# `AsyncApiSpex.Message`
[🔗](https://github.com/jamescarr/ankusa/blob/async_api_spex-v0.2.0/packages/async_api_spex/lib/async_api_spex/message.ex#L1)

A message on a channel: its metadata, headers, and payload.

`payload` and `headers` are AsyncAPI Schema Objects, which may be plain maps,
`%AsyncApiSpex.Reference{}` structs, or modules that export
`__async_api_schema__/0`. A module is extracted into `components.schemas` by
`AsyncApiSpex.resolve/1` and replaced with a reference.

Use the `use AsyncApiSpex.Message` macro to declare a message:

    defmodule MyApp.Messages do
      use AsyncApiSpex.Message,
        name: "OrderCreated",
        payload: MyApp.Schemas.OrderCreatedV1
    end

This defines `message/0` returning a `%AsyncApiSpex.Message{}` and
`__async_api_message__/0` returning `{name, message}`.

# `t`

```elixir
@type t() :: %AsyncApiSpex.Message{
  bindings: map() | nil,
  content_type: String.t() | nil,
  correlation_id: AsyncApiSpex.CorrelationId.t() | nil,
  description: String.t() | nil,
  examples: [term()] | nil,
  extensions: map(),
  headers: map() | AsyncApiSpex.Reference.t() | module() | nil,
  name: String.t() | nil,
  payload: map() | AsyncApiSpex.Reference.t() | module() | nil,
  summary: String.t() | nil,
  tags: [AsyncApiSpex.Tag.t()] | nil,
  title: String.t() | nil
}
```

# `__using__`
*macro* 

Declares a message on the calling module.

Options: `[:title, :summary, :description, :content_type, :payload, :headers, :correlation_id, :tags, :bindings, :examples, :extensions]` plus the required `:name` (a
string matching `~r/\A[A-Za-z0-9_.-]+\z/`). Unknown options raise
`ArgumentError`. The option values are evaluated in the calling module's
context.

---

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