The graphql-ruby gem has a built-in blank validator:
class Mutations::UserUpdate < Mutations::BaseMutation
null true
argument :user_id,
String,
"Identifier of user",
required: true,
validates: {allow_blank: false}
field :user_id, String, null: false
def resolve(user_id:)
{user_id:}
end
end
So now a mutation with a user_id of " " will cause the graphql response to have an error:
mutation UserUpdate($userId: String!) {
userUpdate(userId: $userId) {
userId
}
}