diff options
Diffstat (limited to 'core/namespace')
| -rw-r--r-- | core/namespace/Application.php | 14 | ||||
| -rw-r--r-- | core/namespace/Migrator.php | 182 |
2 files changed, 196 insertions, 0 deletions
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 $repositories = []; #=============================================================================== @@ -81,6 +82,19 @@ class Application { } #=============================================================================== + # Return singleton Migrator instance + #=============================================================================== + public static function getMigrator(): Migrator { + if(!self::$Migrator instanceof Migrator) { + $Migrator = new Migrator(self::getDatabase()); + $Migrator->setMigrationsDir(ROOT.'core/db/migrations/'); + self::$Migrator = $Migrator; + } + + return self::$Migrator; + } + + #=============================================================================== # Return singleton repository instance #=============================================================================== public static function getRepository(string $namespace): Repository { 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 @@ +<?php +class Migrator { + private $Database; + private $version; + private $directory; + private $migrations = []; + + const CURRENT_SCHEMA_VERSION = 4; + + #=============================================================================== + # Fetch on-disk schema version from migration table + #=============================================================================== + public function __construct(Database $Database) { + $this->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:<br>'; + $error .= sprintf($error, $sequence-1, $sequence); + $error .= sprintf('<code>%s</code>', $Exception->getMessage()); + + if(!empty($migrated ?? [])) { + $error .= '<br>The following migrations were successful: '; + $error .= '<code>'.implode(', ', $migrated).'</code>'; + } + + throw new Exception($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; + } +} |