Re: [Rails] Limiting the number of related records (has_many, but max number?)

Ruby on Rails Wednesday, July 1, 2015

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.

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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Posted by Ruby on Rails at 9:16 AM

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