represent tablesample.sampling as FunctionElement in all cases

Fixed regression where the :func:`_sql.tablesample` construct would fail to
be executable when constructed given a floating-point sampling value not
embedded within a SQL function.

Fixes: #6735
Change-Id: I557bcd4bdbffc4329ad69d5659ba99b1c8deb554

1 files changed, 6 insertions, 6 deletions

diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index 235c74ea7..42cb6e5ae 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -1970,18 +1970,18 @@ class TableSample(AliasedReturnsRows):
             sampling, name=name, seed=seed
         )
 
+    @util.preload_module("sqlalchemy.sql.functions")
     def _init(self, selectable, sampling, name=None, seed=None):
+        functions = util.preloaded.sql_functions
+        if not isinstance(sampling, functions.Function):
+            sampling = functions.func.system(sampling)
+
         self.sampling = sampling
         self.seed = seed
         super(TableSample, self)._init(selectable, name=name)
 
-    @util.preload_module("sqlalchemy.sql.functions")
     def _get_method(self):
-        functions = util.preloaded.sql_functions
-        if isinstance(self.sampling, functions.Function):
-            return self.sampling
-        else:
-            return functions.func.system(self.sampling)
+        return self.sampling
 
 
 class CTE(