1 files changed, 77 insertions, 20 deletions
diff --git a/lib/extras.py b/lib/extras.py
index 2d26402..38ca17a 100644
--- a/lib/extras.py
+++ b/lib/extras.py
@@ -1168,11 +1168,15 @@ def execute_batch(cur, sql, argslist, page_size=100):
     Execute *sql* several times, against all parameters set (sequences or
     mappings) found in *argslist*.
 
-    The function is semantically similar to `~cursor.executemany()`, but has a
-    different implementation: Psycopg will join the statements into fewer
-    multi-statement commands, reducing the number of server roundtrips,
-    resulting in better performances. Every command contains at most
-    *page_size* statements.
+    The function is semantically similar to
+
+    .. parsed-literal::
+
+        *cur*\.\ `~cursor.executemany`\ (\ *sql*\ , *argslist*\ )
+
+    but has a different implementation: Psycopg will join the statements into
+    fewer multi-statement commands, each one containing at most *page_size*
+    statements, resulting in a reduced number of server roundtrips.
 
     """
     for page in _paginate(argslist, page_size=page_size):
@@ -1183,18 +1187,30 @@ def execute_batch(cur, sql, argslist, page_size=100):
 def execute_values(cur, sql, argslist, template=None, page_size=100):
     '''Execute a statement using :sql:`VALUES` with a sequence of parameters.
 
-    *sql* must contain a single ``%s`` placeholder, which will be replaced by a
-    `VALUES list`__.  Every statement will contain at most *page_size* sets of
-    arguments.
+    :param cur: the cursor to use to execute the query.
 
-    .. __: https://www.postgresql.org/docs/current/static/queries-values.html
+    :param sql: the query to execute. It must contain a single ``%s``
+        placeholder, which will be replaced by a `VALUES list`__.
+        Example: ``"INSERT INTO mytable (id, f1, f2) VALUES %s"``.
+
+    :param argslist: sequence of sequences or dictionaries with the arguments
+        to send to the query. The type and content must be consistent with
+        *template*.
 
-    *template* is the part merged to the arguments, so it should be compatible
-    with the content of *argslist* (it should contain the right number of
-    arguments if *argslist* is a sequence of sequences, or compatible names if
-    *argslist* is a sequence of mappings). If not specified, assume the
-    arguments are sequence and use a simple positional template (i.e.
-    ``(%s, %s, ...)``).
+    :param template: the snippet to merge to every item in *argslist* to
+        compose the query. If *argslist* items are sequences it should contain
+        positional placeholders (e.g. ``"(%s, %s, %s)"``, or ``"(%s, %s, 42)``"
+        if there are constants value...); If *argslist* is items are mapping
+        it should contain named placeholders (e.g. ``"(%(id)s, %(f1)s, 42)"``).
+        If not specified, assume the arguments are sequence and use a simple
+        positional template (i.e.  ``(%s, %s, ...)``), with the number of
+        placeholders sniffed by the first element in *argslist*.
+
+    :param page_size: maximum number of *argslist* items to include in every
+        statement. If there are more items the function will execute more than
+        one statement.
+
+    .. __: https://www.postgresql.org/docs/current/static/queries-values.html
 
     While :sql:`INSERT` is an obvious candidate for this function it is
     possible to use it with other statements, for example::
@@ -1216,10 +1232,51 @@ def execute_values(cur, sql, argslist, template=None, page_size=100):
         [(1, 20, 3), (4, 50, 6), (7, 8, 9)])
 
     '''
+    # we can't just use sql % vals because vals is bytes: if sql is bytes
+    # there will be some decoding error because of stupid codec used, and Py3
+    # doesn't implement % on bytes.
+    if not isinstance(sql, bytes):
+        sql = sql.encode(_ext.encodings[cur.connection.encoding])
+    pre, post = _split_sql(sql)
+
     for page in _paginate(argslist, page_size=page_size):
         if template is None:
-            template = '(%s)' % ','.join(['%s'] * len(page[0]))
-        values = b",".join(cur.mogrify(template, args) for args in page)
-        if isinstance(values, bytes):
-            values = values.decode(_ext.encodings[cur.connection.encoding])
-        cur.execute(sql % (values,))
+            template = b'(' + b','.join([b'%s'] * len(page[0])) + b')'
+        parts = pre[:]
+        for args in page:
+            parts.append(cur.mogrify(template, args))
+            parts.append(b',')
+        parts[-1:] = post
+        cur.execute(b''.join(parts))
+
+
+def _split_sql(sql):
+    """Split *sql* on a single ``%s`` placeholder.
+
+    Split on the %s, perform %% replacement and return pre, post lists of
+    snippets.
+    """
+    curr = pre = []
+    post = []
+    tokens = _re.split(br'(%.)', sql)
+    for token in tokens:
+        if len(token) != 2 or token[:1] != b'%':
+            curr.append(token)
+            continue
+
+        if token[1:] == b's':
+            if curr is pre:
+                curr = post
+            else:
+                raise ValueError(
+                    "the query contains more than one '%s' placeholder")
+        elif token[1:] == b'%':
+            curr.append(b'%')
+        else:
+            raise ValueError("unsupported format character: '%s'"
+                % token[1:].decode('ascii', 'replace'))
+
+    if curr is pre:
+        raise ValueError("the query doesn't contain any '%s' placeholder")
+
+    return pre, post