From 689cb90b4fd541726612471bf58e5974147b5b67 Mon Sep 17 00:00:00 2001
From: Matthias Schmidt <gravatronics@live.com>
Date: Sun, 29 Sep 2019 19:07:08 +0200
Subject: [PATCH] Fix default value handling in DB API

---
 .../DatabaseTableChangeProcessor.class.php    | 19 ++++++++++++++++++-
 .../AbstractDatabaseTableColumn.class.php     |  2 +-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php b/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php
index 0e07b14c32..3672aba3c4 100644
--- a/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php
@@ -401,7 +401,7 @@ class DatabaseTableChangeProcessor {
 						}
 						$this->columnsToAdd[$tableName][] = $column;
 					}
-					else if (!empty(array_diff($column->getData(), $existingColumns[$column->getName()]->getData()))) {
+					else if ($this->diffColumns($existingColumns[$column->getName()], $column)) {
 						if (!isset($this->columnsToAlter[$tableName])) {
 							$this->columnsToAlter[$tableName] = [];
 						}
@@ -650,6 +650,23 @@ class DatabaseTableChangeProcessor {
 		]);
 	}
 	
+	/**
+	 * Returns `true` if the two columns differ.
+	 * 
+	 * @param	IDatabaseTableColumn	$oldColumn
+	 * @param	IDatabaseTableColumn	$newColumn
+	 * @return	bool
+	 */
+	protected function diffColumns(IDatabaseTableColumn $oldColumn, IDatabaseTableColumn $newColumn) {
+		if (!empty(array_diff($oldColumn->getData(), $newColumn->getData()))) {
+			return true;
+		}
+		
+		// default type has to be checked with a strict check to differentiate between having
+		// no default value (`null`) and having an empty string as default value
+		return $oldColumn->getDefaultValue() !== $newColumn->getDefaultValue();
+	}
+	
 	/**
 	 * Drops the given foreign key.
 	 * 
diff --git a/wcfsetup/install/files/lib/system/database/table/column/AbstractDatabaseTableColumn.class.php b/wcfsetup/install/files/lib/system/database/table/column/AbstractDatabaseTableColumn.class.php
index 379b661bad..1efa602041 100644
--- a/wcfsetup/install/files/lib/system/database/table/column/AbstractDatabaseTableColumn.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/column/AbstractDatabaseTableColumn.class.php
@@ -54,7 +54,7 @@ abstract class AbstractDatabaseTableColumn implements IDatabaseTableColumn {
 	 */
 	public function getData() {
 		$data = [
-			'default' => $this->defaultValue,
+			'default' => $this->getDefaultValue() !== null ? "'" . str_replace(["'", '\\'], ["''", '\\\\'], $this->getDefaultValue()) . "'" : null,
 			'notNull' => $this->isNotNull() ? 1 : 0,
 			'type' => $this->getType()
 		];
-- 
2.20.1