RequestsCombine

Requests is a set of protocols and Combine publishers that makes integrating network requests easy. It uses a declarative style of defining a request, its result type, error type, as well as constructing the URLRequest and processing the data received, all in a single file. These requests can then be instantiated, configured, and will vend a publisher to execute the network request.

This enables testing the construction of a network request separately from how it is executed. The URLRequest construction, data processing, and error mapping can all be tested separately without a network connection or mocked URLSession.

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Installation

Install using the Swift Package Manager.

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Documentation

Request

Request is the base protocol, which defines the Success/Failure types, a factory method to construct a URLRequest, and a function to map any upstream Errors to the Request's Failure type.

DataRequest returns the raw data received by the network request. Implementors are free to do whatever they need to in order to transform the data to the desired Success type.

DecodableRequest allows for direct deserialization of Decodable objects, and also declares a makeDecoder() func to provide a custom JSONDecoder.

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Usage

• Create a request type that conforms to DataRequest or DecodableRequest
• Specify the Success/Failure typealiases
• Implement makeURLRequest()
• If you are implementing DataRequest directly, implement processData(), otherwise DecodableRequest provide a default implementation of this method

Example:

struct Recipe: Decodable {
    let name: String
    let ingredients: [String]
    let steps: [String]
}

struct RecipeRequest: DecodableRequest {
    typealias Success = Recipe
    typealias Failure = Error

    let recipeId: String

    func makeURLRequest() -> Void {
        let url = URL(string: "https://recipes.com/fakeapi/recipe/\(recipeId)")!
        let urlRequest = URLRequest(url: url)
        return urlRequest
    }
}

Now you have a RecipeRequest that returns a Recipe on success, execute it by creating a publisher and calling sink():

var cancellables: Set<AnyCancellable> = []

let request = RecipeRequest(recipeId: "1")
request.publisher().sink { result in
    if case let .failure(error) = result {
        print(error)
    }
} receiveValue: { recipe in
    print("Recipe name: \(recipe.name)")
}.store(in: &cancellables)