[IMP] Cleanup and refactoring of exception handling

Unify and refactor exception handling in framework and addons.

The generic `except_osv` is now deprecated, and replaced by more specialized exception subtypes:
 - `UserError` (renamed from Warning, as it conflicts with the built-in `Warning`) raised when a non-technical error occurs during a business operation. It could be a missing information in the data provided by the user, or a misconfiguration.
 - `AccessError`: raised when any operation is denied because the user conducting it does not have the required access rights.
 - `AccessDenied`: raised when an operation that requires authenticated access is attempted via an unauthenticated request.
 - `MissingError`: raised when an operation is attempted on a record that does not exist.
 - `ValidationError`: raised when an operation violates a SQL or Python constraint.
 - All other exceptions are internal errors due to a system problem or bug, and raised untouched to the client-side, which should display a traceback.

All exceptions take a single message argument.

The `test_exceptions` module has been updated to showcase both new and old (deprecated) exceptions.

A great many old `except_osv` had a useless title with "Error!" or "Warning", those have been removed, as this is handled by the client-side widget that displays the messages.

This commit introduces a more consistent policy for logging errors and warnings:
 - All messages that do not require administrator attention should be logged at INFO level or lower. This includes all errors that are notified to the user in a friendly manner, even for access right problems or validation errors during business operations.
 - All messages that indicate a likely misconfiguration or malicious use by the users should be logged at WARNING level, as they typically require administrator attention.
 - All other unhandled internal errors cannot typically be handled by the user and should be logged at ERROR or higher level, as they require immediate administrator attention.

1 files changed, 37 insertions, 10 deletions

diff --git a/openerp/exceptions.py b/openerp/exceptions.py
index 7948b8a0fc1..58e57913272 100644
--- a/openerp/exceptions.py
+++ b/openerp/exceptions.py
@@ -28,15 +28,32 @@ treated as a 'Server error'.
 If you consider introducing new exceptions, check out the test_exceptions addon.
 """
 
+from inspect import currentframe
+import logging
+from tools.func import frame_codeinfo
+
+_logger = logging.getLogger(__name__)
+
+
 # kept for backward compatibility
 class except_orm(Exception):
-    def __init__(self, name, value):
+    def __init__(self, name, value=None):
+        if type(self) == except_orm:
+            caller = frame_codeinfo(currentframe(), 1)
+            _logger.warn('except_orm is deprecated. Please use specific exceptions like UserError or AccessError. Caller: %s:%s', *caller)
         self.name = name
         self.value = value
         self.args = (name, value)
 
-class Warning(Exception):
-    pass
+
+class UserError(except_orm):
+    def __init__(self, msg):
+        super(UserError, self).__init__(msg)
+
+
+# deprecated due to collision with builtins, kept for compatibility
+Warning = UserError
+
 
 class RedirectWarning(Exception):
     """ Warning with a possibility to redirect the user instead of simply
@@ -48,25 +65,35 @@ class RedirectWarning(Exception):
           the redirection.
     """
 
+
 class AccessDenied(Exception):
-    """ Login/password error. No message, no traceback. """
+    """ Login/password error. No message, no traceback.
+    Example: When you try to log with a wrong password."""
     def __init__(self):
-        super(AccessDenied, self).__init__('Access denied.')
+        super(AccessDenied, self).__init__('Access denied')
         self.traceback = ('', '', '')
 
+
 class AccessError(except_orm):
-    """ Access rights error. """
+    """ Access rights error.
+    Example: When you try to read a record that you are not allowed to."""
     def __init__(self, msg):
-        super(AccessError, self).__init__('AccessError', msg)
+        super(AccessError, self).__init__(msg)
+
 
 class MissingError(except_orm):
-    """ Missing record(s). """
+    """ Missing record(s).
+    Example: When you try to write on a deleted record."""
     def __init__(self, msg):
-        super(MissingError, self).__init__('MissingError', msg)
+        super(MissingError, self).__init__(msg)
+
 
 class ValidationError(except_orm):
+    """ Violation of python constraints
+    Example: When you try to create a new user with a login which already exist in the db."""
     def __init__(self, msg):
-        super(ValidationError, self).__init__('ValidateError', msg)
+        super(ValidationError, self).__init__(msg)
+
 
 class DeferredException(Exception):
     """ Exception object holding a traceback for asynchronous reporting.