Added back-end error

Author: joachimmetz

tests/database.py

@@ -5,9 +5,8 @@
 import os
 import unittest
 
-import sqlite3
-
 from winevtrc import database
+from winevtrc import errors
 from winevtrc import resource_file
 from winevtrc import resources
 
@@ -82,7 +81,7 @@ def testGetValues(self):
     generator = database_file.GetValues(
         [u'bogus'], [u'name', u'value'], u'')
 
-    with self.assertRaises(sqlite3.OperationalError):
+    with self.assertRaises(errors.BackendError):
       next(generator)
 
     database_file.Close()
@@ -328,7 +327,7 @@ def testGetMessages(self):
 
     generator = database_reader.GetMessages(u'0x00000413', u'1.0.0.0')
 
-    with self.assertRaises(sqlite3.OperationalError):
+    with self.assertRaises(errors.BackendError):
       list(generator)
 
     database_reader.Close()
@@ -344,7 +343,7 @@ def testGetStringTables(self):
     generator = database_reader.GetStringTables()
 
     # TODO: string tables currently not written.
-    with self.assertRaises(sqlite3.OperationalError):
+    with self.assertRaises(errors.BackendError):
       list(generator)
 
     database_reader.Close()
@@ -360,7 +359,7 @@ def testGetStrings(self):
     generator = database_reader.GetStrings(u'0x00000409', u'1.0.0.0')
 
     # TODO: string tables currently not written.
-    with self.assertRaises(sqlite3.OperationalError):
+    with self.assertRaises(errors.BackendError):
       list(generator)
 
     database_reader.Close()

winevtrc/database.py

@@ -11,6 +11,7 @@
   import sqlite3
 
 from winevtrc import definitions
+from winevtrc import errors
 from winevtrc import py2to3
 from winevtrc import resources
 
@@ -56,6 +57,7 @@ def CreateTable(self, table_name, column_definitions):
       column_definitions (list[str]): column definitions.
 
     Raises:
+      BackendError: if the database back-end raises an exception.
       IOError: if the database is not opened or
           if the database is in read-only mode.
     """
@@ -68,7 +70,10 @@ def CreateTable(self, table_name, column_definitions):
     sql_query = u'CREATE TABLE {0:s} ( {1:s} )'.format(
         table_name, u', '.join(column_definitions))
 
-    self._cursor.execute(sql_query)
+    try:
+      self._cursor.execute(sql_query)
+    except sqlite3.OperationalError as exception:
+      raise errors.BackendError(exception)
 
   def GetValues(self, table_names, column_names, condition):
     """Retrieves values from a table.
@@ -82,6 +87,7 @@ def GetValues(self, table_names, column_names, condition):
       generator: values generator.
 
     Raises:
+      BackendError: if the database back-end raises an exception.
       IOError: if the database is not opened.
     """
     def _GetValues(cursor, table_names, column_names, condition):
@@ -102,7 +108,10 @@ def _GetValues(cursor, table_names, column_names, condition):
       sql_query = u'SELECT {1:s} FROM {0:s}{2:s}'.format(
           u', '.join(table_names), u', '.join(column_names), condition)
 
-      cursor.execute(sql_query)
+      try:
+        cursor.execute(sql_query)
+      except sqlite3.OperationalError as exception:
+        raise errors.BackendError(exception)
 
       for row in cursor:
         values = {}
@@ -126,18 +135,25 @@ def HasTable(self, table_name):
       bool: True if the table exists, false otheriwse.
 
     Raises:
+      BackendError: if the database back-end raises an exception.
       IOError: if the database is not opened.
     """
     if not self._connection:
       raise IOError(u'Cannot determine if table exists database not opened.')
 
     sql_query = self._HAS_TABLE_QUERY.format(table_name)
 
-    self._cursor.execute(sql_query)
-    if self._cursor.fetchone():
-      has_table = True
-    else:
-      has_table = False
+    try:
+      self._cursor.execute(sql_query)
+
+      if self._cursor.fetchone():
+        has_table = True
+      else:
+        has_table = False
+
+    except sqlite3.OperationalError as exception:
+      raise errors.BackendError(exception)
+
     return has_table
 
   def InsertValues(self, table_name, column_names, values):
@@ -149,6 +165,7 @@ def InsertValues(self, table_name, column_names, values):
       values (list[str]): values formatted as a string.
 
     Raises:
+      BackendError: if the database back-end raises an exception.
       IOError: if the database is not opened or
           if the database is in read-only mode or
           if an unsupported value type is encountered.
@@ -181,7 +198,10 @@ def InsertValues(self, table_name, column_names, values):
     sql_query = u'INSERT INTO {0:s} ( {1:s} ) VALUES ( {2:s} )'.format(
         table_name, u', '.join(column_names), u', '.join(sql_values))
 
-    self._cursor.execute(sql_query)
+    try:
+      self._cursor.execute(sql_query)
+    except sqlite3.OperationalError as exception:
+      raise errors.BackendError(exception)
 
   def Open(self, filename, read_only=False):
     """Opens the database file.
@@ -196,6 +216,7 @@ def Open(self, filename, read_only=False):
       bool: True if successful or False if not.
 
     Raises:
+      BackendError: if the database back-end raises an exception.
       IOError: if the database is already opened.
     """
     if self._connection:
@@ -208,7 +229,11 @@ def Open(self, filename, read_only=False):
     if not self._connection:
       return False
 
-    self._cursor = self._connection.cursor()
+    try:
+      self._cursor = self._connection.cursor()
+    except sqlite3.OperationalError as exception:
+      raise errors.BackendError(exception)
+
     if not self._cursor:
       return False
 

winevtrc/errors.py

@@ -0,0 +1,10 @@
+# -*- coding: utf-8 -*-
+"""The error objects."""
+
+
+class Error(Exception):
+  """The error interface."""
+
+
+class BackendError(Error):
+  """Error that is raised for database back-end exceptions."""