Stops caching queries with random subqueries.

cachalot/monkey_patch.py

@@ -26,7 +26,7 @@ from .cache import cachalot_caches
 from .settings import cachalot_settings
 from .utils import (
     _get_query_cache_key, _invalidate_tables,
-    _get_table_cache_keys, _get_tables_from_sql)
+    _get_table_cache_keys, _get_tables_from_sql, RandomQueryException)
 
 
 WRITE_COMPILERS = (SQLInsertCompiler, SQLUpdateCompiler, SQLDeleteCompiler)
@@ -84,18 +84,17 @@ def _patch_compiler(original):
     def inner(compiler, *args, **kwargs):
         execute_query_func = lambda: original(compiler, *args, **kwargs)
         if not cachalot_settings.CACHALOT_ENABLED \
-                or isinstance(compiler, WRITE_COMPILERS) \
-                or (not cachalot_settings.CACHALOT_CACHE_RANDOM
-                    and '?' in compiler.query.order_by):
+                or isinstance(compiler, WRITE_COMPILERS):
             return execute_query_func()
 
         try:
             cache_key = _get_query_cache_key(compiler)
-        except EmptyResultSet:
+            table_cache_keys = _get_table_cache_keys(compiler)
+        except (EmptyResultSet, RandomQueryException):
             return execute_query_func()
 
         return _get_result_or_execute_query(
-            execute_query_func, cache_key, _get_table_cache_keys(compiler))
+            execute_query_func, cache_key, table_cache_keys)
 
     inner.original = original
     return inner

cachalot/utils.py

@@ -18,6 +18,10 @@ from .settings import cachalot_settings
 from .signals import post_invalidation
 
 
+class RandomQueryException(Exception):
+    pass
+
+
 def get_query_cache_key(compiler):
     """
     Generates a cache key from a SQLCompiler.
@@ -88,8 +92,11 @@ def _find_subqueries(children):
 
 
 def _get_tables(query, db_alias):
+    if '?' in query.order_by and not cachalot_settings.CACHALOT_CACHE_RANDOM:
+        raise RandomQueryException
+
     tables = set(query.table_map)
-    tables.add(query.model._meta.db_table)
+    tables.add(query.get_meta().db_table)
     subquery_constraints = _find_subqueries(query.where.children
                                             + query.having.children)
     for subquery in subquery_constraints: