#29257: If creation of a db cursor fails, the resulting traceback is misleading
-------------------------------------+-------------------------------------
Reporter: Jerome | Owner: nobody
Leclanche |
Type: | Status: new
Uncategorized |
Component: Database | Version: 2.0
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 1
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
When a schema is out of sync (eg. running tests for a project where a
model has fields not present in the migration).
The creation of a cursor involves a sql query which includes all of the
field names. Creating that cursor will fail.
However, the exception is currently caught by a try/except which always
attempts to *close* the cursor. Closing the cursor is not try/excepted,
which results in that particular query failing and a traceback that looks
like "ERROR: cursor "_django_curs_140260213699904_6" does not exist".
Patch:
{{{
commit 7c7a1f53acbf7d94f0a9b360f973711a7c9fbfbd (HEAD ->
refs/heads/master)
Author: Jerome Leclanche <[email protected]>
Date: Tue Mar 20 09:57:26 2018 +0200
Raise outer exception when failing to close a cursor after an error
diff --git a/django/db/models/sql/compiler.py
b/django/db/models/sql/compiler.py
index 1fdbd156b6..f96be3c4ea 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -1051,10 +1051,15 @@ class SQLCompiler:
cursor = self.connection.cursor()
try:
cursor.execute(sql, params)
- except Exception:
+ except Exception as e:
# Might fail for server-side cursors (e.g. connection closed)
- cursor.close()
- raise
+ try:
+ cursor.close()
+ except Exception:
+ # If we got an error creating the cursor, then closing it
+ # will always fail. Raise the outer exception instead of
the
+ # obscure "cursor _django_curs_xxxx does not exist".
+ raise e from None
if result_type == CURSOR:
# Give the caller the cursor to process and close.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/29257>
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