are equivalent).

In the example above a CriteriaQueryjavax.persistence.criteria.CriteriaQuery - JPA InterfaceThe CriteriaQuery interface defines functionality that is specific to top-level queries. instance is created for representing the built query. Then a Rootjavax.persistence.criteria.Root - JPA InterfaceA root type in the from clause. instance is created to define a range variable in the FROM clause. Finally, the range variable, c, is also used in the SELECT clause as the query result expression.

A CriteriaQuery instance is equivalent to a JPQL string and not to a TypedQueryjavax.persistence.TypedQuery - JPA InterfaceInterface used to control the execution of typed queries. instance. Therefore, running the query still requires a TypedQuery instance:

  TypedQueryjavax.persistence.TypedQuery - JPA InterfaceInterface used to control the execution of typed queries.<Country> query = em.createQueryEntityManager.createQuery(criteriaQuery) - JPA MethodCreate an instance of TypedQuery for executing a
 criteria query.(q);
  List<Country> results = query.getResultListQuery.getResultList() - JPA MethodExecute a SELECT query and return the query results
 as an untyped List.();

Using the criteria API introduces some extra work, at least for simple static queries, since the equivalent JPQL query could simply be executed as follows:

  TypedQueryjavax.persistence.TypedQuery - JPA InterfaceInterface used to control the execution of typed queries.<Country> query =
      em.createQueryEntityManager.createQuery(qlString,resultClass) - JPA MethodCreate an instance of TypedQuery for executing a
 Java Persistence query language statement.("SELECT c FROM Country c", Country.class);
  List<Country> results = query.getResultListQuery.getResultList() - JPA MethodExecute a SELECT query and return the query results
 as an untyped List.();

Because eventually both types of queries are represented by a TypedQueryjavax.persistence.TypedQuery - JPA InterfaceInterface used to control the execution of typed queries. instance - query execution and query setting is similar, regardless of the way in which the query is built.

Parameters in Criteria Queries

The following query string represents a JPQL query with a parameter:

SELECT c FROM Country c WHERE c.population > :p

An equivalent query can be built using the JPA criteria API as follows:

  CriteriaBuilderjavax.persistence.criteria.CriteriaBuilder - JPA InterfaceUsed to construct criteria queries, compound selections,
 expressions, predicates, orderings. cb = em.getCriteriaBuilderEntityManager.getCriteriaBuilder() - JPA MethodReturn an instance of CriteriaBuilder for the creation of
 CriteriaQuery objects.();

  CriteriaQueryjavax.persistence.criteria.CriteriaQuery - JPA InterfaceThe CriteriaQuery interface defines functionality that is specific
 to top-level queries.<Country> q = cb.createQueryCriteriaBuilder.createQuery(resultClass) - JPA MethodCreate a CriteriaQuery object with the specified result
  type.(Country.class);
  Rootjavax.persistence.criteria.Root - JPA InterfaceA root type in the from clause.<Country> c = q.fromAbstractQuery.from(entityClass) - JPA MethodCreate and add a query root corresponding to the given entity,
 forming a cartesian product with any existing roots.(Country.class);
  ParameterExpressionjavax.persistence.criteria.ParameterExpression - JPA InterfaceType of criteria query parameter expressions.<Integer> p = cb.parameterCriteriaBuilder.parameter(paramClass) - JPA MethodCreate a parameter expression.(Integer.class);
  q.selectCriteriaQuery.select(selection) - JPA MethodSpecify the item that is to be returned in the query result.(c).whereCriteriaQuery.where(restriction) - JPA MethodModify the query to restrict the query result according
 to the specified boolean expression.(cb.gtCriteriaBuilder.gt(x,y) - JPA MethodCreate a predicate for testing whether the first argument is
 greater than the second.(c.getPath.get(attributeName) - JPA MethodCreate a path corresponding to the referenced attribute.("population"), p));

The ParameterExpressionjavax.persistence.criteria.ParameterExpression - JPA InterfaceType of criteria query parameter expressions. instance, p, is created to represent the query parameter. The whereCriteriaQuery.where(restriction) - JPA MethodModify the query to restrict the query result according to the specified boolean expression. method sets the WHERE clause. As shown above, The CriteriaQueryjavax.persistence.criteria.CriteriaQuery - JPA InterfaceThe CriteriaQuery interface defines functionality that is specific to top-level queries. interface supports method chaining. See the links in the next sections of this page for detailed explanations on how to set criteria query clauses and build criteria expressions.

Running this query requires setting the parameter:

  TypedQueryjavax.persistence.TypedQuery - JPA InterfaceInterface used to control the execution of typed queries.<Country> query = em.createQueryEntityManager.createQuery(criteriaQuery) - JPA MethodCreate an instance of TypedQuery for executing a
 criteria query.(q);
  query.setParameterQuery.setParameter(param,value) - JPA MethodBind the value of a Parameter object.(p, 10000000);
  List<Country> results = query.getResultListQuery.getResultList() - JPA MethodExecute a SELECT query and return the query results
 as an untyped List.();

The setParameterQuery.setParameter(param,value) - JPA MethodBind the value of a Parameter object. method takes a Parameterjavax.persistence.Parameter - JPA InterfaceType for query parameter objects. (or a ParameterExpressionjavax.persistence.criteria.ParameterExpression - JPA InterfaceType of criteria query parameter expressions.) instance as the first argument instead of a name or a position (which are used with string based JPQL parameters).

Criteria Query Structure

Queries in JPA (as in SQL) are composed of clauses. Because JPQL queries and criteria queries use equivalent clauses - they are explained side by side in the Query Structure pages.

Specific details about criteria query clauses are provided in the following page sections:

• SELECT clause (selectCriteriaQuery.select(selection) - JPA MethodSpecify the item that is to be returned in the query result., distinctCriteriaQuery.distinct(distinct) - JPA MethodSpecify whether duplicate query results will be eliminated., multiselectCriteriaQuery.multiselect(selections) - JPA MethodSpecify the selection items that are to be returned in the query result., arrayCriteriaBuilder.array(selections) - JPA MethodCreate an array-valued selection item., tupleCriteriaBuilder.tuple(selections) - JPA MethodCreate a tuple-valued selection item., constructCriteriaBuilder.construct(resultClass,selections) - JPA MethodCreate a selection item corresponding to a constructor.).
• FROM clause (fromAbstractQuery.from(entityClass) - JPA MethodCreate and add a query root corresponding to the given entity, forming a cartesian product with any existing roots., joinFrom.join(attributeName,jt) - JPA MethodCreate a join to the specified attribute using the given join type., fetchFetchParent.fetch(attributeName) - JPA MethodCreate a fetch join to the specified attribute using an inner join.).
• WHERE clause (whereCriteriaQuery.where(restrictions) - JPA MethodModify the query to restrict the query result according to the conjunction of the specified restriction predicates.).
• GROUP BY / HAVING clauses (groupByCriteriaQuery.groupBy(grouping) - JPA MethodSpecify the expressions that are used to form groups over the query results., havingCriteriaQuery.having(restriction) - JPA MethodSpecify a restriction over the groups of the query., countCriteriaBuilder.count(x) - JPA MethodCreate an aggregate expression applying the count operation., sumCriteriaBuilder.sum(x) - JPA MethodCreate an aggregate expression applying the sum operation., avgCriteriaBuilder.avg(x) - JPA MethodCreate an aggregate expression applying the avg operation., minCriteriaBuilder.min(x) - JPA MethodCreate an aggregate expression applying the numerical min operation., maxCriteriaBuilder.max(x) - JPA MethodCreate an aggregate expression applying the numerical max operation., ...).
• ORDER BY clause (orderByCriteriaQuery.orderBy(o) - JPA MethodSpecify the ordering expressions that are used to order the query results., Orderjavax.persistence.criteria.Order - JPA InterfaceAn object that defines an ordering over the query results., ascCriteriaBuilder.asc(x) - JPA MethodCreate an ordering by the ascending value of the expression., descCriteriaBuilder.desc(x) - JPA MethodCreate an ordering by the descending value of the expression.).

The links above are direct links to the criteria query sections in pages that describe query structure in general, including in the context of string based JPQL queries.

Criteria Query Expressions

JPA query clauses are composed of expressions. Because JPQL queries and criteria queries use equivalent expressions - they are explained side by side in the Query Expressions pages.

Specific details about criteria query expressions are provided in the following page sections:

• Literals and Dates (literalCriteriaBuilder.literal(value) - JPA MethodCreate an expression for a literal., nullLiteralCriteriaBuilder.nullLiteral(resultClass) - JPA MethodCreate an expression for a null literal with the given type., currentDateCriteriaBuilder.currentDate() - JPA MethodCreate expression to return current date., ...).
• Paths, navigation and types (getPath.get(attributeName) - JPA MethodCreate a path corresponding to the referenced attribute., typePath.type() - JPA MethodCreate an expression corresponding to the type of the path.).
• Arithmetic expressions (sumCriteriaBuilder.sum(x,y) - JPA MethodCreate an expression that returns the sum of its arguments., diffCriteriaBuilder.diff(x,y) - JPA MethodCreate an expression that returns the difference between its arguments., prodCriteriaBuilder.prod(x,y) - JPA MethodCreate an expression that returns the product of its arguments., quotCriteriaBuilder.quot(x,y) - JPA MethodCreate an expression that returns the quotient of its arguments., modCriteriaBuilder.mod(x,y) - JPA MethodCreate an expression that returns the modulus of its arguments., absCriteriaBuilder.abs(x) - JPA MethodCreate an expression that returns the absolute value of its argument., negCriteriaBuilder.neg(x) - JPA MethodCreate an expression that returns the arithmetic negation of its argument., sqrtCriteriaBuilder.sqrt(x) - JPA MethodCreate an expression that returns the square root of its argument.).
• String expressions (likeCriteriaBuilder.like(x,pattern) - JPA MethodCreate a predicate for testing whether the expression satisfies the given pattern., lengthCriteriaBuilder.length(x) - JPA MethodCreate expression to return length of a string., locateCriteriaBuilder.locate(x,pattern) - JPA MethodCreate expression to locate the position of one string within another, returning position of first character if found., lowerCriteriaBuilder.lower(x) - JPA MethodCreate expression for converting a string to lowercase., upperCriteriaBuilder.upper(x) - JPA MethodCreate expression for converting a string to uppercase., concatCriteriaBuilder.concat(x,y) - JPA MethodCreate an expression for string concatenation., substringCriteriaBuilder.substring(x,from) - JPA MethodCreate an expression for substring extraction., ...).
• Collection expressions (isEmptyCriteriaBuilder.isEmpty(collection) - JPA MethodCreate a predicate that tests whether a collection is empty., isNotEmptyCriteriaBuilder.isNotEmpty(collection) - JPA MethodCreate a predicate that tests whether a collection is not empty., isMemberCriteriaBuilder.isMember(elem,collection) - JPA MethodCreate a predicate that tests whether an element is a member of a collection., isNotMemberCriteriaBuilder.isNotMember(elem,collection) - JPA MethodCreate a predicate that tests whether an element is not a member of a collection., sizeCriteriaBuilder.size(collection) - JPA MethodCreate an expression that tests the size of a collection.).
• Comparison expressions (equalCriteriaBuilder.size(collection) - JPA MethodCreate an expression that tests the size of a collection., notEqualCriteriaBuilder.notEqual(x,y) - JPA MethodCreate a predicate for testing the arguments for inequality., gtCriteriaBuilder.gt(x,y) - JPA MethodCreate a predicate for testing whether the first argument is greater than the second., geCriteriaBuilder.ge(x,y) - JPA MethodCreate a predicate for testing whether the first argument is greater than or equal to the second., ltCriteriaBuilder.lt(x,y) - JPA MethodCreate a predicate for testing whether the first argument is less than the second., leCriteriaBuilder.le(x,y) - JPA MethodCreate a predicate for testing whether the first argument is less than or equal to the second., betweenCriteriaBuilder.between(v,x,y) - JPA MethodCreate a predicate for testing whether the first argument is between the second and third arguments in value., isNullCriteriaBuilder.isNull(x) - JPA MethodCreate a predicate to test whether the expression is null., ...)
• Logical expressions (andCriteriaBuilder.and(x,y) - JPA MethodCreate a conjunction of the given boolean expressions., orCriteriaBuilder.or(x,y) - JPA MethodCreate a disjunction of the given boolean expressions., notCriteriaBuilder.not(restriction) - JPA MethodCreate a negation of the given restriction., isTrueCriteriaBuilder.isTrue(x) - JPA MethodCreate a predicate testing for a true value.).

The links above are direct links to the criteria query sections in pages that describe expressions in general, including in the context of string based JPQL queries.