José Mota — The blog

Rails 3 has_many :through checkboxes

05 November 2010

  • development

On Twitter I wrote:

Rails does it for you, just add sheet_ids[] to the form with the checkboxes and it's done! will blog.

Being a music teacher, my fiance needed to keep record of tests her students perform. Also, each test has several sheets that need mentoring and monitorization through several parameters. I decided to help and reentered the Rails world, and since I have found no answer on this topic, I decided to write it myself.

This situation is a perfect model for using the so well known HABTM checkboxes.

A closer look at the problem


A pretty basic setup. The venues (the students' tests) include several sheets for them to study and for the teacher to evaluate, through exhibitions that have several criteria.


I simplified the form just so you see what's at stake. The same principle of the HABTM checkboxes applies to a hasmany :through association. Instead of new entries in a venuessheets table, new Exhibitions are created with the respective foreign ids in them.

The controller needs no mention because it stays the same. It just saves / updates the model. This is why I love Rails: the hard work is done: you just need to focus on what matters.

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