Opened 10 years ago

Closed 9 years ago

#2482 closed enhancement (fixed)

[patch] Add optional flat values() to QuerySet

Reported by: mccutchen@… Owned by: Daniel Poelzleithner
Component: Database layer (models, ORM) Version:
Severity: normal Keywords: sprintdec01 qs-rf-fixed
Cc: mccutchen@…, gary.wilson@… Triage Stage: Accepted
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: yes
Easy pickings: UI/UX:

Description

The attached patch adds a keyword argument, 'flat', to the QuerySet.values() method, which causes it to return a flattened list of values rather than a list of dictionaries.

See discussion here:
http://groups.google.com/group/django-developers/browse_thread/thread/0b1897d4d5dd7277/1ed627b92f3e56c9#1ed627b92f3e56c9

Attachments (2)

values-flat.diff (3.1 KB) - added by mccutchen@… 10 years ago.
Diff against trunk revision 3522
valuelist.diff (4.0 KB) - added by mccutchen@… 10 years ago.
Patch which implements valuelist() method

Download all attachments as: .zip

Change History (18)

Changed 10 years ago by mccutchen@…

Attachment: values-flat.diff added

Diff against trunk revision 3522

comment:1 Changed 10 years ago by anonymous

This is my first attempt to contribute code to Django. I added a couple of tests to the lookup tests, I hope they are appropriate.

comment:2 Changed 10 years ago by mccutchen@…

An alternative approach, as suggested by Gary Wilson in the thread linked above, is to add a separate method to QuerySet objects:

Maybe .flatvalues("id", "name") or .valuelist("id", "name")

If that is the preferred route, I would vote for 'valuelist' as the name of the method.

comment:3 Changed 10 years ago by jim@…

I'd like to suggest .items("id", "name"). With no parameters, it would would default to all fields in creation order.

This maps up nicely with dictionary object's "items" method.

comment:4 Changed 10 years ago by anonymous

I'd like to suggest .items("id", "name"). With no parameters, it would would default to all fields in creation order.

This maps up nicely with dictionary object's "items" method.

I'm not so sure about this. The dictionary object's "items" method returns tuples of (key, value) in a dictionary, whereas the whole point of this flag/new method is to remove the keys altogether, when you just want some values. So naming the same as the dictionary method would be misleading.

comment:5 Changed 10 years ago by Adrian Holovaty

Thanks for the patch! Could you rewrite it (and the unit tests) to be a separate method called .valuelist?

comment:6 Changed 10 years ago by mccutchen@…

A new patch is attached, valuelist.diff, which creates a new method called valuelist(). This patch adds a new class, ValueListQuerySet, which inherits from ValuesQuerySet. I factored some of the logic out of ValuesQueryset's iterator() method into a get_columns() method and a get_field_names() method, so that the same logic could be used in the ValueListQuerySet object.

There are two doctests added, and they both pass.

I hope this is an appropriate solution.

P.S. The last diff I attached could not be previewed by Trac for some reason. I'm about to attach a new one. If it doesn't work either, does anyone have any idea what I'm doing wrong?

Changed 10 years ago by mccutchen@…

Attachment: valuelist.diff added

Patch which implements valuelist() method

comment:7 Changed 10 years ago by Malcolm Tredinnick

Owner: changed from Adrian Holovaty to Malcolm Tredinnick

I'll merge this into the ongoing query rewrite.

comment:8 Changed 10 years ago by Gary Wilson <gary.wilson@…>

Cc: gary.wilson@… added

Thanks for the patch Will. I finally needed to get a list of ids the other day and was remembering about this. Sadly, it's not yet merged :(

comment:9 Changed 10 years ago by Chris Beaven

A good point is made here: http://groups-beta.google.com/group/django-developers/browse_thread/thread/22b44f4eafaf956a/1515cf99737ab589#1515cf99737ab589

I'd also prefer a way to ensure tuples are always returned.

comment:10 Changed 10 years ago by Michael Radziej <mir@…>

Triage Stage: UnreviewedDesign decision needed

This needs a decision on how to treat single-field lists, see thread in comment above.

comment:11 Changed 9 years ago by Daniel Poelzleithner

Keywords: sprintdec01 added
Owner: changed from nobody to Daniel Poelzleithner
Patch needs improvement: set

comment:12 Changed 9 years ago by Jacob

Triage Stage: Design decision neededAccepted

I'm not a huge fan of valuelist() since it smells a bit of creeping featurism, but since Adrian likes this I'll go ahead and mark it accepted.

comment:13 Changed 9 years ago by Chris Beaven

Keywords: qs-rf added

comment:14 Changed 9 years ago by Malcolm Tredinnick

(In [7149]) queryset-refactor: Added valuelist() method to querysets. Refs #2482.

comment:15 Changed 9 years ago by Malcolm Tredinnick

Keywords: qs-rf-fixed added; qs-rf removed

comment:16 Changed 9 years ago by Malcolm Tredinnick

Resolution: fixed
Status: newclosed

(In [7477]) Merged the queryset-refactor branch into trunk.

This is a big internal change, but mostly backwards compatible with existing
code. Also adds a couple of new features.

Fixed #245, #1050, #1656, #1801, #2076, #2091, #2150, #2253, #2306, #2400, #2430, #2482, #2496, #2676, #2737, #2874, #2902, #2939, #3037, #3141, #3288, #3440, #3592, #3739, #4088, #4260, #4289, #4306, #4358, #4464, #4510, #4858, #5012, #5020, #5261, #5295, #5321, #5324, #5325, #5555, #5707, #5796, #5817, #5987, #6018, #6074, #6088, #6154, #6177, #6180, #6203, #6658

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