I quickly ran into an issue that was tough to track down. After added the database code the form no longer submitted. After ripping out lots of code and not finding an answer I called it a night. The next day I figured out the problem was with MAMP not my code. If I disabled the file validation on the form everything worked fine.
This was the error I ran into
Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 32 bytes) in /Volumes/zend_framework/learnzf2/vendor/zendframework/zendframework/library/Zend/Stdlib/ErrorHandler.php on line 113
Not the most straight forward bug. Turns out the issue is the command line PHP server has a larger memory_limit size. It's 128M while MAMP is set to 32M. It overflowed after processing the file. After upping memory_limit to 128M and restarting the server everything worked fine.
The memory_limit var is stored in php.ini. It can be reached by using
File => Edit template => php => php 5.4
Find memory_limit and change it to 128M.