Creating a many to many relationship in rails 4 -


how can create relationship table in migration class both references used in unique index?

class creatediagnostichypotheses < activerecord::migration   def change     create_table :diagnostic_hypotheses, :id => false |t|       t.references :accident_indication, index: true       t.references :forms, index: true        t.timestamps null: false     end      add_foreign_key :diagnostic_hypotheses, :accident_indications     add_foreign_key :diagnostic_hypotheses, :forms, column: :diagnostic_hypothesis_id   end end

when run rake db:migrate tries create separate indexes. how can create 1 unique index both :accident_indication , :forms references?

you can create unique composite index:

class creatediagnostichypotheses < activerecord::migration   def change     create_table :diagnostic_hypotheses, :id => false |t|       t.references :accident_indication       t.references :forms        t.timestamps null: false     end      add_index :diagnostic_hypotheses, [:accident_indication_id, :forms_id], :unique => true      add_foreign_key :diagnostic_hypotheses, :accident_indications     add_foreign_key :diagnostic_hypotheses, :forms, column: :diagnostic_hypothesis_id   end end

i didn't try myself, however, think you've got idea.


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