Proposal: Adding `RequestBehaviour`s to Malibu

[Robin]

Hey!

I've been reading about RequestBehaviour recently and I think it'd be a great addition to Malibu, especially for things like Logging, NetworkActivityIndicators, authentication, caching etc.

Here's what the protocol looks like

protocol RequestBehavior {

	func beforeSend()

	func afterSuccess(result: Any)

	func afterFailure(error: Error)

	func adapt(_ request: URLRequest) -> URLRequest

}

// default implementations
extension RequestBehavior {
	func beforeSend() {

	}

	func afterSuccess(result: Any) {

	}

	func afterFailure(error: Error) {

	}

	func adapt(_ request: URLRequest) -> URLRequest {
		return request
	}
}

And Auth can be implemented as follows:

struct TokenAuthBehaviour: RequestBehavior {
	let token: String

	func adapt(_ request: URLRequest) -> URLRequest {
		var copy = request
		var headers = copy.allHTTPHeaderFields ?? [:]
		headers["Authorization"] = "Bearer \(token)"
		copy.allHTTPHeaderFields = headers
		return copy
	}
}

struct CustomAuthBehaviour: RequestBehavior {

	let key: String
	let value: String

	func adapt(_ request: URLRequest) -> URLRequest {
		var copy = request
		var headers = copy.allHTTPHeaderFields ?? [:]
		headers[key] = value
		copy.allHTTPHeaderFields = headers
		return copy
	}
}

struct CustomAuthBehaviour: RequestBehavior {

	let key: String
	let value: String

	func adapt(_ request: URLRequest) -> URLRequest {
		var copy = request
		var headers = copy.allHTTPHeaderFields ?? [:]
		headers[key] = value
		copy.allHTTPHeaderFields = headers
		return copy
	}
}

There's other examples in the blog post, but this would be an excellent starting point (Logging could be in both before and after function calls, for example)

PS: Discussed this with @vadymmarkov on Twitter recently: https://twitter.com/vadymmarkov/status/956075029736894465

[Robin]

Another advantage to this approach is, you can compose Request Behaviours, making Malibu incredibly explicit!

struct CombinedRequestBehavior: RequestBehavior {

	let behaviors: [RequestBehavior]

	func adapt(_ request: URLRequest) -> URLRequest {
		return behaviors.reduce(request) { (req, behaviour) in
			return behaviour.adapt(req)
		}
	}

	func beforeSend() {
		behaviors.forEach({ $0.beforeSend() })
	}

	func afterSuccess(result: Any) {
		behaviors.forEach({ $0.afterSuccess(result: result) })
	}

	func afterFailure(error: Error) {
		behaviors.forEach({ $0.afterFailure(error: error) })
	}
}

[Vadym Markov]

I think it would be a great addition to the library. What are your thoughts @onmyway133 @zenangst ?

[Khoa]

@codeOfRobin @vadymmarkov Good idea. I see Malibu has customisation points where we can configure request already, but this is a nice refactoring around it.

[Robin]

I'll start working on some changes. Thank you for the feedback guys!

[Robin]

Hey folks! So sorry I’ve not been able to give it much thought over the past week + (Been dealing with some work stuff). Will get to this tomorrow 👍

[Robin]

Hey @vadymmarkov I've been considering retaining the beforeEach and preProcessRequest semantics in the RequestBehaviour protocol. Could you check this out and tell me what you think: codeOfRobin@51c6036

[Vadym Markov]

I think it should work @codeOfRobin