Aha, thanks for both the great answers. I had a slight idea as to what each were, but I had never seen those variations of the syntax. Thanks again.
On Aug 1, 11:14 am, Yarko Tymciurak <[email protected]> wrote: > On Sat, Aug 1, 2009 at 5:00 AM, Fran <[email protected]> wrote: > > > On Aug 1, 3:32 am, Alastair Medford <[email protected]> wrote: > > > > db.student.student_id.requires=IS_NOT_IN_DB(db,'student.student_id') > > > > db.tasks.student.requires=IS_IN_DB(db,'student.id','%(student_id)s') > > > > db.tasks.student.represent=lambda id: db.student[id].student_id > > > This seems to accomplish what I was trying to do, thanks. However, I'm > > > in the dark as to what some of the syntax is. In the second line, I > > > know that the third argument has something to do with how the drop > > > down box chooses it's contents, but I do not understand the syntax of > > > '%(student_id)s'. Also, in the 3rd line I do not know what "lambda id: > > > " is doing. If this is standard python fare, then I apologise as I'm > > > still learning python and all it's syntax tricks. Thanks again. > > > These are both std Python. > > > '%(student_id)s' => replace '' with the value of student_id > > you can google "python string substitution - it is based on the C > language's printf % codes, > so where in a C string you would have: > > printf(" this is my name: %s %s\n", first_name, last_name) > > where %s is a string, replaced by the first argument (in this case a > variable called 'name') > > Python string substitution, there are a few ways to accomplish something > similar: > > "this is my name: %s %s" % first_name, last_name > > will replace the %s with the contents of name; if you have a form email. > for example, you would could have a preformatted template, and load it with > different variables at each use. > > If you wanted to load a template with the same variables each time (and let > the variable contents change), then you could equivalently write this as: > > "this is my name: %(first_name)s %(last_name)s" > > lambda functions allow you to use a little program to fill in the > > > value > > so lambda id: db.student[id].student_id > > says 'use the value of this cell within the formula db.student > > [value].student_id' > >http://diveintopython.org/power_of_introspection/lambda_functions.html > > That is a good link - think of lambda functions as anaonymous, or inline > functions (functions without a name) > > > > > F --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
