Early Stage Plugins/Interceptors Don’t Work in Developer Mode · Issue #2674 · magento/magento2

This one was fun to track down. I was trying to plugin to Magento’s logger (MagentoFrameworkLoggerMonolog) but my plugin wasn’t working. Being new to Magento, I assumed the problem was an incorrect configuration, but everything seemed ok. Madness. After a spelunk down into the bowels of Magento’s object manager code, I found the problem. If developer mode is enabled, there are certain classes you won’t be able to plugin to.

The short short version – pre-generate your classes like you would before deploying to production

php bin/magento setup:di:compile

The medium short version: In developer mode the object manager will dynamically generate the Interceptor classes Magento uses to implement plugins. However, Magento uses the object manager before it has loaded all the di.xml files, and these di.xml files are where plugins are configured. If the object manager has instantiated a singleton/single-instance object – this means post di.xml loading it will still return the original, non-intercepted classes.

Classic bootstrap chicken/egg situation.

The setup:di:compile command analyzes your Magento system and pre-generates any extra classes that are needed. There’s no automatic code generation when Magento’s running in production mode.

Here’s a quick list of classes you can’t “developer mode plugin to” in a stock 2.0 system. Keep in mind this may change if there’s additional classes you and/or Magento instantiates during the early bootstrap stages.

MagentoFrameworkAppObjectManagerConfigLoader
MagentoFrameworkAppCacheTypeConfig
MagentoFrameworkAppCacheTypeFrontendPool
MagentoFrameworkAppCacheFrontendPool
MagentoFrameworkAppCacheFrontendFactory
MagentoFrameworkFilesystem
MagentoFrameworkFilesystemDirectoryReadFactory
MagentoFrameworkFilesystemDirectoryWriteFactory
MagentoFrameworkAppResourceConnectionProxy
MagentoFrameworkObjectManagerConfigReaderDomFactory
MagentoFrameworkAppObjectManagerConfigCache
MagentoFrameworkCacheFrontendAdapterZend
MagentoFrameworkCacheFrontendDecoratorTagScope
MagentoFrameworkCacheFrontendDecoratorLogger
MagentoFrameworkCacheInvalidateLogger
MagentoFrameworkAppRequestHttp
MagentoFrameworkStdlibCookiePhpCookieReader
MagentoFrameworkStdlibStringUtils
MagentoFrameworkAppRouteConfigInterfaceProxy
MagentoBackendAppRequestPathInfoProcessorProxy
MagentoFrameworkLoggerMonolog
MagentoFrameworkLoggerHandlerSystem
MagentoFrameworkFilesystemDriverFile
MagentoFrameworkLoggerHandlerException
MagentoFrameworkLoggerHandlerDebug
MagentoFrameworkCacheFrontendAdapterZend
MagentoFrameworkCacheFrontendDecoratorTagScope
MagentoFrameworkCacheFrontendDecoratorLogger
MagentoFrameworkAppCacheTypeAccessProxy
MagentoFrameworkAppCacheState
MagentoFrameworkAppDeploymentConfigWriter
MagentoFrameworkAppDeploymentConfigReader
MagentoFrameworkConfigFileConfigFilePool
MagentoFrameworkConfigScope
MagentoFrameworkAppAreaListProxy
MagentoFrameworkInterceptionConfigConfig
MagentoFrameworkObjectManagerConfigReaderDomProxy
MagentoFrameworkConfigScope