Import Error - Pydev Eclipse
For that to work you need to have init.py under 'project_dir', 'dira' and 'dirb' and then you need to set as a source folder the directory which is the parent of the 'project_dir' (and not the project_dir itself) -- and no other directories should be set as source folders.
I.e.: the source folder is the directory added to the PYTHONPATH (so, for importing 'project_dir', its parent must be in the PYTHONPATH).
Note: You may have to remove the project from Eclipse/PyDev and recreate it a level before for this to work depending on how you created it the first time.
I have co'd existing code from an SVN repo that uses full imports - by which I mean:
-->projectdir
-------->dira
-------------->a1.py
-------------->a2.py
-------->dirb
-------------->b1.py
Suppose a1.py imports a method from a2.py:
Normally I would simply write: 

from a2 import xyz

Here they have written it as:

from project_dir.dira.a2 import xyz

How do I make eclipse recogonize these imports? 
Basically I want to be able to Ctrl+click and Open Declaration. I need to browse through this massive project and I simply cannot do so until this works.
PS: 

I have tried adding the projectdir to the PYTHONPATH
I have tried adding each and every sub-directory to PYTHONPATH
I have an init in every folder -_-