Ash Elixir•3y ago

Autogenerated unique short IDs

What is the best way in Ash to generate short IDs e.g. invite codes that are unique and will keep generating till it gets a unique one? Actions?

14 Replies

ZachDaniel•3y ago

Yep! You can do it in a before action hook and check until you get a unique one 🙂

harryOP•3y ago

Check manually or does ash have checking built in?

ZachDaniel•3y ago

There is nothing that will repeatedly check and retry built in

harryOP•3y ago

👌🏼 So i write an action that generates then tryies to query for it, if it finds it -> generate a new one, else return

ZachDaniel•3y ago

Well, you’d just include that as a change on a create action.

harryOP•3y ago

yeah

ZachDaniel•3y ago

create :create do
  # assuming short_id is allow_nil: false, you'd use this to not require it for this action
  allow_nil_input [:short_id]

  change fn changeset, _ ->
    Ash.Changeset.before_action(changeset, fn changeset -> 
      Ash.Changeset.force_change_attribute(changeset, :short_id, generate_short_id(...))
    end)
  end
end

create :create do
  # assuming short_id is allow_nil: false, you'd use this to not require it for this action
  allow_nil_input [:short_id]

  change fn changeset, _ ->
    Ash.Changeset.before_action(changeset, fn changeset -> 
      Ash.Changeset.force_change_attribute(changeset, :short_id, generate_short_id(...))
    end)
  end
end

harryOP•3y ago

🔥 thanks yeah thats what I was plannin

iex(2)> Project.Resources.Invites.generate_code
[debug] QUERY OK source="invites" db=22.0ms idle=213.1ms
SELECT c0."id", c0."code", c0."sent_to", c0."max_uses", c0."created_at", c0."updated_at", c0."company_id" FROM "invites" AS c0 WHERE (c0."code"::text = $1::text) ["ExpDCJLb"]
↳ AshPostgres.DataLayer.run_query/2, at: lib/data_layer.ex:599
"ExpDCJLb"
iex(3)>

iex(2)> Project.Resources.Invites.generate_code
[debug] QUERY OK source="invites" db=22.0ms idle=213.1ms
SELECT c0."id", c0."code", c0."sent_to", c0."max_uses", c0."created_at", c0."updated_at", c0."company_id" FROM "invites" AS c0 WHERE (c0."code"::text = $1::text) ["ExpDCJLb"]
↳ AshPostgres.DataLayer.run_query/2, at: lib/data_layer.ex:599
"ExpDCJLb"
iex(3)>

  @alphabet Enum.concat([?0..?9, ?A..?Z, ?a..?z])
  @max_tries 15

  def generate_code(attempts \\ 1, len \\ 8) do
    code = for _ <- 1..len, into: "", do: <<Enum.random(@alphabet)>>

    with {:ok, []} <-
           Invite
           |> Ash.Query.for_read(:read)
           |> Ash.Query.filter(code == ^code)
           |> Project.Api.read() do
      code
    else
      _ ->
        if attempts > @max_tries do
          throw("failed to generate code")
        else
          generate_code(attempts + 1, len)
        end
    end
  end

  @alphabet Enum.concat([?0..?9, ?A..?Z, ?a..?z])
  @max_tries 15

  def generate_code(attempts \\ 1, len \\ 8) do
    code = for _ <- 1..len, into: "", do: <<Enum.random(@alphabet)>>

    with {:ok, []} <-
           Invite
           |> Ash.Query.for_read(:read)
           |> Ash.Query.filter(code == ^code)
           |> Project.Api.read() do
      code
    else
      _ ->
        if attempts > @max_tries do
          throw("failed to generate code")
        else
          generate_code(attempts + 1, len)
        end
    end
  end

Just putting the code here for anyone else :magic_sparkles:

ZachDaniel•3y ago

🥳

harryOP•3y ago

An optimisation would be checking for count rather than an actual query but idk if you can do that

ZachDaniel•3y ago

Not quite yet, but I'm working on Api.aggregate(query, :count, ...) to do exactly that

Terris•3y ago

This is a tangent but you might find this interesting. https://morioh.com/p/52d5efc4cba3

ExULID: Unique Lexicographically Sortable Identifier (ULID) in Elixir

In this tutorial, We'll learn ExULID: Universally Unique Lexicographically Sortable Identifier (ULID) in Elixir. Implemented according to ulid/spec.

harryOP•3y ago

They are a bit long for what I need xD thanks for sending though

Terris•3y ago

I know. The js ulid library I use lets you control the length and other aspects of the format. This elixir one is a bit deficient.

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Autogenerated unique short IDs

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