Magento2 InstallSchema Error 1215

Question

I am trying to create InstallSchema script in magento2. However, I get the fallowing error:

SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint

The code is as fallows:

$table = $installer->getConnection()
                            ->newTable($installer->getTable('gift_products'))
                            ->addColumn(
                                    'gift_id',
                                    \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
                                    null,
                                    ['identity' => true, 'unsigned' => true, 'nullable' => false, 'primary' => true],
                                    'Gift Id'
                            )
                            ->addColumn(
                                    'store_id',
                                    \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
                                    null,
                                    ['unsigned' =>  true, 'nullable' => true],
                                    'Store Id'
                            )
                            ->addColumn(
                                    'entity_id',
                                    \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
                                    null,
                                    ['unsigned' =>  true, 'nullable' => true],
                                    'Product Id'
                            )
                            ->addColumn(
                                    'priority',
                                    \Magento\Framework\DB\Ddl\Table::TYPE_INTEGER,
                                    null,
                                    ['unsigned' =>  true],
                                    'Gift priority'
                            )
                            ->addIndex(
                                    $installer->getIdxName('gift_products', ['gift_id']),
                                    ['gift_id']
                            )
                            ->addIndex(
                                    $installer->getIdxName('gift_products', ['priority']),
                                    ['priority']
                            )
                            ->addForeignKey(
                                    $installer->getFkName('gift_products', 'store_id', 'store', 'store_id'),
                                    'store_id',
                                    $installer->getTable('store'),
                                    'store_id',
                                    \Magento\Framework\DB\Ddl\Table::ACTION_CASCADE
                            )
                            ->addForeignKey(
                                    $installer->getFkName('gift_products', 'entity_id', 'catalog_product_entity',   'entity_id'),
                                    'entity_id',
                                    $installer->getTable('catalog_product_entity'),
                                    'entity_id',
                                    \Magento\Framework\DB\Ddl\Table::ACTION_CASCADE
                            )
                            ->setComment('Gift module table');

The generated query is :

CREATE TABLE IF NOT EXISTS `gift_products` (                           
    `gift_id` int UNSIGNED NOT NULL auto_increment COMMENT 'Gift Id' ,                                                                                      
    `store_id` int UNSIGNED NULL COMMENT 'Store Id' ,                                                                                                       
    `entity_id` int UNSIGNED NULL COMMENT 'Product Id' ,                                                                                                    
    `priority` int UNSIGNED NULL COMMENT 'Gift priority' ,                                                                                                  
    PRIMARY KEY (`gift_id`),                                                                                                                                
    INDEX `GIFT_PRODUCTS_GIFT_ID` (`gift_id`),                                                                                                              
    INDEX `GIFT_PRODUCTS_PRIORITY` (`priority`),                                                                                                            
    CONSTRAINT `GIFT_PRODUCTS_STORE_ID_STORE_STORE_ID` FOREIGN KEY (`store_id`) REFERENCES `store` (`store_id`) ON DELETE CASCADE,                          
    CONSTRAINT `GIFT_PRODUCTS_ENTITY_ID_CATALOG_PRODUCT_ENTITY_ENTITY_ID` FOREIGN KEY (`entity_id`) REFERENCES `catalog_product_entity` (`entity_id`) ON DELETE CASCADE                                                                                                                                             
  ) COMMENT='Gift module table' ENGINE=INNODB charset=utf8 COLLATE=utf8_general_ci

Where is the problem ?

Answer 1

data type for the child column must match the parent column exactly. check data type in table store store_id (type is smallint) and your store_id is INTEGER.

Answer 2

if you have taken the backup of same table and if foreign key constraint is same as bkp table and current table mysql will throw exception, so change the constraint name or delete the existing constraint