Using `Ash.Type.String` like `Ash.Type.Enum`

What I'm imagining: lib/bookstore/types/isbn.ex:

defmodule Bookstore.Type.ISBN do
  use Ash.String, match: ~r/((978[\--– ])?[0-9][0-9\--– ]{10}[\--– ][0-9xX])|((978)?[0-9]{9}[0-9Xx])/
end

defmodule Bookstore.Type.ISBN do
  use Ash.String, match: ~r/((978[\--– ])?[0-9][0-9\--– ]{10}[\--– ][0-9xX])|((978)?[0-9]{9}[0-9Xx])/
end

lib/bookstore/resources/book.ex:

defmodule Bookstore.Book do
  alias Bookstore.Type
  attributes do
    attribute :isbn, ISBN
  end
end

defmodule Bookstore.Book do
  alias Bookstore.Type
  attributes do
    attribute :isbn, ISBN
  end
end

Seems like it would be good to be able to reuse and narrow many of the core types this way. Thoughts?

6 Replies

ZachDaniel•3y ago

I think that makes sense, but also keep in mind you can effectively do that with a custom type currently.

defmodule Bookstore.Type.ISBN do
  use Ash.Type

  def cast_input(value, constraints) do
    case Ash.Type.String.cast_input(value, constraints) do
      {:ok, type} -> 
        if String.match?(string, ~r//) do
        else
        end
    end
  end

  ...
end

defmodule Bookstore.Type.ISBN do
  use Ash.Type

  def cast_input(value, constraints) do
    case Ash.Type.String.cast_input(value, constraints) do
      {:ok, type} -> 
        if String.match?(string, ~r//) do
        else
        end
    end
  end

  ...
end

However, I see the value for what you're getting at up there. What I'd actually like to see is the ability to create a generic NewType (this is the term in most type systems). The NewType would simply package up some constraints on another type

defmodule Bookstore.Type.ISBN do
  use Ash.Type, type_of: :string, constraints: [match: ~r//]
end

defmodule Bookstore.Type.ISBN do
  use Ash.Type, type_of: :string, constraints: [match: ~r//]
end

Actually I really want that to exist, because that will help with many types. For example:

defmodule MyApp.Types.PositiveInteger do
  use Ash.Type, type_of: :integer, constraints: [min: 1]
end

defmodule MyApp.Types.PositiveInteger do
  use Ash.Type, type_of: :integer, constraints: [min: 1]
end

\ ឵឵឵OP•3y ago

That's right along my line of thought. This stuff can be accomplished using Ash.Type, but it would be great to have a more concise way to express a large portion of common cases.

ZachDaniel•3y ago

Honestly, its an easy change to make so I'm going to have a go at it 😄

\ ឵឵឵OP•3y ago

Awesome!

ZachDaniel•3y ago

This has been released as Ash.Type.NewType

\ ឵឵឵OP•3y ago

Great! Using it right now. It's a pleasure to work with a project that has responsive maintainers 👍

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Using `Ash.Type.String` like `Ash.Type.Enum`

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