默认情况下，在Magento 2中，后台管理没有选项可以更改创建后的产品属性类型。因此，我们必须创建自定义脚本来更改产品属性类型。以下示例代码将帮助您将产品属性类型从文本更改为Magento 2中的下拉列表。

另请阅读：  通过InstallData.php在Magento 2中创建自定义属性组和产品属性

以下是我们在以下示例中遵循的步骤，

  • 将我们要更改的属性ID从文本更改为下拉列表
  • 获取已存储在数据库中的给定属性Id的产品值
  • 对于给定的属性Id，将先前存储的产品值作为选项插入数据库表“eav_attribute_option”和“eav_attribute_option_value”
  • 使用选项Id将插入的属性选项分配给适当的产品
  • 最后，使用UPDATE查询将属性类型从文本更改为数据库下拉列表
<?php
use Magento\Framework\App\Bootstrap;
 
/**
 * If the external file is in the root folder
 */
require __DIR__ . '/app/bootstrap.php';
 
$params = $_SERVER;
$bootstrap = Bootstrap::create(BP, $params);
$obj = $bootstrap->getObjectManager();
 
$state = $obj->get('Magento\Framework\App\State');
$state->setAreaCode('frontend');
  
/*
 * Instance of object manager
 */
$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
 
/*
 * Attribute Id that we want to change from text to dropdown
 */
$attributeId = 155;  
 
$resource = $objectManager->get('Magento\Framework\App\ResourceConnection');
$connection = $resource->getConnection();
  
/*
 * Get the product values that are already stored in the database for given attribute
 */
$catalog_product_entity_varchar = $resource->getTableName('catalog_product_entity_varchar');
$attribute_values = $connection->fetchAll("SELECT DISTINCT attribute_id, value FROM $catalog_product_entity_varchar where attribute_id = $attributeId"); 
if(!empty($attribute_values)) {
    foreach ($attribute_values as $_attribute_values) {
 
        $attribute_values = $connection->fetchRow("SELECT count(*) as cnt FROM `eav_attribute_option` where attribute_id = $attributeId;");
        $count = $attribute_values['cnt'] + 1;
 
        /*
         * Insert previously stored product values as an option on the database for a given attribute
         */
        $eav_attribute_option = $resource->getTableName('eav_attribute_option');
        $sql = "insert into $eav_attribute_option(option_id, attribute_id, sort_order) values (null, $attributeId, $count)";
        try {
            $resp = $connection->query($sql);
        } catch (Exception $e) {
            echo '
';  print_r($e->getMessage());
        }
        $lastInsertId = $connection->lastInsertId();
 
        $eav_attribute_option_value = $resource->getTableName('eav_attribute_option_value');
        $sql = "insert into $eav_attribute_option_value(value_id, option_id, store_id, value) values (null, $lastInsertId, 0, '$_attribute_values[value]')";
        try {
            $resp = $connection->query($sql);
        } catch (Exception $e) {
            echo '
';  print_r($e->getMessage());
        }
 
        $sql = "insert into $eav_attribute_option_value(value_id, option_id, store_id, value) values (null, $lastInsertId, 1, '$_attribute_values[value]')";
        try {
            $resp = $connection->query($sql);
        } catch (Exception $e) {
            echo '
';  print_r($e->getMessage());
        }
    }
}
  
$catalog_product_entity_varchar = $resource->getTableName('catalog_product_entity_varchar');
$attribute_values = $connection->fetchAll("SELECT * FROM $catalog_product_entity_varchar where attribute_id = $attributeId"); 
if(!empty($attribute_values)) {
    foreach ($attribute_values as $_attribute_values) {
 
        /*
         * Get the option id for the specific product
         */
        $option_values = $connection->fetchRow("SELECT * FROM `eav_attribute_option` as eao INNER JOIN `eav_attribute_option_value` as eaov on eao.option_id = eaov.option_id WHERE eao.attribute_id = $attributeId and eaov.store_id = 1 and eaov.value = '$_attribute_values[value]'");
 
        if(!empty($option_values)) {
            $catalog_product_entity_int = $resource->getTableName('catalog_product_entity_int');
            $product_values_exist = $connection->fetchRow("SELECT value_id FROM $catalog_product_entity_int WHERE attribute_id = $attributeId and entity_id = $_attribute_values[entity_id]");
 
            if(empty($product_values_exist)) {
                $sql = "insert into $catalog_product_entity_int(value_id, attribute_id, store_id, entity_id, value) values (null, $attributeId, 0, $_attribute_values[entity_id], $option_values[option_id])";
                try {
                    $resp = $connection->query($sql);
                } catch (Exception $e) {
                    echo '
';  print_r($e->getMessage());
                }
            } else {
                $sql = "Update $catalog_product_entity_int set value = $option_values[option_id] WHERE attribute_id = $attributeId and entity_id = $_attribute_values[entity_id]";
                try {
                    $resp = $connection->query($sql);
                } catch (Exception $e) {
                    echo '
';  print_r($e->getMessage());
                }
            }
        }
    }
}
  
/*
 * Change the attribute type from text to dropdown on database
 */
$eav_attribute = $resource->getTableName('eav_attribute');
$sql = "UPDATE $eav_attribute SET `backend_type` = 'int', `frontend_input` = 'select', `source_model` = 'Magento\\\Eav\\\Model\\\Entity\\\Attribute\\\Source\\\Table' WHERE `attribute_id` = $attributeId";
try {
    $resp = $connection->query($sql);
} catch (Exception $e) {
    echo '
'; print_r($e->getMessage());
}
  
$catalog_eav_attribute = $resource->getTableName('catalog_eav_attribute');
$sql = "UPDATE $catalog_eav_attribute SET `is_filterable` = 1, is_comparable = 1, is_visible_on_front = 1, is_html_allowed_on_front = 1, is_filterable_in_search = 1, used_in_product_listing = 1 WHERE `attribute_id` = $attributeId";
try {
    $resp = $connection->query($sql);
} catch (Exception $e) {
    echo '
'; print_r($e->getMessage());
}



希望这可以帮助到你。