While developing new modules I face weird behaviours from time to time.

It seems that when something is not properly coded is quite easy to leave "stuff" on database or somewhere else, so you still see the old modules in the list of local modules even when they have been removed from the module director, the server restarted and the module list updated.

It is actually really annoying and after 8 months working intensively with Odoo I still find myself more time fixing these kind of issues in Odoo than doing actual work.

This time I am getting this error:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 537, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 574, in dispatch
    result = self._call_function(**self.params)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 310, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/service/model.py", line 113, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 307, in checked_call
    return self.endpoint(*a, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 803, in __call__
    return self.method(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/http.py", line 403, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/web/controllers/main.py", line 948, in call_button
    action = self._call_kw(model, method, args, {})
  File "/usr/lib/python2.7/dist-packages/openerp/addons/web/controllers/main.py", line 936, in _call_kw
    return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 241, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/module/module.py", line 446, in button_immediate_install
    return self._button_immediate_function(cr, uid, ids, self.button_install, context=context)
  File "/usr/lib/python2.7/dist-packages/openerp/api.py", line 241, in wrapper
    return old_api(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/openerp/addons/base/module/module.py", line 494, in _button_immediate_function
    registry = openerp.modules.registry.RegistryManager.new(cr.dbname, update_module=True)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/registry.py", line 370, in new
    openerp.modules.load_modules(registry._db, force_demo, status, update_module)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/loading.py", line 355, in load_modules
    loaded_modules, update_module)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/loading.py", line 255, in load_marked_modules
    loaded, processed = load_module_graph(cr, graph, progressdict, report=report, skip_modules=loaded_modules, perform_checks=perform_checks)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/loading.py", line 152, in load_module_graph
    models = registry.load(cr, package)
  File "/usr/lib/python2.7/dist-packages/openerp/modules/registry.py", line 163, in load
    model = cls._build_model(self, cr)
  File "/usr/lib/python2.7/dist-packages/openerp/models.py", line 596, in _build_model
    original_module = pool[name]._original_module if name in parents else cls._module
  File "/usr/lib/python2.7/dist-packages/openerp/modules/registry.py", line 102, in __getitem__
    return self.models[model_name]
KeyError: 'account_invoice'

The module I am trying to write is coded now in "delete_invoice" folder:

# cat delete_invoice.py

# -*- coding: utf-8 -*-
from openerp import models, fields, api

# DESCRIPTION:
# Class DeleteInvoices allows invoice deletion
# NOTES:
# account_cancel is needed and diaries need

class delete_invoice ( models.Model ):
        _inherit = 'account.invoice'

        @api.multi
        def unlink(self):
                for invoice in self:
                        if invoice.state not in ('draft', 'cancel'):
                                raise Warning(_('You cannot delete an invoice which is not draft or cancelled. You should refund it instead.'))
                        # elif invoice.internal_number:
                        #    raise Warning(_('You cannot delete an invoice after it has been validated (and received a number).  You can set it back to "Draft" state and modify its content, then re-confirm it.'))
                return super(delete_invoice, self).unlink()

# cat __init__.py
from . import delete_invoice

# cat __openerp__.py
{
        'name':         'Allow delete invoice',
        'description':  'This module allows to delete invoices once they have been cancelled',
        'author':       'E.M.',
        'depends':      ['account', 'account_cancel'],
        'data':         [],
}

Still wondering why I see "delete_invoices" and "delete_invoices2" modules in the list, which where the former names of this module.

Any tips on how to clean up failed module installations or fully remove registered old modules?