Supporting potential duplicate keys in JSON from a Foundation.Data

[rgoldberg]

@tayloraswift I looked into solutions for this issue again, then realized that I should use JSONDecodable instead of JSONObjectDecodable. I just assumed that the later would be preferred for objects & wouldn't be any more constrained than the former.

My app obtains JSON in a Foundation.Data from a network call.

I want to eventually output that JSON in a String, but with various object keys mapped to new values, while passing through all other keys as is.

I'm looking at swift-json because I want to support duplicate keys in the same object (which isn't supported by Foundation JSON processing, IIUC).

I don't expect to receive duplicate keys, but there is no formal spec for the JSON, and I am not in control of the server that provides the JSON.

I want to sort the keys after I've mapped them (preferably like localizedStandardCompare), but I want duplicate keys to remain in their original order relative to one another.

JSON.ObjectDecoder seems to expose only var index: [CodingKey: JSON.Node], which cannot support duplicate keys.

How should I decode supporting duplicate keys?

I assume that, if I decode use a [(JSON.Key, JSON.Node)] interface, JSON encoding will honor the order of the elements in the array (so I can affect the output by sorting the array).

I would presumably decode in an init(…) for a struct, as I need to extract a few properties from the JSON to determine what to do with various JSON & to output specific information about the JSON in some other places in my app. The init(…) would save the given JSON as a private let json: String property of the struct, then use the json property's value for the struct's var description: String, so that my app can output the JSON with mapped keys.

Any help will be appreciated.

Thanks for the library.

PS: it might be useful to list bullet points in the README.md providing reasons to use swift-json, including:

• Pure Swift (i.e. does not require Foundation or any other frameworks)
• High performance
• High throughput
• Supports duplicate JSON object keys
• Fast compilation
• Low file size cost
• ≤Such> style interface instead of Foundation's <other> style interface
• …