Parse Swift can't decode custom ParseCloud errors

[dblythy]

Throwing a custom error code from a Parse Cloud function results in:

ParseError(code: ParseSwift.ParseError.Code.unknownError, message: "Error decoding parse-server response: Optional(<NSHTTPURLResponse: 0x100d74140> { URL: http://localhost:1337/1/jobs/test } { Status Code: 200, Headers {\n    \"Content-Type\" =     (\n        \"application/json\"\n    );\n} }) with error: The data couldn’t be read because it is missing. 

Failing case:

    func testCustomError() {

        let encoded: Data = "{\"error\":\"Error: Custom Error\",\"code\":2000}".data(using: .utf8)!

        MockURLProtocol.mockRequests { _ in
            return MockURLResponse(data: encoded, statusCode: 200, delay: 0.0)
        }
        do {
            let cloud = Cloud(functionJobName: "test")
            _ = try cloud.startJob()
            XCTFail("Should have thrown ParseError")
        } catch {
            if let error = error as? ParseError {
                XCTAssertNotEqual(error.code, ParseError.Code.unknownError)
                XCTAssertEqual(error.code.rawValue, 2000)
            } else {
                XCTFail("Should have thrown ParseError")
            }
        }
    }

Proposed solution:

Add .other enum to error, and intCode property to Parse.Error

[cbaker6]

@dblythy thanks for your PR! Here’s a response I gave to a similar proposal? #106 (comment)

From your addition, does this mean the other SDKs currently allow users to create their own errors and mask them as Parse errors? I could be wrong here, but I would think errors would come from a set list of known Parse errors. If a user generates an error, maybe it can fall under “unknownError” or add a new error code on the server specific to user errors? Not sure what’s the best approach, but definitely open to hear you and the servers team thoughts.

My fear is allowing developers to mask their errors as parse errors and then people submit issues to Parse repos claiming they are Parse errors when they are not

[cbaker6]

My reasoning of using unknownError is because of how Flo documented ParseError before I took over it:

Parse-Swift/Sources/ParseSwift/Types/ParseError.swift

Lines 35 to 37 in 603486a

	Internal SDK Error. No information available
	*/
	case unknownError = -1

It seems believed all SDK errors, technically custom SDK errors should fall under this error. So I can see other errors going here as well

[dblythy]

The main problem is that if you use a custom error, (which is already supported in Parse Server as well as every other SDK) Parse Swift can't decode it.

Such as:

Parse.Cloud.define("runFunction", ({user}) => {
  if (user.get('trialExpired')) {
     throw new Parse.Error(9000, "Your trial has expired");
  }
  ...
});

Call function:

if (e.code === 9000) {
// redirect to upgrade page
}

parse-community/docs#943

[cbaker6]

If I understand the discussion you linked it’s proposing to restrict custom errors to a specific range? parse-community/docs#943

That seems reasonable I guess and prevent some of my concern above

[dblythy]

The discussion linked is more to highlight that throwing specific custom errors from Cloud Code or third party modules is a common use case.

The main use for me is to change the behaviour of the app based on the custom error code response from the Parse Server.

[dblythy]

Furthermore:

https://github.com/parse-community/parse-server/blob/10695194b21a3ae2d34f88704a50a5ac0890202c/spec/CloudCode.spec.js#L143

[dblythy]

FYI to anyone hoping to use this, you can use ParseError.otherCode if you are throwing custom Parse Errors from Parse Cloud