Property '' does not exist on type 'Request<ParamsDictionary>'

Question

When trying to extend the Request interface from the package express to add some custom properties, I'm getting the following typescript error:

TS2339: Property '' does not exist on type 'Request<ParamsDictionary>'.

Do you know how to solve that?

Solution 1

Since a recent update of its typings and dependencies, I found that the following should fix the errors in your application.

In your tsconfig.json

{
  "compilerOptions": {
    //...
    "typeRoots": [
      "./custom_typings",
      "./node_modules/@types"
    ],
  }
// ...
}

And in your custom typings

// custom_typings/express/index.d.ts
declare namespace Express {
    interface Request {
        customProperties: string[];
    }
}

Solution 2

Just add the following, what this does is it simply adds a custom property to the express Request interface

declare global {
  namespace Express {
    interface Request {
      propertyName: string; //or can be anythin
    }
  }
}

Solution 3

I recently had the same issue, I followed the solution in the previous comments and this repo and I still had the same issue. After doing more digging it seems like it's a bug with ts-node.

To solve this you need to run your server with a --files flag

So if you normally run your server ts-node ./src/server.ts or nodemon ./src/server.ts Change it to ts-node --files ./src/server.ts or nodemon --files ./src/server.ts

After that, I was able to get rid of both the VScode errors and errors while starting the server.

Comments

[Rohit Ambre]

yeah, it does fix but when just created index.d.ts file on root folder my VScode stopped showing error but I was still getting error on terminal, so I did as you described but directly created index.d.ts file inside custom_typings and still it was giving error, it went after creating express folder, so why is that express folder mandatory ?

[oktapodia]

You can either create a directory named express or having a file named express.d.ts to tell typescript that you are aiming this specific module

[danish.ahmad]

@RohitAmbre did you figure out how to fix it. Vscode seems to have no issues but compiler showing some errors.

[Rohit Ambre]

@danie_man, I did like what I have explained in my comment and it works without any compiler issue you can check here

[Tank12]

Thank you for this, could you explain how this works a bit more? I've never seen someone use declare global