From d69d7e82b8bbb567668c935ace848c7dcf750b08 Mon Sep 17 00:00:00 2001 From: Thomas Lange Date: Thu, 24 Jun 2021 21:09:24 +0200 Subject: Implement database schema Migrator This commit implements the new database schema Migrator which keeps track of the on-disk schema and the schema used by the codebase. It tries to makes future database schema upgrades user-friendlier. --- core/application.php | 5 ++ core/migrations.php | 43 ++++++++++ core/namespace/Application.php | 14 ++++ core/namespace/Migrator.php | 182 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 244 insertions(+) create mode 100644 core/migrations.php create mode 100644 core/namespace/Migrator.php (limited to 'core') diff --git a/core/application.php b/core/application.php index 21ab203..d6c9bd0 100644 --- a/core/application.php +++ b/core/application.php @@ -141,6 +141,11 @@ require 'functions.php'; $Language = Application::getLanguage(); $Database = Application::getDatabase(); +#=============================================================================== +# Include migration detection +#=============================================================================== +require 'migrations.php'; + #=============================================================================== # Check if "304 Not Modified" and ETag header should be sent #=============================================================================== diff --git a/core/migrations.php b/core/migrations.php new file mode 100644 index 0000000..f2c9714 --- /dev/null +++ b/core/migrations.php @@ -0,0 +1,43 @@ +isMigrationNeeded()) { + @session_start(); + + Application::set('TEMPLATE.NAME', Application::get('ADMIN.TEMPLATE')); + Application::set('TEMPLATE.LANG', Application::get('ADMIN.LANGUAGE')); + Application::getLanguage(TRUE); // Force recreation of Language object + + if(HTTP::issetPOST(['token' => Application::getSecurityToken()], 'run')) { + if(!$migrated = $Migrator->runMigrations()) { + Application::exit('CONFUSED: No migrations were performed?!'); + } + } + + $Template = Template\Factory::build('migration'); + $Template->set('MIGRATION', [ + 'LIST' => $Migrator->getMigrations(), + 'SUCCESSFUL' => $migrated ?? [], + 'SCHEMA_VERSION' => [ + 'DATABASE' => $Migrator->getVersionFromTable(), + 'CODEBASE' => $Migrator::CURRENT_SCHEMA_VERSION + ], + ]); + + Application::exit($Template); +} + +#=============================================================================== +# Check for an unsupported downgrade attempt +#=============================================================================== +else if($Migrator->isDowngradeAttempt()) { + throw new Exception('MIGRATOR: The schema version used by *your* database is + higher than the schema version defined in the codebase. It is officially + not supported to automatically downgrade the database schema version!'); +} diff --git a/core/namespace/Application.php b/core/namespace/Application.php index 3cecf3b..829f758 100644 --- a/core/namespace/Application.php +++ b/core/namespace/Application.php @@ -6,6 +6,7 @@ class Application { #=============================================================================== private static $Database; private static $Language; + private static $Migrator; private static $repositories = []; #=============================================================================== @@ -80,6 +81,19 @@ class Application { return self::$Language; } + #=============================================================================== + # Return singleton Migrator instance + #=============================================================================== + public static function getMigrator(): Migrator { + if(!self::$Migrator instanceof Migrator) { + $Migrator = new Migrator(self::getDatabase()); + $Migrator->setMigrationsDir(ROOT.'core/db/migrations/'); + self::$Migrator = $Migrator; + } + + return self::$Migrator; + } + #=============================================================================== # Return singleton repository instance #=============================================================================== diff --git a/core/namespace/Migrator.php b/core/namespace/Migrator.php new file mode 100644 index 0000000..3096862 --- /dev/null +++ b/core/namespace/Migrator.php @@ -0,0 +1,182 @@ +Database = $Database; + + try { + $Statement = $Database->query('SELECT schema_version FROM migration'); + + if(!$this->version = $Statement->fetchColumn()) { + throw new Exception('The migration table does exist, but there is + no row containing the currently used on-disk schema version!'); + } + } catch(PDOException $Exception) { + if($Exception->getCode() === '42S02') /* Table not found */ { + $this->version = $this->determineFallbackSchemaVersion(); + $this->createMigrationTable($this->version); + } else { + throw $Exception; + } + } + } + + #=============================================================================== + # Specify the directory which contains the migration files + #=============================================================================== + public function setMigrationsDir(string $directory): void { + if(!is_readable($this->directory = rtrim($directory, '/'))) { + throw new Exception('Migrator cannot read migration directory.'); + }; + } + + #=============================================================================== + # Check if new migrations needs to be applied + #=============================================================================== + public function isMigrationNeeded(): bool { + $databaseSchema = $this->version; + $codebaseSchema = self::CURRENT_SCHEMA_VERSION; + return $databaseSchema < $codebaseSchema; + } + + #=============================================================================== + # Check if this is an unsupported downgrade attempt + #=============================================================================== + public function isDowngradeAttempt(): bool { + $databaseSchema = $this->version; + $codebaseSchema = self::CURRENT_SCHEMA_VERSION; + return $databaseSchema > $codebaseSchema; + } + + #=============================================================================== + # Add a migration to the queue + #=============================================================================== + private function enqueue(int $sequence, string $migration): void { + $this->migrations[$sequence] = $migration; + } + + #=============================================================================== + # Remove a migration from the queue + #=============================================================================== + private function dequeue(int $sequence): void { + unset($this->migrations[$sequence]); + } + + #=============================================================================== + # Get the currently used on-disk schema version + #=============================================================================== + public function getVersionFromTable(): int { + return $this->version; + } + + #=============================================================================== + # Get an array with all migration commands + #=============================================================================== + public function getMigrations(): array { + $databaseSchema = $this->version; + $codebaseSchema = self::CURRENT_SCHEMA_VERSION; + + if(!$this->isMigrationNeeded()) { + return []; + } + + foreach(range($databaseSchema+1, $codebaseSchema) as $number) { + $file = sprintf("%s/%d.sql", $this->directory, $number); + + if(!is_readable($file)) { + throw new Exception("Migrator cannot read migration file: »{$file}«"); + } + $this->enqueue($number, file_get_contents($file)); + } + + return $this->migrations; + } + + #=============================================================================== + # Run migrations sequentially + #=============================================================================== + public function runMigrations(): array { + foreach($this->getMigrations() as $sequence => $migration) { + try { + if($this->Database->query($migration)) { + $this->dequeue($sequence); + $this->updateMigrationTable($sequence); + $migrated[] = $sequence; + } + } catch(PDOException $Exception) { + $error = 'Migration from %d to %d failed with PDO error:
'; + $error .= sprintf($error, $sequence-1, $sequence); + $error .= sprintf('%s', $Exception->getMessage()); + + if(!empty($migrated ?? [])) { + $error .= '
The following migrations were successful: '; + $error .= ''.implode(', ', $migrated).''; + } + + throw new Exception($error); + } + } + + return $migrated ?? []; + } + + #=============================================================================== + # Update the migration table with the specified schema version + #=============================================================================== + private function updateMigrationTable(int $version): int { + $query = 'UPDATE migration SET schema_version = ?'; + $Statement = $this->Database->prepare($query); + + if($Statement->execute([$version])) { + return $this->version = $version; + } + } + + #=============================================================================== + # Create the migration table with the specified schema version + #=============================================================================== + private function createMigrationTable(int $version): bool { + $create = 'CREATE TABLE migration (schema_version smallint(4) NOT NULL) + ENGINE=InnoDB DEFAULT CHARSET=utf8mb4'; + $insert = 'INSERT INTO migration (schema_version) VALUES (?)'; + + $this->Database->query($create); + $Statement = $this->Database->prepare($insert); + + return $Statement->execute([$version]); + } + + #=============================================================================== + # Determine on-disk schema version if migration table does not exist + #=============================================================================== + private function determineFallbackSchemaVersion(): int { + # If the migration table does not yet exist, the user may have upgraded from + # an older release of the application and sits somewhere between 0 and 4. So + # we run some checks against the tables to determine the schema version. + $test[4] = 'SHOW COLUMNS FROM post WHERE Field = "argv" AND Type = "varchar(250)"'; + $test[3] = 'SHOW INDEX FROM post WHERE Key_name = "search"'; + $test[2] = 'SHOW INDEX FROM post WHERE Key_name = "time_insert"'; + $test[1] = 'SHOW COLUMNS FROM post WHERE Field = "argv"'; + + foreach($test as $version => $query) { + try { + $Statement = $this->Database->query($query); + + if ($Statement && $Statement->fetch()) { + return $version; + } + } catch(PDOException $Exception) {} + } + + return 0; + } +} -- cgit v1.2.3