Custom theme breaks Magento admin, fails to register

Question

The theme is installed on a fresh Magento-2.1.7 with no data. The system is CentOS-7.3 (VPS@godaddy), MySQL-5.6.37, PHP-5.6.31, Nginx-1.10, PHP-FPM runs as nginx:nginx, file system user is in the nginx group, directories are "g+s"-ed.

Installation steps: switch to developer mode clean, flush and disable cache, disable js/css merge/minification. ./bin/magento setup:upgrade ./bin/magento index:reindex ./bin/magento cache:clean

Now, the store front page shows up with the Magento's default template, but /admin_****** throws the following exception:

    Exception #0 (Magento\Framework\Exception\FileSystemException): File "/composer.json" cannot be opened Warning!fopen(/composer.json): failed to open stream: No such file or directory
#0 /.../magento2/app/code/TemplateMonster/ThemeUpdater/Model/ThemeData.php(98): Magento\Framework\Filesystem\Driver\File->fileOpen('/composer.json', 'r')
.... 30 lines of the exception trace follow.

Obviously, it is looking for composer.json in the wrong place. The right place is $MAG_ROOT/app/design/frontend/TemplateMonster/theme###/. Here are the relevant parts of ThemeData.php and what I discovered through some hacking into them.

    protected function getComposerData()
    {
        $path       = $this->getAbsThemePath() . '/composer.json';
/*98*/  $resource   = $this->_fileDriver->fileOpen($path, 'r');
        ...
    }

The culprit is line #98. Obviously, getAbsThemePath() returns empty string instead of the theme's full path. Here it is:

    public function getAbsThemePath()
    {
        $theme = $this->_theme->load($this->getThemeId());
        $result = $this->_componentRegistrar->getPath(ComponentRegistrar::THEME, 'frontend/' . $theme->getThemePath() );

        return $result;
    }

public function getThemeId()
    { // should return 4, but returns ''
        return $this->_scopeConfig->getValue(self::DESIGN_THEME_ID, $this->getScopeType(), $this->getScopeId() );
    }

In getThemeId(): runtime arguments to getValue are ('design/theme/theme_id', 'default', null), and getThemeId() returns null (or ''). Actual theme_id in the magento_db.theme table is 4, and if I hard-code getThemeId() to return 4, then everything works. _scopeConfig is injected \Magento\Framework\App\Config\ScopeConfigInterface

Any ideas as to what's going wrong here and how to fix it?

Also, is it worth fighting with it, or should I just get another template from Template Monster (or some other vendor)?

Thank you for your advice.

Answer 1

I just changed the return of the function getThemeId just to make it work:

public function getThemeId()
{
  // FIXME
  // return $this->_scopeConfig->getValue(self::DESIGN_THEME_ID, $this->getScopeType(), $this->getScopeId() );
  return 4;
}

Just make sure what your theme ID is looking into your database: select * from theme:

+----------+-----------+--------------------------+-----------------------+----------------------------------+-------------+-----------+------+--------------------------+
| theme_id | parent_id | theme_path               | theme_title           | preview_image                    | is_featured | area      | type | code                     |
+----------+-----------+--------------------------+-----------------------+----------------------------------+-------------+-----------+------+--------------------------+
|        1 |      NULL | Magento/backend          | Magento 2 backend     | NULL                             |           0 | adminhtml |    0 | Magento/backend          |
|        2 |      NULL | Magento/blank            | Magento Blank         | preview_image_5a132582769c4.jpeg |           0 | frontend  |    0 | Magento/blank            |
|        3 |         2 | Magento/luma             | Magento Luma          | preview_image_5a13258285710.jpeg |           0 | frontend  |    0 | Magento/luma             |
|        4 |      NULL | TemplateMonster/theme063 | TemplateMonster Theme | preview_image_5a132762b07f7.jpeg |           0 | frontend  |    0 | TemplateMonster/theme063 |
+----------+-----------+--------------------------+-----------------------+----------------------------------+-------------+-----------+------+--------------------------+