Rails Controller Variables and Complex Relationships - ruby-on-rails

Question

Let's say we have the following scenario in a Rails application:
Users have many Websites, and Websites have many Simulations (likewise, Websites belong to Users, and Simulations belong to Websites).
Now the problem is, how do I display a list of all of a User's Simulations on the User Show page?
My first gut attempt was to define the following in the Users Controller:
def show
#user = User.find(params[:id])
#websites = #user.websites
#simulations = #user.websites.simulations
end
And then use <%= render #simulations %> in the Users Show Page, but that gives a NoMethodError: undefined methodsimulations' for []:Array` when I visit localhost:3000.
So how can I create a variable in my User Controller that holds all the Simulations that belong to the Websites that belong to a particular User?
Any and all help is greatly appreciated!

Answer 1

class User < ActiveRecord::Base
has_many :websites
has_many :simulations, :through => :websites
end
now you can use #simulations = #user.simulations and get all the user's simulations

Answer 2

In your user model add this method. This will produce 2 queries but still better then joining simulations in ruby code.
def websites_simulations
Simulation.where(website_id: website_ids)
end

Answer 3

Use Erez's answer
You asked for it - I don't know about ruby, but each website in #websites should already contain a field that has a simulation.
This is what you're doing.
1 - You take user, a single object, and get its websites. Cool. User looks something like this (in pseudocode):
Object #user
{
Array[] websites = [(Website)site1, (Website)site2];
}
Alright, that's cool. So user.websites should return an array of websites.
2 - You try to get the simulations from a website. A website probably looks like this:
Object #website
{
Array[] simulations = [(Simulation)sim1, (Simulation)sim2];
}
Hm, why doesn't it work? Well lets break down what you're doing:
#user.websites.simulations
You're taking websites, which is an array, and trying to reference a variable that belongs to a website type and not an array type. #user.websites is an array object that holds websites, not a website itself. What you want is to get #website.simulations, not websites.simulations.
So the first step is getting a website. That's easy - one way would be to try to fetch a website from your website array in the user.
#User.websites[0] <-- may not be syntactically correct; I don't know ruby.
Now if you want to get all of the websites, iterate through them using a loop and push them to a new array. Again in pseudocode:
#all_simulations = new Array();
for(#i=0;#i<count(#user.websites);#i++) //first loop through the websites
{
for(#q=0;#q<count(#user.websites[#i].simulations);#q++) //then loop through the simulations
{
#all_simulations.push(#user.websites[#i].simulations[#q]); //push the simulation into #all_websites
}
}
What we do here is we go into each website in the user.websites array and then grab each simulation from that website and throw that into our #all_simulations variable. If you understand the concept, you should be able to convert this logic into valid ruby.