Update

src/server/api.ts

@@ -75,16 +75,15 @@ export default function (server, opts, done) {
     if (req.params.id == undefined)
       return reply.code(400).send({ error: "No ID query parameter" });
 
-    server.level.db.put(req.params.id, req.body, (err) => {
-      if (err) {
-        console.warn(err);
-        reply.code(500).send({ error: "Error with DB" });
-      } else {
-        reply.send({ content: "ok" });
-      }
-    });
-    return reply;
-  });
+    return server.level.db.get(req.params.id).then(r=>r.version||-1).catch(_=>-1).then(db_version=>{
+      if(db_version+1 == req.body.version)
+        return server.level.db.put(req.params.id, req.body)
+          .then(_=>reply.send({ content: "ok" }))
+          .catch(_=>reply.code(500).send({ error: "Error with DB" }))
+        
+      return reply.code(409).send({error:"Too old version, please refresh."});
+      })
+  })
 
   done();
 };