validation - Validating numeric uniqueness of two attributes in Rails -


i have model track has 2 attributes:

disc represents disc track belongs , number represents numeric order of track on album.

i'd validate uniqueness of track number there can 1 unique track number per disc. instance on disc 1 (or disc 2) there can 1 track track number of 1.

is there pre-existing way in rails' uniqueness validation 1 attribute dependent on another? if not best way write custom validation?

you can try validates_uniqueness_of scope:

validates_uniqueness_of :number, scope: [:disc, album_id]

by way, on database level should validate unique index:

add_index :table_name , [:number, :disc, :album_id], unique: true

or use gem providing composite primary key feature.


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