Ruby on Rails

On 1 July 2015 at 17:16, John Lahr <johnelahr@gmail.com> wrote:
> Colin
>
> Thanks for your answer. The student/class thing was just an example - the
> actual stuff I'd be building has nothing to do with students and classes it
> was just the easiest thing that came to me.
>
> You can do a validation on a total number of related records? I did not
> know that.

You can write a custom validation to do anything you like. The world
is your mollusc.

Colin

>
> On Wed, Jul 1, 2015 at 8:59 AM, Colin Law <clanlaw@gmail.com> wrote:
>>
>> On 1 July 2015 at 16:51, John Lahr <johnelahr@gmail.com> wrote:
>> > Can you limit the number of related records a given parent record has?
>> >
>> > Example. Class/Student relatoinship. A Class has_many students but I
>> > want
>> > to limit the size of a class to a max 30 (of course minimum or exact
>> > numbers
>> > would hopefully work the same way?)
>>
>> There may be a better way but I would just use a validation that
>> prevents further students being added to the class when the limit is
>> released.
>>
>> By the way, can a student be in more than one class? If so then you
>> need has and belongs to many or (which I prefer) has many through.
>>
>> Colin
>>
>> >
>> >
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