[Django] #29306: [bugs for all version]Template variable-lookups system evaluate callables before completed the evaluation
Django
before completed the evaluation
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Reporter: Luoxzhg | Owner: nobody
Type: Bug | Status: new
Component: Template system | Version: master
Severity: Normal | Keywords: template
Triage Stage: Unreviewed | Has patch: 1
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 1
UI/UX: 0 |
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{{{
class A:
class B:
attr="Hello"
from django.template import Template, Context
t = Template(" {{ A.B.attr }}")
output=t.render(Context({"A": A}))
}}}
the output should be "Hello", but it is string_if_invalid, i.e., empty
string "" .
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Ticket URL: <https://code.djangoproject.com/ticket/29306>
Django <https://code.djangoproject.com/>
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Django
attribute
---------------------------------+--------------------------------------
Reporter: Luoxzhg | Owner: nobody
Type: Bug | Status: new
Component: Template system | Version: master
Keywords: template | Triage Stage: Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
Description changed by Luoxzhg:
Old description:
> {{{
> class A:
> class B:
> attr="Hello"
>
> from django.template import Template, Context
> t = Template(" {{ A.B.attr }}")
> output=t.render(Context({"A": A}))
> }}}
>
> the output should be "Hello", but it is string_if_invalid, i.e., empty
> string "" .
New description:
{{{
class A:
def __init__(self, value):
pass
attr="Hello"
from django.template import Template, Context
t = Template(" {{ A.attr }}")
output=t.render(Context({"A": A}))
}}}
the output should be "Hello", but it is string_if_invalid, i.e., empty
string "" .
--
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Ticket URL: <https://code.djangoproject.com/ticket/29306#comment:1>
Django
attribute
---------------------------------+--------------------------------------
Type: Bug | Status: assigned
Component: Template system | Version: master
Keywords: template | Triage Stage: Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
Changes (by Luoxzhg):
* status: new => assigned
* owner: nobody => Luoxzhg
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Ticket URL: <https://code.djangoproject.com/ticket/29306#comment:2>
Django
---------------------------------+------------------------------------
Reporter: Luoxzhg | Owner: Luoxzhg
Type: Bug | Status: assigned
Keywords: template | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
---------------------------------+------------------------------------
Changes (by Tim Graham):
* stage: Unreviewed => Accepted
* easy: 1 => 0
Comment:
[https://github.com/django/django/pull/9864 PR]
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Ticket URL: <https://code.djangoproject.com/ticket/29306#comment:3>
Django
---------------------------------+------------------------------------
Reporter: Luoxzhg | Owner: Luoxzhg
Type: Bug | Status: assigned
Keywords: template | Triage Stage: Accepted
Needs tests: 0 | Patch needs improvement: 0
---------------------------------+------------------------------------
Comment (by Tim Graham):
I understand the desire for the behavior change, however, the change could
be backwards incompatible. Consider this case which will pass before the
change but fail afterward:
{{{
@setup({'t': '{{ A.attr }}'})
def test_class_attribute(self):
"""Accessing an attribute of an instantiated class."""
class A:
def __init__(self):
self.attr = 'Hello'
self.assertEqual(self.engine.render_to_string('t', {'A': A}), 'Hello')
}}}
Is there any documentation to suggest
[https://docs.djangoproject.com/en/dev/ref/templates/language/#variables
the current behavior] is incorrect?
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Ticket URL: <https://code.djangoproject.com/ticket/29306#comment:4>
Django
Reporter: Luoxzhg | Owner: Luoxzhg
Type: Bug | Status: closed
Component: Template system | Version: master
Keywords: template | Triage Stage: Accepted
Needs tests: 0 | Patch needs improvement: 0
---------------------------------+-------------------------------------
Changes (by Carlton Gibson):
* status: assigned => closed
* resolution: => duplicate
Comment:
I think this is expected behaviour, that has a workaround.
#15791 added a check for a `do_not_call_in_templates` attribute on a
callable.
Setting this to `True` in the example test case allows it to pass.
This is documented in the
[https://docs.djangoproject.com/en/2.0/ref/templates/api/#variables-and-
lookups Variables and lookups] section of the Template API docs.
Closing as a duplicate of #15791
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Ticket URL: <https://code.djangoproject.com/ticket/29306#comment:5>