This is not an official guide, it's only a compilation of links extracted from the documentation based on the Symfony Certification page topics.
Even if you have no plans to take the Symfony certification exam, this list of resources may help you better understand the Symfony framework.
Feel free to fork and send a PR.
- Object Oriented Programming
http://www.php.net/manual/en/oop5.intro.php - Namespaces
http://www.php.net/manual/en/language.namespaces.php
https://knpuniversity.com/screencast/php-namespaces-in-120-seconds/namespaces - Interfaces
http://www.php.net/manual/en/language.oop5.interfaces.php - Anonymous functions and closures
http://www.php.net/manual/en/functions.anonymous.php - Abstract classes
http://www.php.net/manual/en/language.oop5.abstract.php
- Client / Server interaction
http://symfony.com/doc/2.3/book/http_fundamentals.html - HTTP request
http://symfony.com/doc/2.3/components/http_foundation/introduction.html#request - HTTP response
http://symfony.com/doc/2.3/components/http_foundation/introduction.html#response - Status codes
http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
- Standard edition of Symfony2
http://symfony.com/distributions - Components
http://symfony.com/doc/2.3/components/index.html - Bundles
http://symfony.com/doc/2.3/cookbook/bundles/best_practices.html http://symfony.com/doc/2.3/quick_tour/the_architecture.html#understanding-the-bundle-system - Bridges
http://stackoverflow.com/questions/11888522/what-are-symfony-bridges-bundles-and-vendor?answertab=votes#tab-top - Configuration
http://symfony.com/doc/2.3/quick_tour/the_architecture.html#configuring-a-bundle
http://symfony.com/doc/2.3/cookbook/configuration/index.html http://symfony.com/doc/2.3/components/config/index.html http://symfony.com/doc/2.3/cookbook/bundles/best_practices.html#configuration
http://symfony.com/doc/2.3/cookbook/bundles/extension.html
Code organization
http://symfony.com/doc/2.3/quick_tour/the_architecture.html#understanding-the-directory-structure - Request handling
http://symfony.com/doc/2.3/book/http_fundamentals.html#the-journey-from-the-request-to-the-response
-
Naming conventions
http://symfony.com/doc/2.3/contributing/code/standards.html#naming-conventions -
Coding standards
http://symfony.com/doc/2.3/contributing/code/standards.html -
Integration of third-party libraries
http://symfony.com/doc/2.3/cookbook/bundles/installation.html -
Composer packages handling
http://symfony.com/doc/2.3/book/installation.html https://knpuniversity.com/screencast/composer -
Development best practices
-
Overload the framework
http://symfony.com/doc/2.3/cookbook/bundles/override.html
- Naming conventions
http://symfony.com/doc/2.3/cookbook/bundles/best_practices.html#bundle-name - Code organization
http://symfony.com/doc/2.3/cookbook/bundles/best_practices.html#directory-structure - The controllers
http://symfony.com/doc/2.3/cookbook/bundles/best_practices.html#controllers http://symfony.com/doc/2.3/cookbook/controller/index.html http://symfony.com/doc/2.3/book/controller.html - The views
http://symfony.com/doc/2.3/quick_tour/the_view.html - The resources
- Naming conventions
http://symfony.com/doc/2.3/book/routing.html#controller-string-syntax - Get the request
http://symfony.com/doc/2.3/book/controller.html#requests-controller-response-lifecycle http://symfony.com/doc/2.3/components/http_foundation/introduction.html#request - Generate the response
http://symfony.com/doc/2.3/book/controller.html#requests-controller-response-lifecycle http://symfony.com/doc/2.3/components/http_foundation/introduction.html#response - The cookies
http://symfony.com/doc/2.3/components/http_foundation/introduction.html#setting-cookies - The session
http://symfony.com/doc/2.3/book/controller.html#managing-the-session http://symfony.com/doc/2.3/components/http_foundation/sessions.html - Session flashbag
http://symfony.com/doc/2.3/book/controller.html#flash-messages http://symfony.com/doc/2.3/components/http_foundation/sessions.html#flash-messages - Redirects
http://symfony.com/doc/2.3/book/controller.html#redirecting - Internal redirects
http://symfony.com/doc/2.3/book/controller.html#forwarding - Generate 404 pages
http://symfony.com/doc/2.3/book/controller.html#managing-errors-and-404-pages http://symfony.com/doc/2.3/cookbook/controller/error_pages.html#customizing-the-404-page-and-other-error-pages
- Configuration (YAML / XML / PHP & annotations)
http://symfony.com/doc/2.3/book/routing.html#basic-route-configuration - Restrict URL parameters
http://symfony.com/doc/2.3/book/routing.html#routing-with-placeholders - Set default values to URL parameters
http://symfony.com/doc/2.3/book/routing.html#required-and-optional-placeholders - Generate URL parameters
http://symfony.com/doc/2.3/book/routing.html#generating-urls http://symfony.com/doc/2.3/book/routing.html#generating-urls-with-query-strings - Trigger redirections
http://symfony.com/doc/2.3/cmf/components/routing/dynamic.html#redirections http://symfony.com/doc/2.3/cookbook/routing/redirect_in_config.html
- Auto escape
http://twig.sensiolabs.org/doc/tags/autoescape.html http://symfony.com/doc/2.3/book/templating.html#output-escaping-in-twig - Template inheritance
http://twig.sensiolabs.org/doc/tags/extends.html http://twig.sensiolabs.org/doc/templates.html#template-inheritance http://symfony.com/doc/2.3/book/templating.html#template-inheritance-and-layouts - Global functions
http://twig.sensiolabs.org/doc/functions/index.html - Filters
http://twig.sensiolabs.org/doc/filters/index.html - Template includes
http://twig.sensiolabs.org/doc/tags/include.html - Control statements (loops and conditions)
http://twig.sensiolabs.org/doc/tags/for.html http://twig.sensiolabs.org/doc/templates.html#control-structure - Urls generation
http://symfony.com/doc/2.3/book/routing.html#generating-urls-from-a-template http://symfony.com/doc/2.3/book/templating.html#linking-to-pages - Call a controller from a view
http://symfony.com/doc/2.3/book/templating.html#embedding-controllers - Translations
http://symfony.com/doc/2.3/book/translation.html#translations-in-templates
- Create forms
http://symfony.com/doc/2.3/book/forms.html#creating-a-simple-form - Handling forms
http://symfony.com/doc/2.3/book/forms.html#handling-form-submissions - Form types
http://symfony.com/doc/2.3/book/forms.html#creating-form-classes http://symfony.com/doc/2.3/book/forms.html#built-in-field-types - Render forms with Twig
http://symfony.com/doc/2.3/book/forms.html#rendering-a-form-in-a-template - Forms security (CSRF)
http://symfony.com/doc/2.3/book/forms.html#csrf-protection
- Validate a PHP object
http://symfony.com/doc/2.3/book/validation.html#the-basics-of-validation - Native validation rules
http://symfony.com/doc/2.3/book/validation.html#constraints - Validation scopes
- Validation groups
http://symfony.com/doc/2.3/book/validation.html#validation-groups
- The Service container
http://symfony.com/doc/2.3/book/service_container.html - Global configuration parameters http://symfony.com/doc/2.3/components/dependency_injection/parameters.html http://symfony.com/doc/2.3/components/dependency_injection/introduction.html#setting-up-the-container-with-configuration-files
- Symfony2 services
http://symfony.com/doc/2.3/book/service_container.html#what-is-a-service - Register new services
http://symfony.com/doc/2.3/book/service_container.html#creating-configuring-services-in-the-container - Tags
http://symfony.com/doc/2.3/book/service_container.html#tags http://symfony.com/doc/2.3/reference/dic_tags.html - Semantic configuration
http://symfony.com/doc/2.3/cookbook/bundles/extension.html
- Authentication
http://symfony.com/doc/2.3/components/security/authentication.html http://symfony.com/doc/2.3/book/security.html#how-security-works-authentication-and-authorization - Authorization
http://symfony.com/doc/2.3/components/security/authorization.html http://symfony.com/doc/2.3/book/security.html#authorization - Configuration
http://symfony.com/doc/2.3/reference/configuration/security.html - Providers
http://symfony.com/doc/2.3/book/security.html#where-do-users-come-from-user-providers - Firewalls
http://symfony.com/doc/2.3/book/security.html#firewalls-authentication http://symfony.com/doc/2.3/components/security/firewall.html - Users
http://symfony.com/doc/2.3/book/security.html#users - Encoders
http://symfony.com/doc/2.3/book/security.html#encoding-the-user-s-password - Roles
http://symfony.com/doc/2.3/components/security/authorization.html#roles http://symfony.com/doc/2.3/book/security.html#roles - Access Control Rules
http://symfony.com/doc/2.3/book/security.html#access-control-in-templates http://symfony.com/doc/2.3/book/security.html#access-control-in-controllers
- Cache types (browser, proxies and reverse proxies)
- http://symfony.com/doc/2.3/book/http_cache.html#types-of-caches
- Expiration (Expires, Cache-control)
http://symfony.com/doc/2.3/book/http_cache.html#expiration - Validation (ETag, Last-Modified)
- http://symfony.com/doc/2.3/book/http_cache.html#validation
- Client cache
- Server cache
- Edge Side Includes
http://symfony.com/doc/2.3/book/http_cache.html#using-edge-side-includes
- Symfony2 commands
http://symfony.com/doc/2.3/components/console/usage.html#built-in-commands - Custom commands
http://symfony.com/doc/2.3/components/console/introduction.html#creating-a-basic-command
http://symfony.com/doc/2.3/cookbook/console/console_command.html - Configuration
- Options and arguments
http://symfony.com/doc/2.3/components/console/introduction.html#using-command-options
http://symfony.com/doc/2.3/components/console/introduction.html#using-command-arguments - Read the entry and write the output
- Unit tests with PHPUnit
http://symfony.com/doc/2.3/book/testing.html#the-phpunit-testing-framework - Functional tests
http://symfony.com/doc/2.3/book/testing.html#functional-tests - The Client object
http://symfony.com/doc/2.3/book/testing.html#working-with-the-test-client - The Crawler object
http://symfony.com/doc/2.3/book/testing.html#the-crawler - The Profile object
http://symfony.com/doc/2.3/book/testing.html#accessing-the-profiler-data http://symfony.com/doc/2.3/cookbook/testing/profiling.html - Access framework objects
http://symfony.com/doc/2.3/book/testing.html#accessing-internal-objects http://symfony.com/doc/2.3/book/testing.html#accessing-the-container - Configure the client
- Introspect the request and response
http://symfony.com/doc/2.3/book/testing.html#accessing-internal-objects
- Error handling
http://symfony.com/doc/2.3/cookbook/controller/error_pages.html - Debug the code
http://symfony.com/doc/2.3/cookbook/debugging.html
- The Symfony Book
http://symfony.com/doc/2.3/book/index.html - The Symfony Cookbook
http://symfony.com/doc/2.3/cookbook/index.html - The Symfony Book Spanish
http://librosweb.es/symfony_2_3/
The Symfony Glossary
http://symfony.com/doc/2.3/glossary.html
- Desarrollo web ágil con Symfony2 Spanish
http://symfony.es/libro/ - A year with Symfony
https://leanpub.com/a-year-with-symfony - Un año con Symfony Spanish
https://leanpub.com/un-ano-con-symfony - Extending Symfony2 Web Application Framework
http://www.packtpub.com/extending-symfony-2-web-application-framework/book - Testing para Aplicaciones Symfony2 Spanish
https://leanpub.com/testingsymfony2 - Symfony Enterprise Applications https://leanpub.com/symfony-enterprise-applications
- Extending Symfony2 Web Application Framework https://www.packtpub.com/web-development/extending-symfony2-web-application-framework
- KNP University - PHP and Symfony Tutorial Screencasts
http://knpuniversity.com/ - SymfonyBricks
https://symfonybricks.com/ - Symfony2 cheat sheet
http://www.symfony2cheatsheet.com/ - Symfony2 Tutorials
http://www.screenfony.com/ - Symfony2 deployment checklist
http://www.symfony2-checklist.com/ - A Symfony Console CLI tool to train on Symfony certification
https://github.com/certificationy/certificationy-cli - A Symfony Web Platform tool to train on Symfony certification
http://www.certificationy.com/