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How to add records to has_many :through association

Wes asked in Rails

I have three models called Site, Model and ModelSite as shown below. If i create a new model_site i can choose a site and model to save which works good but what i need help in is how can i choose a site or model if I'm creating a new site or model? I'm showing an example on how i create a new site which has a .association :sites input. I can pick the sites but it does not get saved.

class Site < ActiveRecord::Base
  has_many :model_sites, inverse_of: :site, dependent: :destroy
  has_many :models, through: :model_sites

class ModelSite < ActiveRecord::Base
 belongs_to :model
 belongs_to :site
 validates_presence_of :model, :site

class Model < ActiveRecord::Base
 has_many :model_sites, inverse_of: :model, dependent: :destroy
 has_many :sites, through: :model_sites

New site

<%= simple_form_for [:admin, @model] do |f| %>
 <%= f.input :name %>
 <%= f.association :sites, as: :check_boxes %>
<% end %>

Something like this may work?

<%= f.label :name %>
<%= f.collection_check_boxes(:site_ids, Sites.all, :id, :name) %>

Plus another way on Stack Overflow:


I did try that and it still does not save. I'm assigning the site_id and model_id which has to be saved by creating a new ModelSite. I need to find a way to save those id's when creating a new site or model.


Hey Wesley,

So you said that this is a form for a new Site? A site has_many models, not many sites. Should your form be for association :sites instead?


+1 on what Chris said. Also, it should not cause any conflicts but out of curiosity why did you choose Model as a Model name? Not criticism, just curious.


I do have it as that Chris but i guess i actually cant save it through a model or site i have to create it through the model_site Model.

I could have called my Model girl instead of model to not confuse anything but having the word Model just sounded better to me.

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