id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30770	"annotating  TruncBase on ExpressionWrapper for date arithmetic, causes unnecessary  placeholder ""%s"" escaping to ""%%s"""	Jurgis Pralgauskis	nobody	"I tried:
{{{#!python
from django.db.models import F,  DateTimeField, ExpressionWrapper
from django.db.models.functions import Cast, Least, Greatest, Now, Coalesce, ExtractWeekDay, TruncDay
User.objects
   .annotate(trial_end=TruncDay(ExpressionWrapper(F('date_joined')+ timedelta(days=30), output_field=DateTimeField())))
   .values('id', 'date_joined', 'trial_end')[:3]
)
}}}

and got 
{{{
Traceback (most recent call last):
  File ""<input>"", line 3, in <module>
  File ""lib/python3.4/site-packages/django/db/models/query.py"", line 226, in __repr__
    data = list(self[:REPR_OUTPUT_SIZE + 1])
  File ""lib/python3.4/site-packages/django/db/models/query.py"", line 250, in __iter__
    self._fetch_all()
  File ""lib/python3.4/site-packages/django/db/models/query.py"", line 1118, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File ""lib/python3.4/site-packages/django/db/models/query.py"", line 106, in __iter__
    for row in compiler.results_iter():
  File ""lib/python3.4/site-packages/django/db/models/sql/compiler.py"", line 836, in results_iter
    results = self.execute_sql(MULTI)
  File ""lib/python3.4/site-packages/django/db/models/sql/compiler.py"", line 894, in execute_sql
    raise original_exception
  File ""lib/python3.4/site-packages/django/db/models/sql/compiler.py"", line 884, in execute_sql
    cursor.execute(sql, params)
  File ""lib/python3.4/site-packages/django/db/backends/utils.py"", line 80, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File ""lib/python3.4/site-packages/django/db/backends/utils.py"", line 65, in execute
    return self.cursor.execute(sql, params)
TypeError: not all arguments converted during string formatting
}}}


and

{{{#!python
 qs.query.sql_with_params()[0]
}}}

shows 

{{{#!sql
'SELECT ""ta_account"".""id"", ""ta_account"".""date_joined"", DATE_TRUNC(\'day\', (""ta_account"".""date_joined"" + %%s) AT TIME ZONE %s) AS ""trial_end"" FROM ""ta_account"" LIMIT 3'
}}}

notice **%%s** -- that causes problem.."	Bug	new	Database layer (models, ORM)	1.11	Normal		TruncBase, DateTime arithmetics,		Unreviewed	0	0	0	0	0	0