fix: properly compute search panes with related entities

Related: #159

Author: darrachequesne

src/main/java/org/springframework/data/jpa/datatables/repository/DataTablesRepositoryImpl.java

@@ -3,11 +3,9 @@
 import jakarta.persistence.EntityManager;
 import jakarta.persistence.criteria.CriteriaBuilder;
 import jakarta.persistence.criteria.CriteriaQuery;
+import jakarta.persistence.criteria.Path;
 import jakarta.persistence.criteria.Root;
 import lombok.extern.slf4j.Slf4j;
-import org.hibernate.query.sqm.tree.domain.AbstractSqmFrom;
-import org.hibernate.query.sqm.tree.domain.SqmPath;
-import org.hibernate.query.sqm.tree.from.SqmAttributeJoin;
 import org.springframework.data.domain.Page;
 import org.springframework.data.jpa.datatables.SpecificationBuilder;
 import org.springframework.data.jpa.datatables.mapping.DataTablesInput;
@@ -109,8 +107,10 @@ private SearchPanes computeSearchPanes(DataTablesInput input, Specification<T> s
       CriteriaBuilder criteriaBuilder = this.entityManager.getCriteriaBuilder();
       CriteriaQuery<Object[]> query = criteriaBuilder.createQuery(Object[].class);
       Root<T> root = query.from(getDomainClass());
-      query.multiselect(root.get(attribute), criteriaBuilder.count(root));
-      query.groupBy(root.get(attribute));
+      Path<?> path = getPath(root, attribute);
+
+      query.multiselect(path, criteriaBuilder.count(root));
+      query.groupBy(path);
       query.where(specification.toPredicate(root, query, criteriaBuilder));
 
       List<SearchPanes.Item> items = new ArrayList<>();
@@ -127,4 +127,13 @@ private SearchPanes computeSearchPanes(DataTablesInput input, Specification<T> s
     return new SearchPanes(options);
   }
 
+  private Path<?> getPath(Root<T> root, String attribute) {
+    String[] parts = attribute.split("\\.");
+    Path<?> path = root;
+    for (String part : parts) {
+      path = path.get(part);
+    }
+    return path;
+  }
+
 }

src/test/java/org/springframework/data/jpa/datatables/repository/EmployeeRepositoryTest.java

@@ -318,13 +318,16 @@ void withSearchPanes() {
         Map<String, Set<String>> searchPanes = new HashMap<>();
         searchPanes.put("position", new HashSet<>(asList("Software Engineer", "Integration Specialist")));
         searchPanes.put("age", emptySet());
+        searchPanes.put("office.city", emptySet());
 
         input.setSearchPanes(searchPanes);
 
         DataTablesOutput<Employee> output = getOutput(input);
         assertThat(output.getRecordsFiltered()).isEqualTo(3);
         assertThat(output.getSearchPanes()).isNotNull();
 
+        assertThat(output.getSearchPanes().getOptions().size()).isEqualTo(3);
+
         assertThat(output.getSearchPanes().getOptions().get("position")).containsOnly(
                 new SearchPanes.Item("Software Engineer", "Software Engineer", 2, 2),
                 new SearchPanes.Item("Integration Specialist", "Integration Specialist", 1, 1)
@@ -334,6 +337,11 @@ void withSearchPanes() {
                 new SearchPanes.Item("41", "41", 1, 1),
                 new SearchPanes.Item("61", "61", 1, 1)
         );
+        assertThat(output.getSearchPanes().getOptions().get("office.city")).containsOnly(
+                new SearchPanes.Item("London", "London", 1, 1),
+                new SearchPanes.Item("New York", "New York", 1, 1),
+                new SearchPanes.Item("San Francisco", "San Francisco", 1, 1)
+        );
     }
 
     @Test