Request struct for internal using, convert data map from websocket api.

Data from websocket api has payload like this:

%{
  "request_id" => "request_id",
  "request_type" => "request_type",
  "service" => "service",
  "user_id" => "user_id",
  "device_id" => "device_id",
  "args" => %{}
}

We need to convert it to struct for internal using.

Like this:

%PhoenixGenApi.Structs.Request{
  request_id: "request_id",
  request_type: "request_type",
  service: "service",
  user_id: "user_id",
  device_id: "device_id",
  args: %{}
}

Explain:

• user_id: string, user's id in system. User's id in system. It need to check permission.

• device_id: string, device id of current connection. Device id of current connection.

• request_type: string, request type. Request type. Using for identify function to call in system.

• request_id: string, unique id for request. Make by client. Unique id for request. Make by client. Using for identify response.

• service: string, service name. Service name. Using for identify service to call in system.

• args: map, field -> value, arguments for request. Arguments for request. Using for call function in system.

Payload Size Validation

decode!/1 validates the payload size before deserialization to prevent memory exhaustion from oversized requests. The limit is configurable via application env:

config :phoenix_gen_api, :request,
  max_payload_bytes: 1_000_000  # default: 1MB

Use max_payload_bytes/0 to read the current configured limit at runtime.

Security Considerations

• Payload size is checked before deserialization to prevent memory exhaustion attacks where a client sends an enormous map.
• The default limit is 1MB and can be configured per application needs via config :phoenix_gen_api, :request, max_payload_bytes: N.
• The check uses :erlang.external_size/1 (when available) for accurate measurement without allocating the full binary. Falls back to byte_size(:erlang.term_to_binary(params)) on older Erlang/OTP releases.
• If the payload exceeds the limit, decode!/1 raises an error with the configured maximum and the actual measured size.