Fixed #17300 -- Prevented createcachetable from crashing when the cac…

…he table already exists. Thanks Claude Paroz.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17363 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management/commands/createcachetable.py

@@ -3,6 +3,7 @@
 from django.core.cache.backends.db import BaseDatabaseCache
 from django.core.management.base import LabelCommand
 from django.db import connections, router, transaction, models, DEFAULT_DB_ALIAS
+from django.db.utils import DatabaseError
 
 class Command(LabelCommand):
     help = "Creates the table needed to use the SQL cache backend."
@@ -51,7 +52,14 @@ def handle_label(self, tablename, **options):
             full_statement.append('    %s%s' % (line, i < len(table_output)-1 and ',' or ''))
         full_statement.append(');')
         curs = connection.cursor()
-        curs.execute("\n".join(full_statement))
-        for statement in index_output:
-            curs.execute(statement)
-        transaction.commit_unless_managed(using=db)
+        try:
+            curs.execute("\n".join(full_statement))
+        except DatabaseError, e:
+            self.stderr.write(
+                self.style.ERROR("Cache table '%s' could not be created.\nThe error was: %s.\n" %
+                    (tablename, e)))
+            transaction.rollback_unless_managed(using=db)
+        else:
+            for statement in index_output:
+                curs.execute(statement)
+            transaction.commit_unless_managed(using=db)

tests/regressiontests/cache/tests.py

@@ -7,6 +7,7 @@
 import hashlib
 import os
 import re
+import StringIO
 import tempfile
 import time
 import warnings
@@ -817,6 +818,11 @@ def test_old_initialization(self):
         self.cache = get_cache('db://%s?max_entries=30&cull_frequency=0' % self._table_name)
         self.perform_cull_test(50, 18)
 
+    def test_second_call_doesnt_crash(self):
+        err = StringIO.StringIO()
+        management.call_command('createcachetable', self._table_name, verbosity=0, interactive=False, stderr=err)
+        self.assertTrue("Cache table 'test cache table' could not be created" in err.getvalue())
+
 
 DBCacheWithTimeZoneTests = override_settings(USE_TZ=True)(DBCacheTests)