'Property `user` does not exist on type `Session & Partial<SessionData>`

I had a code in javascript and I'm trying to convert it to typescript

route.get('/order', async(req,res) => {  
    var sessionData = req.session;
    if(typeof sessionData.user === 'undefined')
    {        
        res.redirect('/panel/login');
    }

this is a piece of my code that used to work correctly in javascript but now I get this error for the user:

Property 'user' does not exist on type 'Session & Partial'

I assume I should add types for the sessionData variable and (req, res) params but I don't know what type should exactly be assigned to it.

PS: I know this question looks duplicated but I've tried solutions from other similar questions and it didn't work

any help would be appreciated.

Solution 1:^[1]

As stated in the express-session types comment, you have to use Declaration merging.

Here's how you can implement Declaration merging on express-session:

import session from 'express-session';

declare module 'express-session' {
  export interface SessionData {
    user: { [key: string]: any };
  }
}

Solution 2:^[2]

I just encountered the same issue as you. This seems to be a fairly recent issue: see explanation here.

To fix this I overloaded the module as described in the Github issue:

import "express-session";
declare module "express-session" {
  interface SessionData {
    user: string;
  }
}

Just replace string with whatever type you need for that field.

Also I have added ./typing-stubs in tsconfig.json

"typeRoots": [
      "./typing-stubs",
      "./node_modules/@types"
]

Solution 3:^[3]

i had this issue recently and here is the solution i came up with.

import { Request } from "express";
import { Session } from "express-session";

export type SessionWithUser = Session & { user: string | {}};

export type AuthRequest = Request & {
  session?: SessionWithUser;
  auth?: { user: string; permission_id: number };
};

Solution 4:^[4]

This is for future reference, for someone who have done all the step above but keep failing (vscode doesn't show the error anymore but still failed), it maybe ts-node problem, add --transpile-only to your package.json script, like this: nodemon --exec ts-node -T src/app.ts.

Source: Typescript Declaration Merging fail about Express Request

Solution 5:^[5]

Trace the source code you'll find such a comment:

    /**
     * This interface allows you to declare additional properties on your 
     * session object 
     * using [declaration merging] 
     * (https://www.typescriptlang.org/docs/handbook/declaration-merging.html).
     *
     * @example
     * declare module 'express-session' {
     *     interface SessionData {
     *         views: number;
     *     }
     * }
     *
     */
    interface SessionData {
        cookie: Cookie;
    }

Go ahead and read the documentation; you'll find a module augmentation section: https://www.typescriptlang.org/docs/handbook/declaration-merging.html#module-augmentation

Now, augment "SessionData" yourself and add "user" to it in: src/types/express-session/index.d.ts:

import { SessionData } from "express-session"

declare module "express-session" {
    interface SessionData {
        user: { [key: string]: any }
    }
}

Your tsconfig.json should set types roots to include the declaration in your compilation:

"typeRoots": ["./node_modules/@types", "./src/types"],

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1	Kapobajza
Solution 2	Rich
Solution 3
Solution 4	Phineas
Solution 5	Louis Huang

'Property `user` does not exist on type `Session & Partial<SessionData>`

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]