# \[Pre-pitch\] Roundtripping key coding strategies

**URL:** <https://forums.swift.org/t/pre-pitch-roundtripping-key-coding-strategies/52777>\
**Category:** Discussion\
**Tags:** codable, pitch\
**Created:** [October 13, 2021, 10:09am UTC](https://forums.swift.org/t/pre-pitch-roundtripping-key-coding-strategies/52777 "2021-10-13T10:09:23Z")\
**Posts on this page:** 1\
**Showing post:** 4

<div class="post-metadata">

**Author:** ![Morten\_Bek\_Ditlevsen](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/morten_bek_ditlevsen/32/28133_2.png) [@Morten\_Bek\_Ditlevsen](https://forums.swift.org/u/Morten_Bek_Ditlevsen)\
**Post date:** [October 13, 2021, 6:59pm UTC](https://forums.swift.org/t/pre-pitch-roundtripping-key-coding-strategies/52777/4 "2021-10-13T18:59:32Z")

</div>

A quick followup about the `AttributedString` `Codable` conformance:

It already doesn't play well with snake case key coding strategy:

```swift
let input = AttributedString("Hello").settingAttributes(.init([.imageURL : URL(string: "https://example.com/")!]))
print("Before: ", input)

let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase

let encoded = try! encoder.encode(input)
print("Encoded: ", String(data: encoded, encoding: .utf8)!)

let decoded = try! decoder.decode(AttributedString.self, from: encoded)
print("After: ", decoded)

```

Outputs the following:

```swift
Before: Hello {
	NSImageURL = https://example.com/
}
Encoded: ["Hello",{"n_s_image_url":{"relative":"https:\/\/example.com\/"}}]
After: Hello {
}

```

So it suffers from a similar (but not quite the same) issue as described above, but doesn't fail parsing - it just has an 'empty' attribute covering the "Hello" String.

I think that there may be some learning from this - I hope that I can formulate it clearly:

First of all my intuition about 'dynamic' keys still holds with this example: namely that it doesn't play well with key coding strategies.

Secondly: Is there a way to fix this? The only thing I can think of is a mechanism to explicitly opt-out from key coding strategies. You actually already get that when decoding dictionaries keyed by `String`s - the keys are left alone. I suspect that dictionary decoding wouldn't work in this case, however, but perhaps we can think of another way to opt out of the key coding? Another 'marker' protocol on `CodingKey`, perhaps?

---

_[View the full topic](https://forums.swift.org/t/pre-pitch-roundtripping-key-coding-strategies/52777)._