Question

Pretty basic Rails question I assume but I can’t figure out the simplicity of Rails.

My simple goal is to have a user submit a form indicating the amount of a donation, and have that donation linked to the user. I’m having trouble with the create action in the donations_controller.rb

I have a User.rb model and a Donation.rb model. The User.rb has_one :donation and Donation.rb belongs_to :user. I am also using Devise so I have the current_user method.

My donation table looks like this

class CreateDonations < ActiveRecord::Migration
  def change
    create_table :donations do |t|
      t.integer :amount
      t.integer :user_id

      t.timestamps
    end
    add_index :donations, [:user_id, :created_at]
  end
end

The _form.html.erb for the donations_controller.rb looks like this

<%= form_for @donation do |f| %>

  <div class="field">
    <%= f.number_field :amount %>
  </div>
  <div class="actions">
    <%= f.submit "Submit" %>
  </div>
<% end %>

The create action in donations_controller.rb looks like this

def create
    @donation  = current_user.donation.build(params[:donation])
    if @donation.save
      flash[:success] = "Donation"
      redirect_to root_path
    else
      render 'home/index'
    end
  end

I’m getting this error message when I submit the form.

NoMethodError in DonationsController#create

undefined method `build' for nil:NilClass

Answer 1

The method for building the has_one association is current_user.build_donation(params[:donation])