[Django] #23114: Template Variables Docs Incorrect/Unclear
Django
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Reporter: tom.dalton@… | Owner: nobody
Type: Bug | Status: new
Component: Documentation | Version: 1.6
Severity: Normal | Keywords: template
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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On this section
https://docs.djangoproject.com/en/1.6/topics/templates/#variables
In the "Behind the Scenes" section, it gives the order that Django tries
to resolve a variable like "X.Y".
The 4 things that it tries are accurate, but the way/order they're done
doesn't appear to be correct.
Ref the code that does this:
https://github.com/django/django/blob/master/django/template/base.py#L756
What actually (seems to) happen is:
* Try dictionary lookup to get "thing"
* If not found "thing", try attribute lookup to get "thing"
* If not found "thing", try list-index lookup to get "thing"
* If not found "thing", then fail
* If "thing" is callable, then "thing" = "thing()"
* Return "thing"
Applies in version 1.6 and onwards, probably applicable to older doc
versions too.
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Ticket URL: <https://code.djangoproject.com/ticket/23114>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
Django
Reporter: tom.dalton@… | Owner: nobody
Type: Bug | Status: new
Component: Documentation | Version: 1.6
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Changes (by bmispelon):
* needs_better_patch: => 0
* stage: Unreviewed => Accepted
* easy: 0 => 1
* needs_tests: => 0
* needs_docs: => 0
Comment:
Hi,
It seems this list has remained largely unchanged since its initial
introduction (096ad32c845f850278b942d087e607dc4311b5f9).
I don't see a reason to distinguish argument lookups and method calls. I
think we could simply merge the two items into one: "Attribute/method
lookup".
THanks
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:1>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: assigned
Component: Documentation | Version: 1.6
Severity: Normal | Resolution:
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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* owner: nobody => gmunumel
* status: new => assigned
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:2>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: assigned
Severity: Normal | Resolution:
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by anonymous):
Even that's not quite accurate, since it tries the initial lookup (dict
then attribute then list index). Once it's got that value, it then calls
it if possible.
So maybe the docs should say something like:
Value lookup is done in the following order:
* dict-key
* attribute
* list-index
If the value is callable, it is called, and the value becomes the result
of that call.
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:3>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: assigned
Severity: Normal | Resolution:
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by tom.dalton@…):
So I guess I'm saying there are 2 issues:
1. The Attribute lookup vs Method call thing.
2. It's not stated that other values (e.g. if dictionary or list lookup
worked) are actually called. The docs imply only methods are called.
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:4>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: assigned
Severity: Normal | Resolution:
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by bmispelon):
Yes, good point.
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:5>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: assigned
Severity: Normal | Resolution:
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by gmunumel):
Here is the pull request [https://github.com/django/django/pull/2994].
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:6>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: assigned
Severity: Normal | Resolution:
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by anonymous):
Thanks for that. I added a comment to the pull request with a patch for a
slightly more comprehensive rework to include the stuff talked about
enough. I don't think that just combining attribute/method lookup is
enough to clarify what Django actually does behind the scenes.
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:7>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Component: Documentation | Version: 1.6
Severity: Normal | Resolution: fixed
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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* status: assigned => closed
* resolution: => fixed
Comment:
In [changeset:"62c74abbb06a081708c2cb5cc459f39beb26acaa"]:
{{{
#!CommitTicketReference repository=""
revision="62c74abbb06a081708c2cb5cc459f39beb26acaa"
Fixed #23114 -- Clarified documentation of template lookups.
Thanks to gmunumel and Tom Dalton for their help on the patch.
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:8>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: closed
Severity: Normal | Resolution: fixed
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by Baptiste Mispelon <bmispelon@…>):
In [changeset:"13d44f54a265e9fc6185e1d5518da8ad568fbaad"]:
{{{
#!CommitTicketReference repository=""
revision="13d44f54a265e9fc6185e1d5518da8ad568fbaad"
[1.7.x] Fixed #23114 -- Clarified documentation of template lookups.
Thanks to gmunumel and Tom Dalton for their help on the patch.
Backport of 62c74abbb06a081708c2cb5cc459f39beb26acaa from master.
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:9>
Django
Reporter: tom.dalton@… | Owner: gmunumel
Type: Bug | Status: closed
Severity: Normal | Resolution: fixed
Keywords: template | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Comment (by anonymous):
Thanks for the speedy resolution!
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Ticket URL: <https://code.djangoproject.com/ticket/23114#comment:10>