Model Structure in Rails

Question

I'm relatively new to Rails and I'm trying to figure out the ideal model structure for my application, which is a simple reminder service for home maintenance. The central model in the app is a Home.

Each home has many Appliance in it (i.e. a dishwasher, laundry, water heater etc).

Each Appliance has a set of reminders associated with it (i.e. if you have a water heater, you have to do XYZ every 3 months, and ABC every 6 months).

On a regular basis (monthly/weekly), there is a mailer sent to the homeowner with a list of all the reminders.

I'm trying to figure out the best model structure for this.

Right now, these are the models I have but I don't know if this is overkill or not?

Home (Address, Postal Code, etc)
Appliance (Name, Manufacturer)
Reminder (Appliance_ID, Reminder, Frequency)
HomeAppliance (Home_ID, Appliance_ID)
HomeReminders (Home_ID, Reminder_ID)

The Associations:

Home has_many HomeAppliances
Appliance has_many Reminders
Home has_many HomeReminders

Any help is appreciated.

David Underwood · Accepted Answer · 2012-04-28 16:37:47Z

1

I'd go for something a little less complex. You need three models:

class Home < ActiveRecord::Base
  has_many :appliances
  has_many :reminders, :through => :appliances
end

class Appliance < ActiveRecord::Base
  belongs_to :home
  has_many :reminders
end

class Reminder < ActiveRecord::Base
  belongs_to :appliance
end

Notice that we're using the has_many :through relation to allow us to call home.reminders directly.

See the Document example here for more info on has_many :through: http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association

In your original example you seem to want to store various pre-defined appliances in the db for reference. I'd do it differently. Have a config file with the various makes and models that you can use to populate dropdowns on the form users use when setting up their appliance details. Then you can skip the extra models and simplify things as described above.

edited Apr 28, 2012 at 16:37

answered Apr 28, 2012 at 16:02

David Underwood

4,9761 gold badge21 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

tarunsachdeva Over a year ago

Thanks, this is what I initially thought, but wouldn't this result in so much repeated information in the DB? For example, if a Home has multiple Appliances, the Appliance table will have multiple rows for each Home, with each row containing detailed information about the Appliance. ALso, if an Appliance has_many Reminders, the reminder info for each appliance will be repeated in every row the Reminder table. Each reminder can contain a paragraph of information. I was thinking of modelling this similar to how "Relationships" are modelled between users. Thoughts?

tarunsachdeva Over a year ago

This is why I had created a models akin to "Relationships" for the home (HomeAppliance and HomeReminder).

David Underwood Over a year ago

If you're worried about running out of space due to duplications then yes, adding the lookup table for the home -> appliance mapping is a good idea. I'd still use the has_many :through relation to avoid having a relation lookup table assuming that all it's doing is mapping appliances to reminders.

Collectives™ on Stack Overflow

Model Structure in Rails

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related