Can we build Spring Data JPA specification out of a composite key attribute - spring

Question

I am using Spring Data JPA specifications for generic queries to my entities. So far it has worked well. Now the problem happened when I try to use these on composite keys used via embeddedId annotation. So here I need to use a nested property to query which say if the object is Foo and I am trying to write a criteria over id. id1 for example.
#Entity
#Data
public class Foo implements Serializable {
private static final long serialVersionUID = 1L;
/** The key. */
#EmbeddedId
private FooKey id;
}
#Embeddable
#Data
public class FooKey implements Serializable {
private static final long serialVersionUID = 1L;
/** The key. */
private String id1;
private String id2;
}
In the specification I am trying to do
#Override
public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
// get root type
root.get(property).getJavaType()
But this doesn't work for nested attributes like in this case. Is there any way I can be able to build predicates for properties in the composite key.

Answer 1

Example of Equal:
#Override
public Predicate toPredicate(Root<Foo> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
builder.equal(root.get("id").get("id1"),"my val");

Answer 2

You can build a function like this if you want to use multiple levels. In my experience, 2 levels are more than sufficient. But depends on you.
protected Path<Comparable> getPath(Root<EntityOrModel> root) {
Path<Comparable> path;
if (criteria.getKey().contains(".")) {
String[] split = criteria.getKey().split("\\.");
int keyPosition = 0;
path = root.get(split[keyPosition]);
for (String criteriaKeys : split) {
if (keyPosition > 0) {
path = path.get(criteriaKeys);
}
keyPosition++;
}
} else {
path = root.get(criteria.getKey());
}
return path;
}
Then set
#Override
public Predicate toPredicate(Root<EntityOrModel> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
Path<Comparable> path = getPath(root);
// ...
return builder.equal(path, value)
}