JSON

JSON plus Accept-based content negotiation. Foundation's Codable/JSONEncoder use runtime reflection, which is unavailable under Embedded Swift, so PlumeKit's JSON is a concrete value tree serialized and parsed by byte. It works identically on the native server and the Wasm worker.

JSONValue

let body = JSONValue.object([
    ("id", .int(1)),
    ("title", .string("Hello")),
    ("tags", .array([.string("a"), .string("b")])),
])
return .json(body)            // Response.json serializes it

JSONValue (null/bool/int/double/string/array/ordered-object) serializes byte-wise (escapes only what JSON requires; UTF-8 passes through) and parses via a recursive-descent parser. parseJSON(bytes)/parseJSON(string) returns a JSONValue?; read it with json["key"], .stringValue, .intValue, etc.

Two constraints from the Wasm build:

• No Double(String): it links strtod, absent in embedded wasm; numbers

are parsed by a byte-wise float routine (adequate for JSON, not bit-exact).

• No Unicode-aware String ops: keys compare and strings build/escape by byte.

Models ⇄ JSON (the ORM seam)

The @Model row codec is reused for JSON; there is no second codec:

post.jsonObject()              // { "id":1, "title":"…", "published":true, … }
jsonArray(posts)               // [ {...}, {...} ]
Post.fromJSON(request.json()!) // build from a client payload (by column name)

jsonObject() walks schema.columns + columnValues(); fromJSON maps a JSON object back into a Row by column name (absent keys → type defaults, so a payload without id is insert-ready).

Content negotiation

func index(_ request: Request) async throws -> Response {
    let posts = try await Post.all().all(in: request.bindings.database)
    if request.wantsJSON { return .json(jsonArray(posts)) }   // Accept: application/json
    return .text(/* … */)                                     // else HTML/text
}

request.wantsJSON (an Accept check), request.hasJSONBody (Content-Type), and request.json() (parse the body). A controller serves the same resource as JSON or HTML from one action.

Notes

Request and response bodies are buffered in memory, not streamed; keep very large payloads in object storage and pass references. NaN and the infinities have no JSON representation and encode as null.