Michael,
I tried this new model where n3 is your suggestion and n4 is derived from
your suggestion.
db.define_table('mytable',
Field('start_number', 'integer', requires=IS_NOT_EMPTY()),
Field('n1', 'integer', default=request.post_vars.start_number),
Field('n2', 'integer', compute=lambda r: r.start_number),
Field('n3', 'integer', compute=lambda r: r.start_number if not r.n3 else
None),
Field('n4', 'integer', compute=lambda r: r.start_number if r.n4 is None
else r.r4),
)
However, after insert n3 and n4 are both None.
(n1, n2, n3, and n4 are all attempts to meet the same need. I included them
all in one model for comparison.)
Andrew
On Sunday, July 10, 2016 at 8:09:55 PM UTC-6, Michael Beller wrote:
>
> For n2, you could try only updating if n2 was not empty. This is not
> tested but something like ...
>
> Field('n2', 'integer', compute=lambda r: r.start_number if not r.n2 else
> None)
>
>
> On Sunday, July 10, 2016 at 4:38:33 PM UTC-4, ahz...@gmail.com wrote:
>>
>> In my application a user enters a boolean value, and later the user can
>> modify the value*.* I want to save the original value in another field,
>> and the user shouldn't be able to see or alter the original value.
>>
>> Based on the stackoverflow
>> <http://stackoverflow.com/questions/16280220/setting-the-default-of-a-database-field-to-the-value-of-another-field-in-web2py>
>>
>> conversation I tried a simple table with two methods
>> db.define_table('mytable',
>> Field('start_number', 'integer', requires=IS_NOT_EMPTY()),
>> Field('n1', 'integer', default=request.post_vars.start_number),
>> Field('n2', 'integer', compute=lambda r: r.start_number)
>> )
>>
>>
>>
>> Then I used the database administration to insert a value of 5, but *n1 *had
>> a value of zero (instead of 5).
>>
>> While *n2 *started with the value of 5, whenever I modified
>> *start_number*, it also modified *n2*.
>>
>> By the way, I wish I had web2py in 2003 when I started a bigger web
>> application.
>>
>
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