GH113 - Allow conditions based on path patterns on pattern comprehens…

…ions.

neo4j-cypher-dsl/src/main/java/org/neo4j/cypherdsl/core/PatternComprehension.java

@@ -80,6 +80,21 @@ public interface OngoingDefinitionWithPattern extends OngoingDefinitionWithoutRe
 		 * @return An ongoing definition of a pattern comprehension for furhter modification
 		 */
 		OngoingDefinitionWithPatternAndWhere where(Condition condition);
+
+		/**
+		 * Adds a where clause based on a path pattern to the ongoing definition
+		 *
+		 * @param pathPattern The path pattern to add to the where clause.
+		 *                    This path pattern must not be {@literal null} and must
+		 *                    not introduce new variables not available in the match.
+		 * @return A match or a call restricted by a where clause with no return items yet.
+		 * @since 2020.1.4
+		 */
+		default OngoingDefinitionWithPatternAndWhere where(RelationshipPattern pathPattern) {
+
+			Assertions.notNull(pathPattern, "The path pattern must not be null.");
+			return this.where(new RelationshipPatternCondition(pathPattern));
+		}
 	}
 
 	/**

neo4j-cypher-dsl/src/test/java/org/neo4j/cypherdsl/core/CypherIT.java

@@ -1391,6 +1391,22 @@ void doc3653() {
 					.isEqualTo("MATCH (n:`Person`) WHERE (n)-[:`KNOWS`]-( {name: 'Timothy'}) RETURN n.name, n.age");
 			}
 
+			@Test
+			void gh113() {
+
+				Node foo = Cypher.node("Foo").named("foo");
+				Node bar = Cypher.node("Bar").named("bar");
+				Relationship fooBar = foo.relationshipTo(bar, "FOOBAR").named("rel");
+				PatternComprehension pc = Cypher.listBasedOn(fooBar)
+					.where(bar.relationshipTo(Cypher.node("ZZZ"), "HAS"))
+					.returning(fooBar, bar);
+				Statement statement = Cypher.match(foo).returning(foo.getRequiredSymbolicName(),  pc).build();
+
+				assertThat(cypherRenderer.render(statement)).isEqualTo(
+					"MATCH (foo:`Foo`) RETURN foo, [(foo)-[rel:`FOOBAR`]->(bar:`Bar`) WHERE (bar)-[:`HAS`]->(:`ZZZ`) | [rel, bar]]"
+				);
+			}
+
 			@Test
 			void doc3654() {