I have the following utility function that is just a singleton class for storing a counter.
export class CounterSingleton {
private static instance: CounterSingleton;
private count: number;
private constructor() {
this.count = 0;
}
public static getInstance(): CounterSingleton {
if (!CounterSingleton.instance) {
CounterSingleton.instance = new CounterSingleton();
}
return CounterSingleton.instance;
}
public increment(): void {
this.count++;
}
public getCount(): number {
return this.count;
}
}
I want the counter class instance to be accessible within api routes. I have no problem with this.
// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
import { CounterSingleton } from "@/utility/counter";
import type { NextApiRequest, NextApiResponse } from "next";
type Data = {
counter: number;
};
export default function handler(
req: NextApiRequest,
res: NextApiResponse<Data>
) {
const counter = CounterSingleton.getInstance();
counter.increment();
res.status(200).json({ counter: counter.getCount() });
}
First api call: { counter: 1 }
Second api call: { counter: 2 }
When i access the same counter class within the middleware. It always gives me counter as 0.
import { NextResponse } from "next/server";
import { CounterSingleton } from "./utility/counter";
export function middleware() {
const counter = CounterSingleton.getInstance();
console.log(counter.getCount());
return NextResponse.next();
}
Can someone explain to me why is the singleton instance different in middleware?
