Rails 3 Nested Resource Variables

Question

I have a few questions relating to a Transaction object that I'm creating.

Transaction belongs_to Loan and Loan has_many Transactions.

Therefore, I setup a nested route:

resources :loans do
  resources :transactions
end

My question is: How do I pass the loan value into the Transaction's 'loan_id' field? Is this best done in the controller or as a hidden_field in the form? Does the nested route create an easy way to grab this variable?

I assumed this would be done automatically, but the field is empty when I saved it as-is.

Any help would be greatly appreciated!

Andrei S · Accepted Answer · 2011-05-18 20:43:33Z

2

if you call a specific transaction, the route for a new transaction will be

loans/:loan_id/transactions/new

you could use model association like this: in your create action:

@transaction = Loan.find(params[:loan_id]).transactions.build

that way your new @transaction will be already populated with the loan_id

answered May 18, 2011 at 20:43

Andrei S

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7 Comments

Justin Over a year ago

I just tried this and I got the following message: Couldn't find Loan without an ID. Do you why the :loan_id isn't being recognized?

Andrei S Over a year ago

make sure you have a loan in the database with the :loan_id you're trying to call. calling find on Loan will raise an exception if the loan with the id = loan_id does not exist - that should only happen if you type the url manually

Justin Over a year ago

The Loan exists and I'm linking to it with <%= link_to 'Lend Now', new_loan_transaction_path(@loan), :class => 'lend_button' %> Is that correct? It's still throwing the error for some reason. Thanks for the added help!

Andrei S Over a year ago

the link is correct (the action new, for a transaction in @loan). when is the error thrown? in the new or create action? what prints if you puts params[:loan_id]? is it the id of the called loan?

Justin Over a year ago

The error is thrown right after submitting the new Transaction form and it's titled ActiveRecord::RecordNotFound in TransactionsController#create. So, it's in the create method. There appears to be nothing in the params[:loan_id]. For some reason, I don't think the two are connecting. Is there something I need to add beyond what I have above to the routes perhaps? Thanks again, I really appreciate the help!

|

Chadwick · Accepted Answer · 2011-10-20 14:29:54Z

0

Consider adding a before_filter to your controller and having it call a private method to grab the :id across all actions. Place this at the top of your transactions controller:

before_filter :load_loan

And then after all the actions, add:

private
def load_loan
  @loan.find(params[:loan_id])
end

Use it like this in your new action:

@transaction = @loan.transactions.build

edited Oct 20, 2011 at 14:29

Chadwick

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answered Oct 20, 2011 at 11:22

Paul Simpson

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