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

HTTPBody

HTTPBody is a type that contains the raw representation of a Request or Response. It's contents are related to the Content-Type header.

Body can contain, but is not limited to Data, String, DispatchData or binary streams. Binary streams will be chunk-encoded in HTTP/1.

Creating a Body

Empty bodies can be created using the empty initializer Body(). Alternatively you can provide Data or DispatchData as the content of the body.

HTTPBodyRepresentable

If you want to serialize your data to a body using a predefined format such as JSON or XML, look into Content first.

When adding a new struct/class that can be serialized to a raw Body as part of a Request or Response you can consider implementing the HTTPBodyRepresentable protocol.

Below is how String is implemented.

/// String can be represented as an HTTP body.
extension String: HTTPBodyRepresentable {
    /// See BodyRepresentable.makeBody()
    public func makeBody() throws -> HTTPBody {

    }
}

Although often unnecessary it is possible to throw an error here if the creation of the body failed.