./bin/magento config:show fails with a fatal error

[simonworkhouse]

The ./bin/magento config:show command fails with a fatal error after running ./bin/magento app:config:dump
Similar issue reported previously #16654

Preconditions

1. Magento 2.2.5
2. PHP 7.1.20
3. MySQL 5.7.23

Steps to reproduce

1. composer create-project --repository-url=https://repo.magento.com/ magento/project-community-edition {install dir}
2. cd {install dir}
3. ./bin/magento setup:install --backend-frontname=? --db-host=? --db-name=? --db-user=? --db-password=? --base-url=? --admin-user=? --admin-password=? --admin-email=? --admin-firstname=? --admin-lastname=?
4. ./bin/magento app:config:dump
5. ./bin/magento config:show

Expected result

All config data output correctly without a fatal error.

Actual result

...
catalog/productalert_cron/error_email -
catalog/product_video/play_if_base - 0
catalog/product_video/show_related - 0
catalog/product_video/video_auto_restart - 0
catalog/review/allow_guest - 1
catalog/search/engine - mysql
catalog/search/min_query_length - 1
catalog/search/max_query_length - 128
catalog/search/max_count_cacheable_search_terms - 100
analytics/subscription/enabled - 1
PHP Fatal error: Uncaught Error: Call to undefined method Magento\Config\Model\Config\Structure\Element\Group\Interceptor::hasBackendModel() in /vendor/magento/module-config/Console/Command/ConfigShow/ValueProcessor.php:100
Stack trace:
#0 /vendor/magento/module-config/Console/Command/ConfigShowCommand.php(197): Magento\Config\Console\Command\ConfigShow\ValueProcessor->process('default', '', 'Magento Analyti...', 'analytics/integ...')
#1 /vendor/magento/module-config/Console/Command/ConfigShowCommand.php(202): Magento\Config\Console\Command\ConfigShowCommand->outputResult(Object(Symfony\Component\Console\Output\ConsoleOutput), 'Magento Analyti...', 'analytics/integ...')
#2 /vendor/magento/module-config/Console/Command/ConfigShowCommand.php(202): Magento\Config\Console\Command\ConfigShow in /vendor/magento/module-config/Console/Command/ConfigShow/ValueProcessor.php on line 100

[magento-engcom-team]

Hi @simonworkhouse. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

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where {$VERSION} is version tags (starting from 2.2.0+) or develop branches (2.2-develop +).
For more details, please, review the Magento Contributor Assistant documentation.

@simonworkhouse do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

@simonworkhouse , thank you for your report.
We've acknowledged the issue and added to our backlog.

[leoquijano]

Hi,

I also encountered this issue. My Magento version is v2.2.5. In my case, this happens when config:show tries to display the value of dashboard/use_aggregated_data from app/etc/config.php:

'system' => [
  'default' => [
     // ...
     'dashboard' => [
        'use_aggregated_data' => '0',
     ],
     // ...
  ]
]

It seems that Magento\Config\Console\Command\ConfigShow::process is assuming that the Magento\Config\Model\Config\Structure::getElementByConfigPath method will always return an instance of Magento\Config\Model\Config\Structure\Element\Field:

public function process($scope, $scopeCode, $value, $path)
{
    // ...
    /** @var Field $field */
    $field = $configStructure->getElementByConfigPath($path);

    /** @var Value $backendModel */
    $backendModel = $field && $field->hasBackendModel()
        ? $field->getBackendModel()
        : $this->configValueFactory->create();

    // ...
}

However, it actually returns an instance of \Magento\Config\Model\Config\Structure\ElementInterface (note the @return PHPDoc tag):

/**
 * Find element by config path
 *
 * @param string $path The configuration path
 * @return \Magento\Config\Model\Config\Structure\ElementInterface|null
 * @since 100.2.0
 */
public function getElementByConfigPath($path)
{
    $allPaths = $this->getFieldPaths();

    if (isset($allPaths[$path])) {
        $path = array_shift($allPaths[$path]);
    }

    return $this->getElementByPathParts(explode('/', $path));
}

In the case of dashboard/use_aggregated_data, the returned element is actually an instance of Magento\Config\Model\Config\Structure\Element\Group, which doesn't have the hasBackendModel method. This triggers a fatal error by PHP.

A fix could be either adjusting the process field to handle group elements, or making getElementByConfigPath only return field elements. A quick workaround while the bug gets fixed is to remove the offending entry from app/etc/config:

 'dashboard' => [
    'use_aggregated_data' => '0',
 ],

If the entry is required to be there, then a temporary adjustment to the process method above might help.

[max-a-mdmitriev]

#khcd2018

[magento-engcom-team]

@max-a-mdmitriev thank you for joining. Please accept team invitation here and self-assign the issue.