无主键实体的对称原则模型

Question

我正在重建web应用程序时使用遗留数据库。我想用Symfony2。x，其中显然有Doctrine作为ORM。

我有大约50 (mysql)表没有主键。当我尝试生成模型时，它不让我这样做，并抛出一个异常"No Primary Key on…"表"。

我必须在表上有主键才能使用Doctrine吗?或者有其他方法吗?

任何帮助都太好了。

谢谢。

Answer 1

原则要求每个实体类都有一个标识符/主键。

看看这个页面:http://www.doctrine-project.org/docs/orm/2.0/en/reference/basic-mapping.html#identifiers-primary-keys

Answer 2

Doctrine需要有一个标识符/主键。看看这个页面:http://www.doctrine-project.org/docs/orm/2.0/en/reference/basic-mapping.html#identifiers-primary-keys

但是是一种从没有主键的表生成映射和实体的方法。没有主键的表是一种不寻常的糟糕的数据库设计，但在遗留数据库中存在这种情况。

<<p> 解决方案/strong>:
注:以下所有引用均参考Doctrine 2.0
1. 查找文件DatabaseDriver.php(在Doctrine/ORM/Mapping/Driver/DatabaseDriver.php中)
2. 找到方法reverseEngineerMappingFromDatabase。按如下所述修改代码。
原代码为:

private function reverseEngineerMappingFromDatabase()
    {
        if ($this->tables !== null) {
            return;
        }
        $tables = array();
        foreach ($this->_sm->listTableNames() as $tableName) {
            $tables[$tableName] = $this->_sm->listTableDetails($tableName);
        }
        $this->tables = $this->manyToManyTables = $this->classToTableNames = array();
        foreach ($tables as $tableName => $table) {
            /* @var $table DoctrineDBALSchemaTable */
            if ($this->_sm->getDatabasePlatform()->supportsForeignKeyConstraints()) {
                $foreignKeys = $table->getForeignKeys();
            } else {
                $foreignKeys = array();
            }
            $allForeignKeyColumns = array();
            foreach ($foreignKeys as $foreignKey) {
                $allForeignKeyColumns = array_merge($allForeignKeyColumns, $foreignKey->getLocalColumns());
            }
            if ( ! $table->hasPrimaryKey()) {
                throw new MappingException(
                    "Table " . $table->getName() . " has no primary key. Doctrine does not ".
                    "support reverse engineering from tables that don't have a primary key."
                );
            }
            $pkColumns = $table->getPrimaryKey()->getColumns();
            sort($pkColumns);
            sort($allForeignKeyColumns);
            if ($pkColumns == $allForeignKeyColumns && count($foreignKeys) == 2) {
                $this->manyToManyTables[$tableName] = $table;
            } else {
                // lower-casing is necessary because of Oracle Uppercase Tablenames,
                // assumption is lower-case + underscore separated.
                $className = $this->getClassNameForTable($tableName);
                $this->tables[$tableName] = $table;
                $this->classToTableNames[$className] = $tableName;
            }
        }
    }

修改后的代码为:

private function reverseEngineerMappingFromDatabase()
    {
        if ($this->tables !== null) {
            return;
        }
        $tables = array();
        foreach ($this->_sm->listTableNames() as $tableName) {
            $tables[$tableName] = $this->_sm->listTableDetails($tableName);
        }
        $this->tables = $this->manyToManyTables = $this->classToTableNames = array();
        foreach ($tables as $tableName => $table) {
            /* @var $table DoctrineDBALSchemaTable */
            if ($this->_sm->getDatabasePlatform()->supportsForeignKeyConstraints()) {
                $foreignKeys = $table->getForeignKeys();
            } else {
                $foreignKeys = array();
            }
            $allForeignKeyColumns = array();
            foreach ($foreignKeys as $foreignKey) {
                $allForeignKeyColumns = array_merge($allForeignKeyColumns, $foreignKey->getLocalColumns());
            }
            $pkColumns=array();
            if ($table->hasPrimaryKey()) {
                $pkColumns = $table->getPrimaryKey()->getColumns();
                sort($pkColumns);
            }
            sort($allForeignKeyColumns);
            if ($pkColumns == $allForeignKeyColumns && count($foreignKeys) == 2) {
                $this->manyToManyTables[$tableName] = $table;
            } else {
                // lower-casing is necessary because of Oracle Uppercase Tablenames,
                // assumption is lower-case + underscore separated.
                $className = $this->getClassNameForTable($tableName);
                $this->tables[$tableName] = $table;
                $this->classToTableNames[$className] = $tableName;
            }
        }
    }

3.在同一文件中找到方法loadMetadataForClass。按如下所述修改代码。
查找如下代码:

try {
   $primaryKeyColumns = $this->tables[$tableName]->getPrimaryKey()->getColumns();
} catch(SchemaException $e) {
    $primaryKeyColumns = array();
}

修改如下:

try {
     $primaryKeyColumns = ($this->tables[$tableName]->hasPrimaryKey())?$this->tables[$tableName]->getPrimaryKey()->getColumns():array();
} catch(SchemaException $e) {
     $primaryKeyColumns = array();
}

上面的解决方案甚至为没有主键的表创建映射(xml/yml/annotation)。