From dd171566a45b8a5e7d05be12383c2175dcc60241 Mon Sep 17 00:00:00 2001
From: Kenneth Hough <kenneth@keyqcloud.com>
Date: Fri, 24 Apr 2026 21:01:03 -0500
Subject: [PATCH] Fix DBI::buildFieldDefinition to emit DEFAULT NULL for null
 defaults
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Before: a field declared with `'default' => null` generated invalid SQL
because the is_string() check fell through and concatenated null (which
PHP coerces to empty string). Result: `\`language\` varchar(5) DEFAULT  NOT NULL,`
with a dangling space, which MariaDB rejects with a syntax error.

After: emit `DEFAULT NULL` explicitly, which is valid SQL and matches
what `'default' => null` obviously intended.

The Application model's `language` field carries `'default' => null`,
so any fresh call to `DBI::createTable(Application)` has been blowing up
since that field was introduced. The bug hasn't surfaced in production
because existing customer installs created the Application table before
the field was added — only fresh installs hit it.

gust/lib/Database.php carries an identical copy of this bug. Patching
gust's copy is explicitly out of scope for the MCP/auth migration
initiative (see design doc section 11 — gust evaluation) and stays on
the "fix when gust is next touched" list.

Added a characterization test in tests/DatabaseTest.php that creates a
throwaway table with a `'default' => null` column and asserts both
success and `DEFAULT NULL` in the resulting SHOW CREATE TABLE output.
The test explicitly re-selects the kytedev database because the
preceding createDatabase tests leave the mysqli connection without an
active database context.

31/31 unit tests green.
---
 src/Core/DBI.php       |  6 ++++-
 tests/DatabaseTest.php | 57 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/src/Core/DBI.php b/src/Core/DBI.php
index be1ba0d0..48bb9171 100644
--- a/src/Core/DBI.php
+++ b/src/Core/DBI.php
@@ -568,7 +568,11 @@ private static function buildFieldDefinition($name, $attrs, $tableName) {
 		// Default value
 		if (array_key_exists('default', $attrs)) {
 			$field .= ' DEFAULT ';
-			$field .= (is_string($attrs['default']) ? "'" . $attrs['default'] . "'" : $attrs['default']);
+			if (is_null($attrs['default'])) {
+				$field .= 'NULL';
+			} else {
+				$field .= (is_string($attrs['default']) ? "'" . $attrs['default'] . "'" : $attrs['default']);
+			}
 		}
 
 		// Required/NOT NULL
diff --git a/tests/DatabaseTest.php b/tests/DatabaseTest.php
index 1c7ef5f4..3ee4289d 100644
--- a/tests/DatabaseTest.php
+++ b/tests/DatabaseTest.php
@@ -23,4 +23,61 @@ public function testDatabaseCreationAndSwitch() {
         $password = null;
         $this->assertTrue(\Kyte\Core\DBI::createDatabase("TestDatabase2", "TestUser2", $password, true));
     }
+
+    /**
+     * Regression test: createTable must accept fields declared with
+     * 'default' => null and emit DEFAULT NULL in the generated SQL.
+     *
+     * Before this was fixed, buildFieldDefinition's default-value branch fell
+     * through to a fall-through concat that coerced null to '', producing
+     * broken SQL like `language varchar(5) DEFAULT  NOT NULL,`. The Application
+     * model's `language` field has 'default' => null, so any fresh createTable
+     * of it (e.g. during install) blew up. gust/lib/Database.php still has an
+     * identical copy of this bug and should be patched when gust is next
+     * touched (see design doc section 11, gust evaluation).
+     */
+    public function testCreateTableAcceptsNullDefault() {
+        // The preceding createDatabase tests leave the mysqli connection
+        // without an active database context. Re-select kytedev explicitly.
+        // dbInit won't help here because connect() early-returns once a
+        // connection object already exists.
+        \Kyte\Core\DBI::query('USE `' . KYTE_DB_DATABASE . '`');
+
+        $tblName = 'NullDefaultProbe_' . substr(bin2hex(random_bytes(4)), 0, 8);
+
+        $modelDef = [
+            'name' => $tblName,
+            'struct' => [
+                'id' => [
+                    'type'     => 'i',
+                    'required' => true,
+                    'pk'       => true,
+                    'size'     => 11,
+                    'date'     => false,
+                ],
+                'optional_label' => [
+                    'type'     => 's',
+                    'required' => false,
+                    'size'     => 64,
+                    'date'     => false,
+                    'default'  => null,
+                ],
+            ],
+        ];
+
+        try {
+            $this->assertTrue(\Kyte\Core\DBI::createTable($modelDef));
+
+            $rows = \Kyte\Core\DBI::query("SHOW CREATE TABLE `$tblName`");
+            $this->assertNotEmpty($rows);
+            $createSql = $rows[0]['Create Table'] ?? '';
+            $this->assertStringContainsStringIgnoringCase(
+                'DEFAULT NULL',
+                $createSql,
+                "Column with 'default' => null should surface as DEFAULT NULL in SHOW CREATE TABLE output."
+            );
+        } finally {
+            \Kyte\Core\DBI::query("DROP TABLE IF EXISTS `$tblName`");
+        }
+    }
 }