Class Expressions

java.lang.Object

org.springframework.data.jpa.criteria.Expressions

public abstract class Expressions
extends Object

Utility methods to resolve JPA Criteria API objects using Spring Data's type-safe property references. These helper methods obtain Criteria API objects using TypedPropertyPath and PropertyReference to resolve property expressions and joins.

The class is intended for concise, type-aware criteria construction through a type-safe DSL where property references are preferred over string-based navigation.

Example:

Root<User> root = criteriaQuery.from(User.class);

Expression<User> expr = Expressions.get(root, User::getManager);

Join<User, Address> join = Expressions.join(root, JoinType.INNER, j -> j.join(User::getAddress));

Since:

4.1

Author:

Mark Paluch

See Also:

• PropertyReference
• TypedPropertyPath

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	Expressions.Fetcher<T>	Strategy interface used by fetch(From, PropertyReference) to obtain fetch joins using property references.
static interface	Expressions.Joiner<T>	Strategy interface used by join(From, PropertyReference) to obtain joins using property references.

Method Summary

Modifier and Type	Method	Description
static <T, F extends Fetch<?,?>> F	fetch(From<?,T> from, JoinType joinType, Function<Expressions.Fetcher<T>, F> function)	Create a fetch join considering JoinType using the given fetcher function allowing to express fetches using property references.
static <T,P> Fetch<T,P>	fetch(From<?,T> from, PropertyReference<T,P> property)	Create a fetch join using the given property.
static <T,P> Expression<P>	get(From<?,T> from, TypedPropertyPath<T,P> property)	Resolve an Expression for the given property path.
static <T, J extends Join<?,?>> J	join(From<?,T> from, JoinType joinType, Function<Expressions.Joiner<T>, J> function)	Create a Join considering JoinType using the given joiner function allowing to express joins using property references.
static <T,P> Join<T,P>	join(From<?,T> from, PropertyReference<T,P> property)	Create a Join using the given property.
static <T,P> Path<P>	path(Path<T> from, TypedPropertyPath<T,P> property)	Resolve a Path for the given property path.
static <T> List<Selection<?>>	select(From<?,T> from, TypedPropertyPath<T,?>... properties)	Create a list of selection objects for the given property paths.
static <T,P> Selection<P>	select(From<?,T> from, TypedPropertyPath<T,P> property)	Create a Selection for the given property path.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

path

public static <T,P> Path<P> path(Path<T> from,
 TypedPropertyPath<T,P> property)

Resolve a Path for the given property path.

The resulting path can be used in predicates. In case of a From path, Expression resolution navigates joins as necessary.

Parameters:

from - the entity or attribute path start from.

property - property path to navigate.

Returns:

the resolved path.

get

public static <T,P> Expression<P> get(From<?,T> from,
 TypedPropertyPath<T,P> property)

Resolve an Expression for the given property path.

The resulting expression can be used in predicates. Expression resolution navigates joins as necessary.

Parameters:

from - the root or join to start from.

property - property path to navigate.

Returns:

the resolved expression.

select

public static <T,P> Selection<P> select(From<?,T> from,
 TypedPropertyPath<T,P> property)

Create a Selection for the given property path.

The resulting object can be used in the selection, joined paths consider outer joins as needed.

Parameters:

from - the root or join to start from.

property - property path to navigate.

Returns:

the selection.

select

@SafeVarargs
public static <T> List<Selection<?>> select(From<?,T> from,
 TypedPropertyPath<T,?>... properties)

Create a list of selection objects for the given property paths.

The resulting objects can be used in the selection, joined paths consider outer joins as needed.

Parameters:

from - the root or join to start from.

properties - property path to navigate.

Returns:

the selection.

join

public static <T,P> Join<T,P> join(From<?,T> from,
 PropertyReference<T,P> property)

Create a Join using the given property.

Parameters:

from - the root or join to start from.

property - property reference to navigate.

Returns:

the resolved join.

See Also:

• From.join(String)

join

public static <T, J extends Join<?,?>> J join(From<?,T> from,
 JoinType joinType,
 Function<Expressions.Joiner<T>, J> function)

Create a Join considering JoinType using the given joiner function allowing to express joins using property references.

Parameters:

from - the root or join to start from.

joinType - the join type.

function - joiner function.

Returns:

the resolved join.

See Also:

• From.join(String, JoinType)

fetch

public static <T,P> Fetch<T,P> fetch(From<?,T> from,
 PropertyReference<T,P> property)

Create a fetch join using the given property.

Parameters:

from - the root or join to start from.

property - property reference to navigate.

Returns:

the resolved fetch.

See Also:

• FetchParent.fetch(String)

fetch

public static <T, F extends Fetch<?,?>> F fetch(From<?,T> from,
 JoinType joinType,
 Function<Expressions.Fetcher<T>, F> function)

Create a fetch join considering JoinType using the given fetcher function allowing to express fetches using property references.

Parameters:

from - the root or join to start from.

joinType - the join type.

function - fetcher function.

Returns:

the resolved fetch.

See Also:

• FetchParent.fetch(String, JoinType)