dumpdata should take option to output to named file

[murftone@…]

If the dumpdata management command could output to a named file, it would make it a lot easier to invoke dumpdata from other management commands via call_command.

[Simon Charette]

We could ​document you can achieve this by passing a file like object as the stdout kwarg of call_command.

with open('/tmp/call_command_output') as f:
    call_command('dumpdata', stdout=f)

This looks quite easy to me.

[Roman Gladkov]

added new optional parameter to dumpdata command, for save data to file

[Claude Paroz]

This ticket was accepted on the base that we should document the stdout usage of call_command, which is also useful for all other commands. Not to add another option to dumpdata.

[Roman Gladkov]

Ok. I'm sorry, I fixed this patch and added only documentation.

[Claude Paroz]

Thanks for your efforts. As the stdout option is valid for all commands, I'd rather add a paragraph (Output redirection) in the section ​https://docs.djangoproject.com/en/dev/ref/django-admin/#running-management-commands-from-your-code

Then you can just add a reference to it from the dumpdata section.

[Roman Gladkov]

I agree. That looks better.

[Claude Paroz]

After some thoughts, here's how I'd like to document it. I don't think it's worth adding the note to the dumpdata command section, as we should then specify it also for all other commands which output data. We can count on people trying to output data with a management command to look after the call_command section.

[Claude Paroz <claude@…>]

In b1ac329ba9bbcba90d8ced7e16909ed169b1d16e:

Fixed #19115 -- Documented stdout/stderr options for call_command

Thanks d1ffuz0r for helping with the patch.

[Claude Paroz <claude@…>]

In b8726179249ede88c988c13fd4b1077e49e8b151:

[1.5.x] Fixed #19115 -- Documented stdout/stderr options for call_command

Thanks d1ffuz0r for helping with the patch.
Backport of b1ac329ba from master.

[maa@…]

how do we use this ?
./manage dumpdata --stdout=file.json ?

[Baptiste Mispelon]

Replying to maa@…:

how do we use this ?
./manage dumpdata --stdout=file.json ?

This ticket tracker is not the best place to ask questions like this. You should use our support channels instead [1].

As for your question, since the command outputs its result, you can use your shell's output redirection feature:

./manage dumpdata > the_name_of_the_file.json

[1] https://code.djangoproject.com/wiki/TicketClosingReasons/UseSupportChannels