Ash

Quick Links

• Resource Documentation
• DSL Documentation

Introduction

Traditional MVC Frameworks (Rails, Django, .Net, Phoenix, etc) leave it up to the user to build the glue between requests for data (HTTP requests in various forms as well as server side domain logic) and their respective ORMs. In that space there is an incredible amount of boilerplate code that must get written from scratch for each application (authentication, authorization, sorting, filtering, pagination, sideloading relationships, serialization, etc). Often this code is untested, lacks many feature support, is tighly coupled to a specific web layer, and varies widely between each piece of data.

Ash is an opinionated yet configurable framework designed to reduce boilerplate in any Elixir application by providing a layer of abstraction over the data layer of your system called a Resource. Don't worry Phoenix developers - Ash is designed to play well with Phoenix :)

To riff on a famous JRR Tolkien quote, a Resource is "One Interface to rule them all, One Interface to find them, One Interface to bring them all, and in the darkness bind them".

First you declare your resources using the Ash resource DSL. You could technically stop there, and just leverage the Ash Elixir API to avoid writing boilerplate. More likely, you would use libraries like Ash.JsonApi or Ash.GraphQL(someday) with Phoenix to add external interfaces to those resources without having to write any extra code at all.

Developers shoud be focusing on their core business logic - not boilerplate code. Ash builds upon the incredible productivity of Phoenix and empowers developers to get up and running with a fully functional app in substantially less time, while still being flexible enough to allow customization when the need inevitably arises.

Ash is an open source project, and draws inspiration from similar ideas in other frameworks and concepts. The goal of Ash is to lower the barrier to adopting and using Elixir and Phoenix, and in doing so help these amazing communities attract new develpers, projects, and companies.

Example Resource

defmodule Post do
  use Ash.Resource, name: "posts", type: "post"
  use AshJsonApi.JsonApiResource
  use Ash.DataLayer.Postgres

  actions do
    read :default,
      authorization_steps: [
        allow_if: user_is(:admin)
      ]

    create :default,
      authorization_steps: [
        allow_if: user_is(:admin)
      ]
    
  end

  attributes do
    attribute :name, :string
  end

  relationships do
    belongs_to :author, Author
  end
end

TODO LIST (in no order)

• Make our router cabaple of describing its routes in mix phx.routes Chris McCord says that we could probably power that, seeing as phoenix controls both APIs, and that capability could be added to Plug.Router
• Finish the serializer
• Make primary key type configurable, and support composite primary keys
• Make a DSL for join tables to support complex validation/hooks into how they work, support more than just table names in join_through
• DSL level validations! Things like includes validating that their chain exists. All DSL structs should be strictly validated when they are created.
• Especially at compile time, we should never ignore or skip invalid options. If an option is present and invalid, an error is raised.
• break up the Ash module
• Wire up/formalize the error handling
• Ensure that errors are properly propagated up from the data_layer behaviour, and every operation is allowed to fail
• figure out the ecto schema warning
• all actions need to be performed in a transaction
• document authorization thoroughly. batch (default) checks need to return a list of ids for which the check passed.
• So many parts of the system are reliant on things having an id key explicitly. THis will need to be addressed some day, and will be a huge pain in the ass
• Validate that the user resource has a get action
• params should be solidified. Perhaps as a struct. Or perhaps just renamed to action_params where it is used.
• Since actions contain rules now, consider making it possible to list each action as its own do block, with an internal DSL for configuring the action. (overkill?)
• Validate rules at creation
• Maybe fix the crappy parts of optimal and bring it in for opts validation?
• The ecto internals that live on structs are going to cause problems w/ pluggability of backends, like the %Ecto.Association.NotLoaded{}. That backend may need to scrub the ecto specifics off of those structs.
• Add a mixin compatibility checker framework, to allow for mix_ins to declare what features they do/don't support.
  • Have ecto types ask the data layer about the kinds of filtering they can do, and that kind of thing.
• Make Ash.Type that is a superset of things like Ecto.Type. If we bring in ecto database-less(looking like more and more of a good idea to me) that kind of thing gets easier and we can potentially lean on ecto for type validations well.
• use a process to hold constructed DSL state, and then coalesce it all at the end. This can clean things up, and also allow us to potentially eliminate the registry. This will probably go hand in hand w/ the "capabilities" layer, where the DSL confirms that your data layer is capable of performing everything that your DSL declares
• make ets dep optional
• Bake in descriptions to the DSL
• Contributor guideline and code of conduct
• Do branch analysis of each record after authorizing it, in authorizer
• consider moving type and name for resources out into json api (or perhaps just name) since only json api uses that
• When we support embedding, figure out embed_as on Ash.Type
• Consider allowing declaring a data layer at the api level, or overriding the resource's data layer at the api level
• Since actions can return multiple errors, we need a testing utility to unwrap/assert on them
• Flesh out relationship options
• Flesh out field options (sortable, filterable, other behavior?)
• Unit test the Ets data layer
• Improve pagination in the ETS data layer
• Rearchitect relationship updates so that they can be sensible authorized. As in, which resource is responsible for authorizing updates to a relationship? Should there be some unified way to describe it? Or is updating a user's posts an entirely separate operation from updating a post's user?
• Test authorization
• Member specific authorization, defaulting to unauthorized
• Validate that all relationships on all resources in the API have destinations in that API, or don't and add in logic to pretend those don't exist through the API.
• Make authorization spit out informative errors (at least for developers)
• Use telemetry and/or some kind of hook system to add metrics
• Forbid impossible auth/creation situations (e.g "the id field is not exposed on a create action, and doesn't have a default, therefore writes will always fail.)