Ash.Error.Invalid.NoSuchInput on create

Ash Forum Ash Questions / Help
1

I’m starting to play with Ash, because I feel it will give me the DRYness of Rails and the clarity of Elixir & Phoenix. I roughly followed the Postgres how-to guide on the Ash framework website but I’m getting an error that I can’t explain, running this code:

Marketing.Lead
|> Ash.Changeset.for_create(:create, %{email: "mike@example.com", farmer: true})
|> Ash.create!()

This yields an error:

  (elixir 1.16.2) lib/process.ex:860: Process.info/2
  (ash 3.1.3) lib/ash/error/invalid/no_such_input.ex:5: Ash.Error.Invalid.NoSuchInput."exception (overridable 2)"/1
  (ash 3.1.3) lib/ash/changeset/changeset.ex:2034: anonymous fn/4 in Ash.Changeset.cast_params/4
   ...

I suspect it has something to do with the definition of my resource. Any ideas on how to figure out what’s causing this? Thank you for your time!

defmodule Marketing.Lead do
  use Ash.Resource, domain: Marketing, data_layer: AshPostgres.DataLayer

  postgres do
    table "leads"
    repo Muck.Repo
  end

  actions do
    defaults [:read]

    create :create
  end

  attributes do
    uuid_primary_key :id

    attribute :email, :string do
      allow_nil? false
    end

    attribute :farmer, :boolean do
      allow_nil? false
      default false
    end

    attribute :writer, :boolean do
      allow_nil? false
      default false
    end

    attribute :academic, :boolean do
      allow_nil? false
      default false
    end

    attribute :other, :string
  end
end
2

By default, an action does not accept any attributes as inputs. To resolve this, you have two options:

  1. Set an explicit accept list. this is the simplest
create :create do
  accept [:email, :farmer]
end
  1. Use :*, which means all public attributes

For example:

create :create do
  accept :*
end

...

attribute :email, :string do
  allow_nil? false
  public? true
end

attribute :farmer, :boolean do
  allow_nil? false
  public? true
end

This option is a bit more complex because public? affects other things like visibility over external APIs, etc.

3

Thank you Zach, that was exactly it! My mistake for overlooking that part of the Getting Started guide. It might be useful to make a minor change to the Getting Started guide:

    # and a create action, which we'll customize later
    create :create

…changing “customize” to something that indicates that adding accept with a list of attributes is not optional? Or maybe adding # accepts (list of attributes)?

Would it sense to have a more granular error, from “NoSuchInput” to “InputNotAccepted”, which would have likely lead me (and other future beginning Ash users) to the cause of the error?

I greatly appreciate all your work!

4

Yeah, I think updating the docs there is likely the best way to go, even just to indicate that we’ll be accepting things later, like

create :create do
  accept []
end

instead of just create :create would help with some of the confusion. I think we want to keep it to NoSuchInput because the type of error is used by things like api extensions to show error messages, and we want to make sure that its not possible for API extensions to leak internal resource details.

but, we can add “hints” that are in the error message on NoSuchInput, like “an attribute with this name exists, but is not accepted by the action. Perhaps you need to add it to the accept list of the action?”

If you could open issues or PRs for these two improvements, that would be wonderful :bowing_man:

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