How to implement form in Symfony2 for tree structure?

Question

symfony

Rather, it is not the implementation of the form itself that is of interest (everything is simple there), but its processing, given that elements can be deleted, changed and moved.

Answer 1

An example of forms can be viewed/examined here:
github.com/beberlei/AcmePizzaBundle
There is no tree, but there is an addition/removal of elements. Moving is the same change (hidden field). In general, for starters, it would be nice to learn about the prototype attribute and how to deal with it.
However, I wouldn't recommend using Symfony Forms for this task (or any huge form in general) unless validation is required. Current forms slow down, and source codes are difficult to debug.

Answer 2

When it comes to nested collections, here is a proven recipe.