ruthst00 commented on code in PR #16573:
URL: https://github.com/apache/grails-core/pull/16573#discussion_r4415131059
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grails-data-hibernate7/core/src/main/groovy/org/grails/orm/hibernate/query/PredicateGenerator.java:
##########
@@ -306,20 +305,11 @@ private Predicate handleAssociationCriteria(
JpaQueryContext fromsByProvider,
DetachedAssociationCriteria<?> associationCriteria) {
String associationName = associationCriteria.getAssociationPath();
- From<?, ?> associationRoot = fromsByProvider.getFrom(associationName);
- if (associationRoot == null) {
- // Check if we already have it in our parent or alias map
- Expression<?> expr =
fromsByProvider.getFullyQualifiedExpression(associationName);
- if (expr instanceof From<?, ?> from) {
- associationRoot = from;
- } else {
- associationRoot =
fromsByProvider.getRoot().join(associationName);
- fromsByProvider.addFrom(associationName, associationRoot);
- }
- }
+ From<?, ?> associationRoot =
fromsByProvider.resolveAssociation(associationName);
// Create a nested context for this association
- JpaQueryContext nestedContext = new JpaQueryContext(fromsByProvider,
null, associationRoot);
+ JpaQueryContext nestedContext = new
QueryAliasRegistrar(associationCriteria, null)
+ .createContext(fromsByProvider, associationRoot);
Review Comment:
Fixed in
https://github.com/apache/grails-core/pull/16573/changes/ece3fd3d52a7b914a0cbf598d476e8b877312ac4
##########
grails-doc/src/en/ref/Domain Classes/createCriteria.adoc:
##########
@@ -75,10 +75,42 @@ The `sort` and `order` arguments accepted alongside the
pagination values are ch
=== Description
+Criteria queries are a type-safe, advanced way to query that uses a Groovy
builder to construct potentially complex queries. It is a much better
alternative to using a StringBuilder to dynamically construct an HQL query.
Refer to the criteria sections in the GORM for
link:{hibernate7GuideFromRef}index.html#criteria[Hibernate 7] or
link:{hibernate5GuideFromRef}index.html#criteria[Hibernate 5] guide for usage
instructions.
-Criteria queries are a type-safe, advanced way to query that uses a Groovy
builder to construct potentially complex queries. It is a much better
alternative to using a StringBuilder to dynamically construct an HQL query.
Refer to the user guide section on
link:{hibernate5GuideFromRef}index.html#criteria[Criteria] for usage
instructions.
+==== Association aliases
-Method reference:
+With Hibernate, `createAlias('association', 'alias')` creates an inner join
and lets you refer to the association as `alias.property`.
+
+In both Hibernate 5 and Hibernate 7, the three-argument overload accepts `0`
for an inner join, `1` for a left outer join, or `2` for a right outer join.
Hibernate 5 also supports `4` for a full join. Hibernate 7 does not support
full joins through this overload: any value other than `1` or `2`, including
`4`, produces an inner join.
+
+For example, to include books with no author as well as books whose author has
a name:
+
+[source,groovy]
+----
+def books = Book.createCriteria().list {
+ createAlias('author', 'a', 1) // left outer join
+ or {
+ isNull('author')
+ isNotNull('a.name')
+ }
+}
+----
+
+The alias uses the requested join type. A left join alone does not guarantee
that unmatched rows remain in the result: the restrictions must also allow the
missing association, as the `or` block does above.
+
+In Hibernate 7, every explicitly requested alias of an entity association
creates a join even when no restriction, projection, or order references it.
Declaring a left alias and an inner alias for the same association therefore
excludes rows with no associated entity, even if the inner alias is otherwise
unused.
+
+An alias declared inside an association block is relative to that association,
not the outer domain class. In Hibernate 7, aliases declared in a `list { ...
}` closure do not carry over to a subsequent `list { ... }` call on the same
criteria builder.
Review Comment:
Fixed in
https://github.com/apache/grails-core/pull/16573/changes/ece3fd3d52a7b914a0cbf598d476e8b877312ac4
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