From 791b250da6d37672320043d678cf0cb431a23944 Mon Sep 17 00:00:00 2001
From: Aidan Saunders <aidan.saunders@squiffle.uk>
Date: Thu, 17 Nov 2022 18:03:57 +0000
Subject: [PATCH] Allow `addTableLink(NULL, ...)`

---
 Civi/Api4/Service/Schema/Joinable/Joinable.php | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/Civi/Api4/Service/Schema/Joinable/Joinable.php b/Civi/Api4/Service/Schema/Joinable/Joinable.php
index 33e2602610..80ed04b6e8 100644
--- a/Civi/Api4/Service/Schema/Joinable/Joinable.php
+++ b/Civi/Api4/Service/Schema/Joinable/Joinable.php
@@ -104,13 +104,15 @@ class Joinable {
    */
   public function getConditionsForJoin(string $baseTableAlias, string $targetTableAlias) {
     $conditions = [];
-    $conditions[] = sprintf(
-      '`%s`.`%s` =  `%s`.`%s`',
-      $baseTableAlias,
-      $this->baseColumn,
-      $targetTableAlias,
-      $this->targetColumn
-    );
+    if ($this->baseColumn && $this->targetColumn) {
+      $conditions[] = sprintf(
+        '`%s`.`%s` =  `%s`.`%s`',
+        $baseTableAlias,
+        $this->baseColumn,
+        $targetTableAlias,
+        $this->targetColumn
+      );
+    }
     $this->addExtraJoinConditions($conditions, $baseTableAlias, $targetTableAlias);
     return $conditions;
   }
-- 
2.25.1