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Codable support for APIGateway V2 request and response payloads #129

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Codable support for APIGateway V2 request and response payloads #129

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9abd4f9
Add APIGateway+V2+JSON
eneko Jun 14, 2020
b01b5e6
Provide extensions to decode and encode API Gateway V2 payloads
eneko Jun 14, 2020
ae03de0
Unit tests for payload coding/decoding
eneko Jun 14, 2020
bb688c4
Inject encoder and decoder
eneko Jun 15, 2020
7885a21
Merge branch 'master' into feature/codable-api-gateway-v2
eneko Jun 15, 2020
f24463b
PR Feedback. Fix tests.
eneko Jun 16, 2020
fda00d9
Merge branch 'feature/codable-api-gateway-v2' of https://github.com/e…
eneko Jun 16, 2020
536630d
Merge branch 'master' into feature/codable-api-gateway-v2
eneko Jun 17, 2020
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79 changes: 79 additions & 0 deletions Sources/AWSLambdaEvents/APIGateway+V2.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@
//
//===----------------------------------------------------------------------===//

import Foundation

extension APIGateway {
public struct V2 {}
}
Expand Down Expand Up @@ -117,3 +119,80 @@ extension APIGateway.V2 {
}
}
}

// MARK: - Codable Request body

extension APIGateway.V2.Request {
/// Generic body decoder for JSON payloads
///
/// Example:
/// ```
/// struct Request: Codable {
/// let value: String
/// }
///
/// func handle(context: Context, event: APIGateway.V2.Request, callback: @escaping (Result<APIGateway.V2.Response, Error>) -> Void) {
/// do {
/// let request: Request? = try event.decodedBody()
/// // Do something with `request`
/// callback(.success(APIGateway.V2.Response(statusCode: .ok, body:"")))
/// }
/// catch {
/// callback(.failure(error))
/// }
/// }
/// ```
///
/// - Throws: `DecodingError` if body contains a value that couldn't be decoded
/// - Returns: Decoded payload. Returns `nil` if body property is `nil`.
public func decodedBody<Payload: Codable>(decoder: JSONDecoder = JSONDecoder()) throws -> Payload? {
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rename Payload -> Body

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I wonder if instead of decoder: JSONDecoder = JSONDecoder() which should do something like decoder: (Body) -> String and have a default impl that uses JSONDecoder

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following on that line of thinking, @fabianfett maybe knows if this should be (Body) ->[UInt8], or String is good enough

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@eneko eneko Jun 16, 2020 •
edited
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The decoder should be either (String) throws -> Body or (String.UTF8View) throws -> Body, since we are decoding the content of the body property. Will update.

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@eneko eneko Jun 16, 2020 •
edited
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I've given this a shot, but kind of defeats the purpose of the pull request.

Here is what the extension would look like:

public func decodedBody<Body: Codable>(decoder: (String.UTF8View) throws -> Body) throws -> Body? {
    guard let utf8 = body?.utf8 else {
        return nil
    }
    return try decoder(utf8)
}

And what the callee would look like:

let decoder: (String.UTF8View) throws -> Body = { utf8 in try JSONDecoder().decode(Body.self, from: Data(utf8)) }
let body: Body? = try request.decodedBody(decoder: decoder)

At that point, using this extension would yield close to no benefit.

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@eneko I meant the library would offer a default impl as well, for example (non optimized):

public func decodedBody<Body: Decodable>(decoder: @escaping (String) throws -> Body = Self.jsonDecoder) throws -> Body? {
  try self.body.map(decoder)
}
        
public static func jsonDecoder<T: Decodable>(json: String) throws -> T {
  try JSONDecoder().decode(T.self, from: Data(json.utf8))
}

guard let bodyString = body else {
return nil
}
let data = Data(bodyString.utf8)
return try decoder.decode(Payload.self, from: data)
}
}

// MARK: - Codable Response body

extension APIGateway.V2.Response {
/// Codable initializer for Response payload
///
/// Example:
/// ```
/// struct Response: Codable {
/// let message: String
/// }
///
/// func handle(context: Context, event: APIGateway.V2.Request, callback: @escaping (Result<APIGateway.V2.Response, Error>) -> Void) {
/// ...
/// callback(.success(APIGateway.V2.Response(statusCode: .ok, body: Response(message: "Hello, World!")))
/// }
/// ```
///
/// - Parameters:
/// - statusCode: Response HTTP status code
/// - headers: Response HTTP headers
/// - multiValueHeaders: Resposne multi-value headers
/// - body: `Codable` response payload
/// - cookies: Response cookies
/// - Throws: `EncodingError` if payload could not be encoded into a JSON string
public init<Payload: Codable>(
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rename Payload -> Body

statusCode: HTTPResponseStatus,
headers: HTTPHeaders? = nil,
multiValueHeaders: HTTPMultiValueHeaders? = nil,
body: Payload? = nil,
cookies: [String]? = nil,
encoder: JSONEncoder = JSONEncoder()
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tbd.. same comment like the decoder above

) throws {
let data = try encoder.encode(body)
let bodyString = String(data: data, encoding: .utf8)
self.init(statusCode: statusCode,
headers: headers,
multiValueHeaders: multiValueHeaders,
body: bodyString,
isBase64Encoded: false,
cookies: cookies)
}
}
36 changes: 34 additions & 2 deletions Tests/AWSLambdaEventsTests/APIGateway+V2Tests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -68,10 +68,15 @@ class APIGatewayV2Tests: XCTestCase {
"x-amzn-trace-id":"Root=1-5ea3263d-07c5d5ddfd0788bed7dad831",
"user-agent":"Paw/3.1.10 (Macintosh; OS X/10.15.4) GCDHTTPRequest",
"content-length":"0"
}
},
"body": "{\\"some\\":\\"json\\",\\"number\\":42}"
}
"""

static let exampleResponse = """
{"isBase64Encoded":false,"statusCode":200,"body":"{\\"message\\":\\"Foo Bar\\",\\"code\\":42}"}
"""

// MARK: - Request -

// MARK: Decoding
Expand All @@ -86,6 +91,33 @@ class APIGatewayV2Tests: XCTestCase {
XCTAssertEqual(req?.queryStringParameters?.count, 1)
XCTAssertEqual(req?.rawQueryString, "foo=bar")
XCTAssertEqual(req?.headers.count, 8)
XCTAssertNil(req?.body)
XCTAssertNotNil(req?.body)
}

func testRquestPayloadDecoding() throws {
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typo

struct Payload: Codable {
let some: String
let number: Int
}

let data = APIGatewayV2Tests.exampleGetEventBody.data(using: .utf8)!
let request = try JSONDecoder().decode(APIGateway.V2.Request.self, from: data)

let payload: Payload? = try request.decodedBody()
XCTAssertEqual(payload?.some, "json")
XCTAssertEqual(payload?.number, 42)
}

func testResponsePayloadEncoding() throws {
struct Payload: Codable {
let code: Int
let message: String
}

let response = try APIGateway.V2.Response(statusCode: .ok, body: Payload(code: 42, message: "Foo Bar"))
let data = try JSONEncoder().encode(response)
let json = String(data: data, encoding: .utf8)
XCTAssertEqual(json, APIGatewayV2Tests.exampleResponse)
}

}