vapor-docs/3.0/docs/http/response.md

HTTP Response

When a client connects with an HTTP Server it sends a Request. This HTTP request will be processed as discussed here and resolved into a Response. This is the response in the http Request/Response model.

HTTP's Response object contains a Status, Headers and a Body. Before further reading this page, you must have read and understood the previous pages for Status, Headers and Body.

Responses are Extensible.

Creating a Response

A Response accepts a version, status, headers and body. The version's default is recommended. The body is optional.

The body can be a Body or BodyRepresentable. If the body is a BodyRepresentable the Response initializer will become throwing.

let response1 = Response(
                  status: status,
                  headers: headers,
                  body: body)

let response2 = try Response(
                  status: status,
                  headers: headers,
                  body: bodyRepresentable)

ResponseRepresentable

Instead of requiring a Response, many parts of the framework and related libraries work with the protocol ResponseRepresentable. When types conform to ResponseRepresentable they're required to implement a makeResponse function that allows conversion from this instance to a Response.

For the purpose of an example, we'll convert an integer to a Response. This Int will always response with a status code 200 (OK) and a body containing itself in textual representation.

extension Int: ResponseRepresentable {
  public func makeResponse() throws -> Response {
    return try Response(status: .ok, body: self.description)
  }
}

ResponseInitializable

ResponseInitializable is used for converting a Response to another type.

This is particularely useful for HTTP Clients that interact with existing APIs.

This example is pseudocode for interacting with a payment API such as Stripe or PayPal in a type-safe fashion.

struct PaymentStatus: ResponseInitializable {
  public init(response: Response) throws {
    // Create a `PaymentStatus` from the API call's `Response`
  }
}