Use Siesta framework

Model/Store.swift

@@ -0,0 +1,19 @@
+import Foundation
+import Siesta
+
+final class Store<Data>: ResourceObserver, ObservableObject {
+    @Published private var all: Data?
+
+    var collection: Data { all ?? ([] as! Data) }
+    var item: Data? { all }
+
+    func resourceChanged(_ resource: Resource, event _: ResourceEvent) {
+        if let items: Data = resource.typedContent() {
+            replace(items)
+        }
+    }
+
+    func replace(_ items: Data) {
+        all = items
+    }
+}