1 files changed, 17 insertions, 1 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/FunctionalQuery.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/FunctionalQuery.java
index 225f6844..b0a03c7d 100644
--- a/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/FunctionalQuery.java
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/dnf/FunctionalQuery.java
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ * SPDX-FileCopyrightText: 2021-2024 The Refinery Authors <https://refinery.tools/>
  *
  * SPDX-License-Identifier: EPL-2.0
  */
@@ -94,6 +94,22 @@ public final class FunctionalQuery<T> extends Query<T> {
                 return aggregate(aggregator, List.of(arguments));
         }
 
+        public AssignedValue<T> leftJoin(T defaultValue, List<NodeVariable> arguments) {
+                return targetVariable -> {
+                        var placeholderVariable = Variable.of(type);
+                        var argumentsWithPlaceholder = new ArrayList<Variable>(arguments.size() + 1);
+                        argumentsWithPlaceholder.addAll(arguments);
+                        argumentsWithPlaceholder.add(placeholderVariable);
+                        return getDnf()
+                                        .leftJoinBy(placeholderVariable, defaultValue, argumentsWithPlaceholder)
+                                        .toLiteral(targetVariable);
+                };
+        }
+
+        public AssignedValue<T> leftJoin(T defaultValue, NodeVariable... arguments) {
+                return leftJoin(defaultValue, List.of(arguments));
+        }
+
         @Override
         public boolean equals(Object o) {
                 if (this == o) return true;