Disclaimer, I know very little about Rails. I'll try to be succinct. Given the following model relations in Rails:
class ModelA < ActiveRecord::Base
belongs_to :ModelB
...
class ModelB < ActiveRecord::Base
has_many :ModelA
When calling the show action of the ModelA controller the returned JSON should show all ObjectAs that are children of the ObjectB of which the ObjectA in question is a child of.
So if I have an ObjectB that contains ObjectA's of ID 1, 2 and 3 and then access: /modela/1.json
I should see:
{
"modelb": {
"id": "1",
"modela": [insert the ModelA JSON for ID's 1, 2 and 3]
}
}
By default you'll only get the JSON that represents modelb
in your example above. But, you can tell Rails to include the other related objects as well:
def export
@export_data = ModelA.find(params[:id])
respond_to do |format|
format.html
format.json { render :json => @export_data.to_json(:include => :modelb) }
end
end
You can even tell it to exclude certain fields if you don't want to see them in the export:
render :json => @export_data.to_json(:include => { :modelb => { :except => [:created_at, updated_at]}})
Or, include only certain fields:
render :json => @export_data.to_json(:include => { :modelb => { :only => :name }})
And you can nest those as deeply as you need (let's say that ModelB also has_many ModelC):
render :json => @export_data.to_json(:include => { :modelb => { :include => :modelc }})
If you want to include multiple child model associations, you can do the following:
render :json => @export_data.to_json(include: [:modelA, :modelB, :modelN...])
If you want a more flexible approach to rendering json, you can consider using the gem jbuilder: https://github.com/rails/jbuilder
It allows you to render custom attributes, instance variables, associations, reuse json partials in a convenient way.
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