Question

Table: Raw_Data
Fields: id
name

Table: Actual_Data
Fields: id
raw_data_id
name

A use can either add data manually to Actual_Data (in which case it’s raw_data_id is NULL) or they can select a Raw_Data to insert into Actual_Data (in which case it’s raw_data_id is set).

Is the following relationships correct in this case?

For Raw_Data:
-none-

For Actual_Data:
has_one :raw_data

Answer 1

You are right the relationship should be the same as you said,

class ActualDate < ActiveRecord::Base
  has_one :raw_data
end

class RawData < ActiveRecord::Base
  belong_to :actual_data
end

As per the rails convention, the foreign key should belongs to the table which has belongs_to association, so here actual_data_id should be in raw_datas table.

Edit:
We don’t need raw_data_id in actual_datas table.