support both, single command or list of commands for apoc.systemdb.execute (#1628)

* fixes 1627: support both, a single command or a list of commands for apoc.systemdb.execute

* don't commit once tx has failed

docs/asciidoc/modules/ROOT/pages/database-introspection/systemdb.adoc

@@ -2,8 +2,6 @@
 = SystemDB
 :description: This section describes procedures that can be used to access the contents of Neo4j system db.
 
-
-
 In Neo4j 4.0 the concept of multi-database was introduced. There's now a database called `system` which contains some
 internal information, e.g. configured permissions. Those can be exposed by APOC.
 
@@ -16,7 +14,7 @@ and might change within minor release updates.
 [cols="5m,5"]
 |===
 | apoc.systemdb.graph | returns a `nodes` and `relationships` stored in systemdb.
-| apoc.systemdb.execute | executes an DDL command on system db, yields `row` for further processing
+| apoc.systemdb.execute | executes an DDL command or a list of DDL commands on system db, yields `row` for further processing
 |===
 
 .isType example
@@ -24,4 +22,5 @@ and might change within minor release updates.
 ----
 CALL apoc.systemdb.graph() YIELD nodes, relationships RETURN *;
 CALL apoc.systemdb.execute('SHOW DATABASES') YIELD row RETURN row.name as dbName;
+CALL apoc.systemdb.execute(["CREATE USER foo", "GRANT ROLE myRole TO foo"])
 ----

full/src/main/java/apoc/systemdb/SystemDb.java

@@ -12,10 +12,12 @@ import org.neo4j.graphdb.Relationship;
 import org.neo4j.graphdb.Transaction;
 import org.neo4j.internal.helpers.collection.Iterables;
 import org.neo4j.internal.kernel.api.security.SecurityContext;
+import org.neo4j.kernel.impl.coreapi.TransactionImpl;
 import org.neo4j.procedure.Context;
 import org.neo4j.procedure.Name;
 import org.neo4j.procedure.Procedure;
 
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -28,7 +30,7 @@ public class SystemDb {
 
     @Context
     public ApocConfig apocConfig;
-    
+
     @Context
     public SecurityContext securityContext;
 
@@ -63,9 +65,26 @@ public class SystemDb {
     }
 
     @Procedure
-    public Stream<RowResult> execute(@Name("DDL command") String command, @Name(value="params", defaultValue = "{}") Map<String ,Object> params) {
+    public Stream<RowResult> execute(@Name("DDL commands, either a string or a list of strings") Object ddlStringOrList, @Name(value="params", defaultValue = "{}") Map<String ,Object> params) {
         Util.checkAdmin(securityContext,"apoc.systemdb.execute");
-        return withSystemDbTransaction(tx -> tx.execute(command, params).stream().map(map -> new RowResult(map)));
+
+        List<String> commands;
+        if (ddlStringOrList instanceof String) {
+            commands = Collections.singletonList((String)ddlStringOrList);
+        } else if (ddlStringOrList instanceof List) {
+            commands = (List<String>) ddlStringOrList;
+        } else {
+            throw new IllegalArgumentException("don't know how to handle " + ddlStringOrList + ". Supply either a string or a list of strings");
+        }
+
+        Transaction tx = apocConfig.getSystemDb().beginTx();  // we can't use try-with-resources otherwise tx gets closed too early
+        return commands.stream().flatMap(command -> tx.execute(command, params).stream().map(RowResult::new)).onClose(() -> {
+            boolean isOpen = ((TransactionImpl) tx).isOpen(); // no other way to check if a tx is still open
+            if (isOpen) {
+                tx.commit();
+            }
+            tx.close();
+        });
     }
 
     private <T> T withSystemDbTransaction(Function<Transaction, T> function) {

full/src/test/java/apoc/systemdb/SystemDbTest.java

@@ -19,7 +19,8 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.stream.Collectors;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 public class SystemDbTest {
 
@@ -39,11 +40,11 @@ public class SystemDbTest {
             List<Relationship> relationships = (List<Relationship>) map.get("relationships");
 
             assertEquals(4, nodes.size());
-            assertEquals( 2, nodes.stream().filter( node -> "Database".equals(Iterables.single(node.getLabels()).name())).count());
-            assertEquals( 1, nodes.stream().filter( node -> "User".equals(Iterables.single(node.getLabels()).name())).count());
-            assertEquals( 1, nodes.stream().filter( node -> "Version".equals(Iterables.single(node.getLabels()).name())).count());
-            Set<String> names = nodes.stream().map(node -> (String)node.getProperty("name")).filter(Objects::nonNull).collect(Collectors.toSet());
-            org.hamcrest.MatcherAssert.assertThat( names, Matchers.containsInAnyOrder("neo4j", "system"));
+            assertEquals(2, nodes.stream().filter(node -> "Database".equals(Iterables.single(node.getLabels()).name())).count());
+            assertEquals(1, nodes.stream().filter(node -> "User".equals(Iterables.single(node.getLabels()).name())).count());
+            assertEquals(1, nodes.stream().filter(node -> "Version".equals(Iterables.single(node.getLabels()).name())).count());
+            Set<String> names = nodes.stream().map(node -> (String) node.getProperty("name")).filter(Objects::nonNull).collect(Collectors.toSet());
+            org.hamcrest.MatcherAssert.assertThat(names, Matchers.containsInAnyOrder("neo4j", "system"));
 
             assertTrue(relationships.isEmpty());
         });
@@ -59,4 +60,19 @@ public class SystemDbTest {
             ));
         });
     }
+
+    @Test
+    public void testExecuteMultipleStatements() {
+        // we have two databases, so asking twice returns 4
+        assertEquals(4, TestUtil.count(db, "CALL apoc.systemdb.execute(['SHOW DATABASES','SHOW DATABASES'])"));
+    }
+
+    @Test
+    public void testWriteStatements() {
+        // count exhaust the result - this is important here
+        TestUtil.count(db, "CALL apoc.systemdb.execute([\"CREATE USER dummy SET PASSWORD '123'\"])");
+
+        assertEquals(2l, TestUtil.count(db, "CALL apoc.systemdb.execute('SHOW USERS')"));
+    }
+
 }