Requiring one of 2 Arguments to be required

[RobsonKing]

I have a field that I want to filter in one of two ways.

    field :car, Types::CarType, null: false do
      argument :id, ID, required: true
      argument :external_id, ID, required: false
    end

Is there anyway to indicate that one of the two values must be required, but not both?

I tried overriding GraphQL::Schema::Argument, but it doesn't seem like 'context' is available where 'required' is used.

[jturkel]

This sounds like a good use case input unions in GraphQL to support schema level enforcement of this contract. See graphql/graphql-spec#395 for more on that.

In the meantime the best you can do is a runtime validation check:

field :car, Types::CarType, null: false do
  argument :id, ID, required: false
  argument :external_id, ID, required: false
end

def car(id: :unspecified, external_id: :unspecified)
  if (id == :unspecified && external_id == :unspecified) || (id != :unspecified && external_id != :unspecified)
    raise GraphQL::ExecutionError.new('Must specify exactly one of id or externalId')
  end

  # ...
end

[RobsonKing]

ok, that is what I fell back to as well.

[rmosolgo]

Yep, best bet now is runtime, as shown above.

[blairio]

@RobsonKing oneOf is now a thing: #4184