Add validator if another field has a specific value

[Daniel Crisan]

Hello,

I have a form with 2 inputs (textboxes, checkboxes, doesn't matter) and I need to add a validator for another field only if one of the inputs is equal to some value.

Is this possible?

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[Matteo Landi]

On Wed, Jun 5, 2013 at 6:02 PM, Daniel Crisan <crisan...@gmail.com> wrote:
> Hello,
>
> I have a form with 2 inputs (textboxes, checkboxes, doesn't matter) and I
> need to add a validator for another field only if one of the inputs is equal
> to some value.
>
> Is this possible?

Sure, by using a general form validator. Have a look at the following snippet:

signup = form.Form(
form.Textbox('username'),
form.Password('password'),
form.Password('password_again'),
validators = [form.Validator("Passwords didn't match.", lambda i:
i.password == i.password_again)]
)

As you can see, when you create a form you can pass an additional list
of which that can work on the form as whole (i.e. access all the
registered fields); there shouldn't be too hard to adapt the previous
example to your specific use case.

Please, get back to us if you need further help.


Cheers,

Matteo

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[Daniel Crisan]

Yes, you are right but that is the case when you can compare the value from one field with the one from another field. It's a bit complicated. There are more than 2 fields and different cases like:

 if field_1 == '"some value"'

       if field_2 == "some value"

              field_3 must be ....

       if field_2 == "other value"

              field_3 must be.....

Anyway, solved the issue (don't have the code here but as I recall it it goes something like):

args = ()

args = args + (form inputs.....,)

class page():

     def __init__(self): - will define validators and the form as class variables

         self.v=[] - this will hold the validators

         self.myform =form.Form(validators=self.v, *args)

     def GET()

          define the classic GET here

     def POST():

          pdata = web.input(checkboxes_array_with_same_name=[])

          if not self.myform.validates(pdata):

               return render.page(self.myform)

          else:

               if pdata.some_input == do all the checks here

                        if pdata.some_other_input - do some other checks and if necessary make another if

                              self.v.append(form.Validator("error message", False)

                              self.myform = form.Form(validators=self.v, *args)

                              return render.page(self.myform)

               elif .....add additional restrictions based on any post data received 

               else:

                      code for form valid

I don't see anything wrong with this approach, it loops the same page until the form data is valid. Do you see something wrong?

[Matteo Landi]

On Thu, Jun 6, 2013 at 12:49 PM, Daniel Crisan <crisan...@gmail.com> wrote:
> Yes, you are right but that is the case when you can compare the value from
> one field with the one from another field. It's a bit complicated. There are
> more than 2 fields and different cases like:
> if field_1 == '"some value"'
> if field_2 == "some value"
> field_3 must be ....
> if field_2 == "other value"
> field_3 must be.....

I don't see why you shouldn't be able to implement this using a form validator.

There is nothing wrong with that besides a less maintainable
controller; compare the snippet above with one missing the the else
branch (all the validation logic has been segregated into the form
validator): you will agree with me that the resulting controller
would be easier to read and maintain.


Cheers,

Matteo