Rails - Feb 2008 - Foreign keys not displayed for user input in create function

Newbie to Ruby - would appreciate it enormously if somebody could help
me with this.

In my create function, for a specific table, my foreign keys in that
table are not visible for selection. However, at the time of writing
to the database, they take one or the other values on these foreing
keys. I carried out the validates_presence_of on these foreign keys
and that started generating errors but it still did not show the
foreign keys.

Example

Exam                 |---------<           
Exam_Subjects
>--------|        Subjects
Exam_id                                     Exam_id  (foreign-
key)                      Subject_id
Exam_Name                               Subject_id (foreign-
key)                     Subject_Name
                                                  Percent_of_questions
 
Difficulty_level_of_subjects

After generating the scaffolding, when I go to exam_subject/create
screen, it only displays text-boxes to input Percent_of_questions and
Difficulty_level_of_subjects. Its doesnt show Subject_id or Exam_id
for input and takes default values to fill it.

What I need is drop downs for Exam_Name and Subject_Name.

I tried using the validates_presence_of Exam_id which actually
resulted in generating an error but still no way of beinbg able to
show the name fields for input.

I was going to write a code but think there must be some ruby method I
can use to show all foreign keys for input? Is there one? Am I missing
something?

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Hi Sky,

You need to add something like this to your form assuming you are
using form_for:-

<%= f.select(''exam_id'', @exams.collect {|exam| [exam.name,
exam.id ]})
%>

You''ll initialise exams instance variable in your controller (@exams
Exam.find(:all)). You need to do something similar for the the Subject
drop down. I hope that answers your question?

Jabbslad

On Feb 28, 9:54 am, Skywalker
<vikram.b...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Newbie to Ruby - would appreciate it enormously if somebody could help
> me with this.
>
> In my create function, for a specific table, my foreign keys in that
> table are not visible for selection. However, at the time of writing
> to the database, they take one or the other values on these foreing
> keys. I carried out the validates_presence_of on these foreign keys
> and that started generating errors but it still did not show the
> foreign keys.
>
> Example
>
> Exam                 |---------<            Exam_Subjects>--------|  
Subjects
>
> Exam_id                                     Exam_id  (foreign-
> key)                      Subject_id
> Exam_Name                               Subject_id (foreign-
> key)                     Subject_Name
>                                                   Percent_of_questions
>
> Difficulty_level_of_subjects
>
> After generating the scaffolding, when I go to exam_subject/create
> screen, it only displays text-boxes to input Percent_of_questions and
> Difficulty_level_of_subjects. Its doesnt show Subject_id or Exam_id
> for input and takes default values to fill it.
>
> What I need is drop downs for Exam_Name and Subject_Name.
>
> I tried using the validates_presence_of Exam_id which actually
> resulted in generating an error but still no way of beinbg able to
> show the name fields for input.
>
> I was going to write a code but think there must be some ruby method I
> can use to show all foreign keys for input? Is there one? Am I missing
> something?
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