But I want to be expert .Not just someone who knows how to make settings in admin panel. Lots of books are small one.i want better resource I guess spanning over 1000 pages like java complete reference book.I dont have money (8 lakhs indian rupees) to spend on expensive vids on official site.
I would suggest that you start with the basics, which you already can find in small books like "Magento PHP Developer's Guide" or similar.
And then, besides of a running Magento installation and a powerful IDE (I prefer PhpStorm), you need a lot of time for hands on.
Try to dig deep into the core of Magento, the official and free study guide is a good way to start.
And last but not least, code, code, code, code......
It took me at least more than a year working with Magento until I was able to pass the Magento Certified Developer exam.
Learning Magento could be initially intimidating, so you will have to be consistent and persistent in your efforts to study. There are lots of vidoes on youtube that introduce various aspects of development in Magento, I suggest you spend sometime to watch a lot of them. This will make you familiar with how things are done and what to expect.
I also suggest taking some courses on udemy, these worked for me:
And finally, you need to practise. You need to build different extensions to build your confidence.
The best examples of code are in the core Magento modules (located in
vendor/magento directory), so often spend time understanding how it works.