st_*() are db engine functions, you should query the db to get the output
you are looking for. Given that, in your virtual field you should make a
new query, something like that:
Field.Virtual('latitude', lambda row: db(db.location.id == row.location.id).
select(db.location.point.st_x()).first()[db.location.point.st_x()]
Paolo
On Thursday, January 2, 2014 9:59:14 PM UTC+1, Christian Foster Howes wrote:
>
> i bet that by the time your lambda is running the point has been converted
> to a string already. can you see if that is true? i'm not sure how to
> invoke db functions in a lambda of a virtual field. :(
>
> On Wednesday, January 1, 2014 5:50:54 PM UTC-8, User wrote:
>>
>> Suppose I have a table like:
>>
>> db.define_table('location',
>> Field(name, 'string'),
>> Field('point', 'geometry()')
>> )
>>
>> I want to have the latitude and longitude as attributes also (whose value
>> can be derived from the point field). So I try this:
>>
>> db.define_table('location',
>> Field(name, 'string'),
>> Field('point', 'geometry()'),
>> Field.Virtual('latitude', lambda row: row.location.point.st_x()),
>> Field.Virtual('longitude', lambda row: row.location.point.st_y()),
>> )
>>
>> But it doesn't work and fails silently. The model just doesn't have
>> latitude or longitude fields. I also tried with Field.Method but this
>> complains that 'point' is of typer str.
>>
>> I guess the complication is that st_x() translates into a database
>> function. I'm thinking about parsing the point string which is of the form
>> "POINT(x y)" as a workaround but I'd rather use st_x if someone can show me
>> how.
>>
>
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