Optional keys and values
We make a clear distinction between specifying an optional key and an optional value. This gives you a way of being very specific about validation rules. You can define a schema which gives you precise errors when a key is missing or key is present but the value is nil.
This also comes with the benefit of being explicit about the type expectation. In the example below we explicitly state that :age can be omitted or if present it must be an integer and it must be greater than 18.
Optional keys
You can define which keys are optional and define rules for their values:
schema = Dry::Schema.Params do
required(:email).filled(:string)
optional(:age).filled(:integer, gt?: 18)
end
errors = schema.call(email: 'jane@doe.org').errors
puts errors.to_h.inspect
# {}
errors = schema.call(email: 'jane@doe.org', age: 17).errors
puts errors.to_h.inspect
# { :age => ["must be greater than 18"] }
Optional values
When it is allowed for a given value to be nil you can use maybe macro:
schema = Dry::Schema.Params do
required(:email).filled(:string)
optional(:age).maybe(:integer, gt?: 18)
end
errors = schema.call(email: 'jane@doe.org', age: nil).errors
puts errors.to_h.inspect
# {}
errors = schema.call(email: 'jane@doe.org', age: 19).errors
puts errors.to_h.inspect
# {}
errors = schema.call(email: 'jane@doe.org', age: 17).errors
puts errors.to_h.inspect
# { :age => ["must be greater than 18"] }