Creating nested/reusable validators in Ruby with dry-validation - ruby

Question

Let's say I want to set up a validation contract for addresses, but then I also want to set up a validator for users, and for coffee shops; both of which include an address, is it possible to re-use the AddressContract in UserContract and CoffeeShopContract?
For example, the data I want to validate might look like:
# Address
{
"first_line": "100 Main street",
"zipcode": "12345",
}
# User
{
"first_name": "Joe",
"last_name": "Bloggs",
"address:" {
"first_line": "123 Boulevard",
"zipcode": "12346",
}
}
# Coffee Shop
{
"shop": "Central Perk",
"floor_space": "2000sqm",
"address:" {
"first_line": "126 Boulevard",
"zipcode": "12347",
}
}

Answer 1

Yes you can reuse schemas (See: Reusing Schemas)
It would look something like this:
require 'dry/validation'
class AddressContract < Dry::Validation::Contract
params do
required(:first_line).value(:string)
required(:zipcode).value(:string)
end
end
class UserContract < Dry::Validation::Contract
params do
required(:first_name).value(:string)
required(:last_name).value(:string)
required(:address).schema(AddressContract.schema)
end
end
a = {first_line: '123 Street Rd'}
u = {first_name: 'engineers', last_name: 'mnky', address: a }
AddressContract.new.(a)
#=> #<Dry::Validation::Result{:first_line=>"123 Street Rd"} errors={:zipcode=>["is missing"]}>
UserContract.new.(u)
#=> #<Dry::Validation::Result{:first_name=>"engineers", :last_name=>"mnky", :address=>{:first_line=>"123 Street Rd"}} errors={:address=>{:zipcode=>["is missing"]}}>
Alternatively you can create schema mixins as well e.g.
AddressSchema = Dry::Schema.Params do
required(:first_line).value(:string)
required(:zipcode).value(:string)
end
class AddressContract < Dry::Validation::Contract
params(AddressSchema)
end
class UserContract < Dry::Validation::Contract
params do
required(:first_name).value(:string)
required(:last_name).value(:string)
required(:address).schema(AddressSchema)
end
end