No need for a loop just do fro the shell:
db(db.persons.new_field==None).update(new_field=0)
Massimo
On Tuesday, 26 July 2016 10:54:19 UTC-5, Ykä Marjanen wrote:
>
> How should I properly initialize old rows after inserting a new field if
> default only updates the new rows? In my case the old rows should also work
> with the new field and value.
>
> Should I do a for loop to manually update all 'old' rows to default value
> after defining the new field?
>
> Ykä
>
> On Tuesday, July 26, 2016 at 5:05:54 PM UTC+3, Niphlod wrote:
>>
>> yep. "default" is something that gets evaluated in python at insert time.
>> Given it takes also a callable, it can't be translated to a proper default
>> constraint on the backend. When you alter the table, you should do so ALSO
>> considering if it's full or empty, and/or that the new column would be
>> meaningful only from a certain "release" onwards.
>>
>> tl;dr: the naming is unfortunate, but "default" doesn't translate to
>> anything in the backend: all the machinery is done on the python layer.
>>
>> On Tuesday, July 26, 2016 at 10:13:19 AM UTC+2, Ykä Marjanen wrote:
>>>
>>> Hi,
>>>
>>> I have been using Web2py for couple years now, but have not been able to
>>> find a decent solution to this issue.
>>>
>>> When creating a new web app I am constantly updating new fields to a
>>> database table after I already have data there. When I add a new field, I
>>> want it to have a default value for it, but for some reason web2py always
>>> has the value at None for the new field even though I have defined it to be
>>> 0.
>>>
>>> For example:
>>>
>>> db.define_table(
>>> 'persons',
>>> Field('old_field','integer',default=0),
>>> Field('new_field','integer',default=0)
>>> )
>>>
>>> The new_field is now updated to the table correctly, but instead of 0 it
>>> is None for the old records.
>>>
>>> This is annoying as I am assuming old tables to have the new_field also
>>> set as 0 and now I must write code to assume None and change it manually to
>>> 0.
>>>
>>> Am I missing something?
>>>
>>> Ykä
>>>
>>>
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