Question

I am developing a Rails web application and am confused about how to utilize the lookup table values in my models. Here is an example model from my app:

table name: donations

id
amount
note
user_id
appeal_id
donation_status_id
donation_type_id
is_anonymous
created_at
updated_at

The fields *donation_status_id* and *donation_type_id* refer to lookup tables. So in my code I have several random places where I make calls like this:

my_donation = Donation.find(params[:id])
if my_donation.donation_status_id == DonationStatus.find_by_name("completed").id
#do something
end

To my inexperienced eyes, a one-off query to the DonationStatus table seems incredibly wasteful here, but I don’t see any other good way to do it. The first idea I thought of was to read all my lookup tables into a hash at application startup and then just query against that when I need to.
But is there a better way to do what I am trying to do? Should I not worry about queries like this?
Thanks!

Answer 1

Since you have two models, you should use ActiveRecord Model Associations when building the models.

class Donation
  has_one :donation_status
end

class DonationStatus
 belongs_to :donation
end

Then when you do

my_donation = Donation.find(params[:id])
if my_donation.donation_status.status_name == 'complete'
  #do something
end

For more information, you may want to read up how rails is doing the model associations http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html Don’t worry about performance, rails has taken care of that for you if you follow how the way it should be done