GH-839 - Check for a read only query hint.

Allow custom queries to indicate with `/*+ OGM READ_ONLY */` that they are read only. This will allow procedure calls to not flush the session and fix #839.
neo4j · Sep 10, 2020 · 6385a97 · 6385a97
1 parent 41702d5
commit 6385a97
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Showing 2 changed files with 30 additions and 1 deletion.
diff --git a/core/src/main/java/org/neo4j/ogm/session/delegates/ExecuteQueriesDelegate.java b/core/src/main/java/org/neo4j/ogm/session/delegates/ExecuteQueriesDelegate.java
@@ -71,6 +71,7 @@
  */
 public class ExecuteQueriesDelegate extends SessionDelegate {
 
+    private static final String OGM_READ_ONLY_HINT = "/*+ OGM READ_ONLY */";
     private static final Pattern WRITE_CYPHER_KEYWORDS = Pattern.compile("\\b(CREATE|MERGE|SET|DELETE|REMOVE|DROP|CALL)\\b",
         Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
     private static final Set<Class<?>> VOID_TYPES = new HashSet<>(Arrays.asList(Void.class, void.class));
@@ -159,7 +160,7 @@ private <T> Iterable<T> executeAndMap(Class<T> type, String cypher, Map<String,
 
             // While an update query may not return objects, it has enough changes
             // to modify all entities in the context, so we must flush it either way.
-            if (mayBeReadWrite(cypher)) {
+            if (mayBeReadWrite(cypher) && !cypher.contains(OGM_READ_ONLY_HINT)) {
                 session.clear();
             }
 

diff --git a/...tests/src/test/java/org/neo4j/ogm/persistence/session/capability/QueryCapabilityTest.java b/...tests/src/test/java/org/neo4j/ogm/persistence/session/capability/QueryCapabilityTest.java
@@ -25,6 +25,7 @@
 import ch.qos.logback.classic.LoggerContext;
 
 import java.io.IOException;
+import java.lang.reflect.Field;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -39,6 +40,8 @@
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.mockito.Mockito;
+import org.neo4j.ogm.context.MappingContext;
 import org.neo4j.ogm.domain.cineasts.annotated.Actor;
 import org.neo4j.ogm.domain.cineasts.annotated.ExtendedUser;
 import org.neo4j.ogm.domain.cineasts.annotated.Movie;
@@ -149,6 +152,31 @@ && isBoltDriver()) { // 4.1+ will fail on any attempt to write in a read-only tr
         }
     }
 
+    @Test
+    public void shouldBeAbleToIndicateSafeCall() throws NoSuchFieldException, IllegalAccessException {
+
+        // Don' think too long about that bloody mess…
+        MappingContext spyOnMappingContext = Mockito.spy(((Neo4jSession) session).context());
+        Field mappingContextField = Neo4jSession.class.getDeclaredField("mappingContext");
+        mappingContextField.setAccessible(true);
+        mappingContextField.set(session, spyOnMappingContext);
+
+        Iterable<String> functionNames = session
+            .query(String.class, "CALL dbms.functions() yield name", Collections.emptyMap());
+        assertThat(functionNames).isNotEmpty();
+        functionNames = session
+            .query(String.class, "CALL dbms.functions() yield name /*+ OGM READ_ONLY */", Collections.emptyMap());
+        assertThat(functionNames).isNotEmpty();
+        functionNames = session
+            .query(String.class, "CALL dbms.functions() yield name \n/*+ OGM READ_ONLY */", Collections.emptyMap());
+        assertThat(functionNames).isNotEmpty();
+        functionNames = session
+            .query(String.class, "CALL /*+ OGM READ_ONLY */ dbms.functions() yield name", Collections.emptyMap());
+        assertThat(functionNames).isNotEmpty();
+
+        Mockito.verify(spyOnMappingContext, Mockito.atMost(1)).clear();
+    }
+
     @Test // DATAGRAPH-697
     public void modifyingQueryShouldReturnStatistics() {
         session.save(new Actor("Jeff"));