From 236737d5c7cff529f06948a6994d284b81f4d5b7 Mon Sep 17 00:00:00 2001
From: Coleman Watts <coleman@civicrm.org>
Date: Thu, 20 Jan 2022 16:34:48 -0500
Subject: [PATCH] APIv4 - Use empty string instead of 'null' to pass null
 values to the database

`CRM_Core_DAO::copyValues()` already converts '' to 'null', and passing the string 'null'
into `BAO::writeRecords` or `BAO::create` functions prematurely can introduce subtle bugs
because the string 'null' is `!empty()` whereas '' is `empty()`.
---
 Civi/Api4/Generic/Traits/DAOActionTrait.php | 4 ++--
 Civi/Api4/Utils/FormattingUtil.php          | 5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Civi/Api4/Generic/Traits/DAOActionTrait.php b/Civi/Api4/Generic/Traits/DAOActionTrait.php
index 201f4c2ab9..b44c7d1fda 100644
--- a/Civi/Api4/Generic/Traits/DAOActionTrait.php
+++ b/Civi/Api4/Generic/Traits/DAOActionTrait.php
@@ -60,8 +60,8 @@ trait DAOActionTrait {
     else {
       $inputFields = array_keys($input);
       // Convert 'null' input to true null
-      foreach ($input as $key => $val) {
-        if ($val === 'null') {
+      foreach ($inputFields as $key) {
+        if (($bao->$key ?? NULL) === 'null') {
           $bao->$key = NULL;
         }
       }
diff --git a/Civi/Api4/Utils/FormattingUtil.php b/Civi/Api4/Utils/FormattingUtil.php
index f537e73b5e..6d4af31ed1 100644
--- a/Civi/Api4/Utils/FormattingUtil.php
+++ b/Civi/Api4/Utils/FormattingUtil.php
@@ -56,7 +56,8 @@ class FormattingUtil {
       /*
        * Because of the wacky way that database values are saved we need to format
        * some of the values here. In this strange world the string 'null' is used to
-       * unset values. Hence if we encounter true null we change it to string 'null'.
+       * unset values. If we encounter true null at this layer we change it to an empty string
+       * and it will be converted to 'null' by CRM_Core_DAO::copyValues.
        *
        * If we encounter the string 'null' then we assume the user actually wants to
        * set the value to string null. However since the string null is reserved for
@@ -66,7 +67,7 @@ class FormattingUtil {
        * 'Null'.
        */
       elseif (array_key_exists($name, $params) && $params[$name] === NULL) {
-        $params[$name] = 'null';
+        $params[$name] = '';
       }
     }
 
-- 
2.25.1