# `AshTypescript.TypedChannel`
[🔗](https://github.com/ash-project/ash_typescript/blob/v0.17.3/lib/ash_typescript/typed_channel.ex#L5)

Standalone Spark DSL for typed Phoenix channel event subscriptions from
Ash PubSub publications.

Declares which publications a channel intercepts, enabling AshTypescript to
generate typed TypeScript payload types and a subscription helper for each
channel. The developer owns authorization (via `join/3`).

Publications should use `transform :some_calc` to reference a resource
calculation. When the calculation uses `:auto` typing, Ash automatically
derives the `returns` type from the expression, giving AshTypescript the
type information it needs without manual `returns` declarations. You can
also use explicit `returns:` with an anonymous function transform.

Register typed channels in application config:

    config :ash_typescript,
      typed_channels: [MyApp.OrgAdminChannel]

## Usage

    # Resource with calculation transforms (recommended)
    defmodule MyApp.Post do
      use Ash.Resource, notifiers: [Ash.Notifier.PubSub]

      pub_sub do
        module MyApp.Endpoint
        prefix "posts"

        publish :create, [:id], event: "post_created", public?: true, transform: :post_summary
        publish :update, [:id], event: "post_updated", public?: true, transform: :post_summary
      end

      calculations do
        calculate :post_summary, :auto, expr(%{id: id, title: title}) do
          public? true
        end
      end
    end

    # Channel definition
    defmodule MyApp.OrgAdminChannel do
      use AshTypescript.TypedChannel

      typed_channel do
        topic "org_admin:*"

        resource MyApp.Post do
          publish :post_created
          publish :post_updated
        end

        resource MyApp.Comment do
          publish :comment_created
        end
      end
    end

### Options

* `:extensions` (list of module that adopts `Spark.Dsl.Extension`) - A list of DSL extensions to add to the `Spark.Dsl`

* `:otp_app` (`t:atom/0`) - The otp_app to use for any application configurable options

* `:fragments` (list of `t:module/0`) - Fragments to include in the `Spark.Dsl`. See the fragments guide for more.

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*Consult [api-reference.md](api-reference.md) for complete listing*