#27081: DateField with current date intitialisation pypy migration issue
-------------------------------+--------------------------------------
     Reporter:  Kurdakov       |                    Owner:  nobody
         Type:  Uncategorized  |                   Status:  new
    Component:  Uncategorized  |                  Version:  1.9
     Severity:  Normal         |               Resolution:
     Keywords:                 |             Triage Stage:  Unreviewed
    Has patch:  0              |      Needs documentation:  0
  Needs tests:  0              |  Patch needs improvement:  0
Easy pickings:  0              |                    UI/UX:  0
-------------------------------+--------------------------------------
Changes (by Kurdakov):

 * needs_better_patch:   => 0
 * needs_tests:   => 0
 * needs_docs:   => 0


Old description:

> if model contains DateField and it is initialized with current date
>
> example:
>
> from datetime import date
>
> class TestClass(models.Model):
>
>     start_date = models.DateField(
>         verbose_name=u'start date',
>         default=date.today,
>         )
>
> pypy migrations will fail
>
> django/db/migrations/writer.py", line 540, in serialize
>     "topics/migrations/#migration-serializing" % (value,
> get_docs_version())
> ValueError: Cannot serialize: <bound method type.today of <class
> 'datetime.date'>>
>
> reason:
> code for serialising methods in Django checks
> `if isinstance(value, (types.FunctionType, types.BuiltinFunctionType))`
> which succeeds on cpython because datetime.date.today is a
> BuiltinFunctionType, wheras it's a types.MethodType on pypy and this
> check is missing in django
> ( link
> https://github.com/django/django/blob/3b383085fb89a48e756383e7cd5d3bd867353ba1/django/db/migrations/serializer.py#L379
> )
>
> a solution for client code is to declare local function
>
> def today():
>     return date.today()
>
> but would be better to add types.MethodType check for pypy compatibility
> class TestClass(models.Model):
>
>     start_date = models.DateField(
>         verbose_name=u'start date',
>         default=today,
>         )

New description:

 if model contains DateField and it is initialized with current date

 example:

 from datetime import date
 {{{
 #!python
 class TestClass(models.Model):

     start_date = models.DateField(
         verbose_name=u'start date',
         default=date.today,
         )
 }}}
 pypy migrations will fail

 django/db/migrations/writer.py", line 540, in serialize
 "topics/migrations/#migration-serializing" % (value, get_docs_version())
 ValueError: Cannot serialize: <bound method type.today of <class
 'datetime.date'>>

 reason:
 code for serialising methods in Django checks
 `if isinstance(value, (types.FunctionType, types.BuiltinFunctionType))`
 which succeeds on cpython because datetime.date.today is a
 BuiltinFunctionType, wheras it's a types.MethodType on pypy and this check
 is missing in django
 ( link
 
https://github.com/django/django/blob/3b383085fb89a48e756383e7cd5d3bd867353ba1/django/db/migrations/serializer.py#L379
 )

 a solution for client code is to declare local function
 {{{
 #!python

 def today():
     return date.today()


 class TestClass(models.Model):

     start_date = models.DateField(
         verbose_name=u'start date',
         default=today,
         )
 }}}

 but would be better to add types.MethodType check for pypy compatibility

--

--
Ticket URL: <https://code.djangoproject.com/ticket/27081#comment:1>
Django <https://code.djangoproject.com/>
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