CRUD JSON API over a persistent Map: notes with title + body

soma.toml

[package]
name = "web-corpus"
version = "0.1.0"
entry = "todo_state.cell"

[verify]
cells = ["TodoService"]
deadlock_free = true
eventually = ["Done", "Cancelled"]

notes_crud.cell

// CRUD JSON API over a persistent Map: notes with title + body.
// Returns Maps directly (auto-serialized to JSON) and 404 responses on miss.
//   curl -X POST localhost:8080/api/notes -d '{"title":"hi","body":"world"}'

cell Notes {
    face {
        signal request(method: String, path: String, body: String) -> Map
        signal create(data: Map) -> Map
        signal read(id: String) -> Map
        signal update(id: String, data: Map) -> Map
        signal remove(id: String) -> Map
        signal index() -> List
        promise all_persistent
    }

    memory {
        notes: Map<String, Map> [persistent, consistent]
    }

    on create(data: Map) {
        let id = to_string(next_id())
        let note = map("id", id, "title", data.title, "body", data.body)
        notes.set(id, note)
        return note
    }

    on read(id: String) {
        let raw = notes.get(id)
        if raw == () { return response(404, map("error", "not found")) }
        return raw
    }

    on update(id: String, data: Map) {
        let raw = notes.get(id)
        if raw == () { return response(404, map("error", "not found")) }
        let title = data.title ?? raw.title
        let body = data.body ?? raw.body
        let note = map("id", id, "title", title, "body", body)
        notes.set(id, note)
        return note
    }

    on remove(id: String) {
        let existed = notes.delete(id)
        if existed == false { return response(404, map("error", "not found")) }
        return map("deleted", id)
    }

    on index() {
        return notes.values
    }

    on request(method: String, path: String, body: String) {
        let req = map("method", method, "path", path)
        match req {
            {method: "GET",    path: "/api/notes"}        -> index()
            {method: "POST",   path: "/api/notes"}        -> create(from_json(body))
            {method: "GET",    path: "/api/notes/" + id}  -> read(id)
            {method: "PUT",    path: "/api/notes/" + id}  -> update(id, from_json(body))
            {method: "DELETE", path: "/api/notes/" + id}  -> remove(id)
            _                                             -> response(404, map("error", "no route"))
        }
    }
}

cell test NotesTest {
    rules {
        assert create(map("title", "a", "body", "one")).title == "a"
        assert create(map("title", "b", "body", "two")).id == "2"
        assert read("1").body == "one"
        assert update("1", map("title", "z")).title == "z"
        assert update("1", map("title", "z")).body == "one"
        assert remove("2").deleted == "2"
        assert len(index()) == 1
    }
}