Inserting literal % sign in QuerySet.extra()

[Gergely Polonkai]

Hello,

I’d like to execute the following code:

Booking.objects.filter(start_ts__isnull = False, end_ts__isnull = False).extra(select = {'amount': "strftime('%s', end_ts) - strftime('%s', start_ts)"})

However, in the shell, I get the following error:

Traceback (most recent call last): File "<console>", line 1, in <module> File "/home/polesz/Projects/duckbook/venv/lib/python3.4/site-packages/django/db/models/query.py", line 835, in extra clone.query.add_extra(select, select_params, where, params, tables, order_by) File "/home/polesz/Projects/duckbook/venv/lib/python3.4/site-packages/django/db/models/sql/query.py", line 1744, in add_extra entry_params.append(next(param_iter)) StopIteration

I have tried doubling the percent signs (%%s) and escaping them with a backslash (\%s), but neither helped. I also looked at this answer[1], but that solution doesn’t work with QuerySet.extra() (or I just miss the point).

What is the correct way to solve this?

I also tried to use select_params like this:

Booking.objects.filter(start_ts__isnull = False, end_ts__isnull = False).extra(select = {'amount': "strftime('%s', end_ts) - strftime(%s, start_ts)"}, select_params = ['%s', '%s'])

but regardless the usage of quote signs, the resulting query has \'%s\', which gives an SQL error, of course.

Best,
Gergely

[1] http://stackoverflow.com/a/18143147/1305139

[Tim Graham]

This is fixed in Django 1.8. See the fifth item in https://docs.djangoproject.com/en/dev/releases/1.8/#models.

[Gergely Polonkai]

Great, thank you!

Although I'm more than willing to upgrade, I still wonder if this fix will be backported to 1.7…

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[Tim Graham]

No, it won't. See https://docs.djangoproject.com/en/dev/internals/release-process/#supported-versions for the guidelines on which changes are backported.