Is this Int64 Swift Decoding superfluous?-CodePudding

I have seen a piece of code online which uses Swift Codable do decode a JSON into a struct.

init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    if let stringValue = try? container.decode(String.self, forKey: .someId), let value = Int64(stringValue) {
        someId = value
    } else {
        someId = try container.decode(Int64.self, forKey: .someId)
    }
}

This code:

decodes a string
tries to parse it into Int64
if it fails - it directly attempts to decode an Int64

My question is - is this code superfluous?

Is there any scenario where Int64.init(_:) from String would be able to decode something that JSONDecoder.decode wouldn't?

And actually, isn't this "decode String - init Int64" the exact same thing that JSONDecoder does under the hood?

CodePudding user response：

It is not superfluous. It could be used to handle JSON that sometimes has numbers encoded as a string (within quotes), and sometimes just as a number.

For example, the JSON could sometimes be:

{
    "someId": "12345"
}

in which case you need to decode to String, and then Int64.init

And sometimes the JSON could be:

{
    "someId": 12345
}

in which case decoding to String would fail, and you would directly decode to Int64.