Re: [Django] #30222: documentation bug for base managers

2019-02-28 Thread Django 
#30222: documentation bug for base managers
---+--
 Reporter:  David Gudeman  |Owner:  nobody
 Type:  Bug|   Status:  closed
Component:  Documentation  |  Version:  2.1
 Severity:  Normal |   Resolution:  invalid
 Keywords:  base_manager   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--
Changes (by Carlton Gibson):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 Grrr... Hi David.

 Can I first say, you pretty much want to forget this bit of the docs
 exists — unless you're super sure what you're doing, and even then, leave
 `_base_manager` well alone. (TBH not sure why it's documented the `_`
 prefix implies private method... — NoteToSelf: should look up why it's
 documented)

 The key point is that the `.filter(question__name__startswith)` bit, as a
 query, will use `Question._default_manager` even though the
 `choice.question` lookup, as a direct access, will use `_base_manager`.

 Have a read of (some of)
 
[https://github.com/django/django/blob/master/django/db/models/fields/related_descriptors.py
 `django/db/models/fields/related_descriptors.py`] to see where
 `_base_manager` is used in this way. (Imagine you have a foreign key to an
 object filtered by `_default_manager` ...)

 I'm not sure this is really addressable. Bar a big warning banner saying
 "Here be dragons" I don't think there's much we can do to clarify this.
 (But concrete suggestions always to be considered...)

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

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[Django] #30222: documentation bug for base managers

2019-02-27 Thread Django 
#30222: documentation bug for base managers
-+--
   Reporter:  David Gudeman  |  Owner:  nobody
   Type:  Bug| Status:  new
  Component:  Documentation  |Version:  2.1
   Severity:  Normal |   Keywords:  base_manager
   Triage Stage:  Unreviewed |  Has patch:  0
Needs documentation:  0  |Needs tests:  0
Patch needs improvement:  0  |  Easy pickings:  0
  UI/UX:  0  |
-+--
 The documentation
 (https://docs.djangoproject.com/en/2.2/topics/db/managers/#base-managers)
 for "Managers->Base managers" seems to contradict itself:

 para 1, line 1: "By default, Django uses an instance of the
 Model._base_manager manager class when accessing related objects"

 para 3, line 1: "Base managers aren’t used when querying on related
 models."

 This is reinforced with an example in para 3, but is then (apparently)
 contradicted again:

 para 4, line 1: "This manager is used to access objects that are related
 to from some other model."

 Furthermore, para 3 give an example of a base model that filters out some
 rows and then in the next section we get a scary-sounding warning not to
 do that or bad things will happen. But the scary warning is odd because it
 seems to be warning me that it will do exactly what I intend it to do. If
 I use the example from para 3, then I *want* it to filter out deleted
 rows. Why is that bad? And especially, why is it bad when para 3 says it
 won't work anyway?

 Finally, para 1 and 2 seem to say that to change Model._base_manager I
 should change Meta.base_manager_name, but doesn't say what the difference
 it makes.

-- 
Ticket URL: 
Django 
The Web framework for perfectionists with deadlines.

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