What is the best way to put custom library or helper methods in symfony? I am using doctrine with my project. One place I consider to put is under
project_root/lib/vendor/MyClasses/But if I want to create a class or helper function which will use some core symfony/doctrine methods and return a result then how to do that and where should I put it? I want it to call from different modules to avoid code duplication.
As for the custom library part of the question, you might probably want to put your external library into the lib/vendor folder. Since symfony doesn't automatically load everything that's in there, you'll have to tell its autoloader to do so.
You can either extend your config/ProjectConfiguration.class.php (as described here) or (and this is the much simpler and cleaner way) you add them to your config/autoload.yml (you might have to create this one). For the latter option, this is a great place to start looking at.