belongs_to :model validation with mandatory foreign keys and foreign key at DB layer

rubyonrails-talk
1

Hi Folks,

First Question

I want to learn that there is a native way make building normal and mandatory belongs_to associations. Let give a simple example, I have two models, first one is Tenant, second is User. User belongs to Tenant which mean there is a User.tenant_id. I can create, save or update User Model without User.tenant_id . I named this is normal belongs_to . What i want is User model can’t update or save if tenant_id = nil.

What is the best solution for this problem.

My schema is https://github.com/kebab-project/server-ror/blob/master/db/schema.rb

My models are https://github.com/kebab-project/server-ror/tree/master/app/models

My migrations are https://github.com/kebab-project/server-ror/tree/master/db/migrate

Note : User Model extends from TenantScope model!

Second Question

I see that rails doesn’t add foreign key at DB layer. There are several gems for this issue. But i can’t understand why we don’t add foreign key. Why this is a good idea? Is it over performance or portability?

Best Regards.

2

Use a validation in the User model. See the Rails Guide on Active Record Validations and Callbacks.

Colin

3

Hi Folks,

*First Question*

I want to learn that there is a native way make building normal and mandatory belongs_to associations. Let give a simple example, I have two models, first one is Tenant, second is User. User belongs to Tenant which mean there is a User.tenant_id. I can create, save or update User Model without User.tenant_id . I named this is normal belongs_to . What i want is User model can't update or save if tenant_id = nil.

When you add the column, make it a not null column.

* I see that rails doesn't add foreign key at DB layer. There are several gems for this issue. But i can't understand why we don't add foreign key. Why this is a good idea? Is it over performance or portability?

There is a school of thought that says that the database shouldn't have any application/business logic. Personally I always use foreign keys, unique indexes etc - only the database itself can give me a cast iron guarantee for those things - rails validations are subject to race conditions in some cases (and of course don't help you if you ever manipulate data outside of rails)

Fred