Doctrine Collections: ManyToMany, Forms & other Complex Relations

*Tip This course is built on Symfony 3**, but most of the concepts apply just fine to newer versions of Symfony.

With the basic of Doctrine relations behind us, it's time to dive deeper and get our hands dirty with some real-world, but complex collections. Honestly, this is the hardest part of Doctrine: so let's get it right:

• Creating ManyToMany associations
• Querying on ManyToMany relations
• Mapping the inverse (collection) side of a relation
• (bonus) Using DoctrineExtension for clean URL slugs
• Keeping the owning & inverse sides in-sync
• Using orphanRemoval to delete items in a collection
• Using cascade to save items in a collection
• Counting collections in the EXTRA_LAZY way
• Rendering relationship data from both sides
• Filtering collections efficiently with Criteria (mind will be blown)
• Dealing with complex collection forms
• Adding "extra" data to the "join table"

Doctrine relationships take a little bit more work to get setup. So let's master this stuff, setup our relationships to win, and get back to work.