Extend Express Request object using Typescript

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I’m trying to add a property to express request object from a middleware using typescript. However I can’t figure out how to add extra properties to the object. I’d prefer to not use bracket notation if possible.

I’m looking for a solution that would allow me to write something similar to this (if possible):

app.use((req, res, next) => {
    req.property = setProperty(); 
    next();
});

You want to create a custom definition, and use a feature in Typescript called Declaration Merging. This is commonly used, e.g. in method-override.

Create a file custom.d.ts and make sure to include it in your tsconfig.json's files-section if any. The contents can look as follows:

declare namespace Express {
   export interface Request {
      tenant?: string
   }
}

This will allow you to, at any point in your code, use something like this:

router.use((req, res, next) => {
    req.tenant = 'tenant-X'
    next()
})

router.get('/whichTenant', (req, res) => {
    res.status(200).send('This is your tenant: '+req.tenant)
})

Extend Express's Request Object with Typescript Declaration , Express has been my go to server side node web framework for the past few years. Its fast, unopiniona Tagged with node, express,  Next, I wrote a small NodeJS server using ExpressJS to understand basic concepts when working with Typescript and third-party packages. ⚫️ Good, everything works fine. The editor does not highlight any errors.

As suggested by the comments in the index.d.ts, you simply declare to the global Express namespace any new members. Example:

declare global {
  namespace Express {
    interface Request {
      context: Context
    }
  }
}
Full Example:
import * as express from 'express';

export class Context {
  constructor(public someContextVariable) {
  }

  log(message: string) {
    console.log(this.someContextVariable, { message });
  }
}

declare global {
  namespace Express {
    interface Request {
      context: Context
    }
  }
}

const app = express();

app.use((req, res, next) => {
  req.context = new Context(req.url);
  next();
});

app.use((req, res, next) => {
  req.context.log('about to return')
  res.send('hello world world');
});

app.listen(3000, () => console.log('Example app listening on port 3000!'))

Extending global namespaces is covered more at my GitBook.

How to extend the ExpressJS Request object with Typescript ‍ , Recently I've started working on a new NodeJS project. We have an incredibly big team that consists of one person. I have rich experience in frontend  Lets take a look at a typical Express middleware. The above code is an Express middleware that is used to ensure that a user is authenticated when he or she tries to access a protected resource. It decodes the user's token from the authorization property of the request headers and attaches the user to the Request object.

For newer versions of express, you need to augment the express-serve-static-core module.

This is needed because now the Express object comes from there: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/8fb0e959c2c7529b5fa4793a44b41b797ae671b9/types/express/index.d.ts#L19

Basically, use the following:

declare module 'express-serve-static-core' {
  interface Request {
    myField?: string
  }
  interface Response {
    myField?: string
  }
}

Extending express request/response objects in Typescript, It's useful to be able to provide a unified response “envelope” when creating a REST API. To do so with express for nodejs you can add custom  I'm trying to get the hang of TypeScript and various guides on how to use node.js and express talk about adding properties to the Request object before passing them down through the middleware. Of course, for type script these properties have to be defined so I tried to do so in a file called local.d.ts:

The accepted answer (as the others) does not works for me but

declare module 'express' {
    interface Request {
        myProperty: string;
    }
}

did. Hope that will help someone.

How to Extend Express when using Typescript, Make changes to the request and the response objects. End the request-​response cycle. Call the next middleware function in the stack. It will  Extend Express Request object using Typescript I’m trying to add a property to express request object from a middleware using typescript. However I can’t figure out how to add extra properties to the object.

None of the offered solutions worked for me. I ended up simply extending the Request interface:

import {Request} from 'express';

export interface RequestCustom extends Request
{
    property: string;
}

Then to use it:

import {NextFunction, Response} from 'express';
import {RequestCustom} from 'RequestCustom';

someMiddleware(req: RequestCustom, res: Response, next: NextFunction): void
{
    req.property = '';
}

Edit: Recent versions of TypeScript complain about this. Instead, I had to do:

someMiddleware(expressRequest: Request, res: Response, next: NextFunction): void
{
    const req = expressRequest as RequestCustom;
    req.property = '';
}

Extend Express Request and Response : Typescript Declaration , When we use TypeScript to Build a Node API with Express, you might Extending Request and Response Object with Declaration Merging. It simply means that at compilation the typescript compiler will merge separate type declarations into a single definition. Doing so will create an extended type, which will contain the properties of all the declarations together. Looking at the code above you would extend Express and ensure that the TS compiler knows about our customProperty. Create a new definition file in your project.

Extend Express Request object using Typescript, Extend Express Request object using Typescript. H_Developer Sep 28, 2019 750 0. Create a file custom.d.ts and make sure to include it in your tsconfig.json 's​  I want to let a piece of early middleware set a logging object on the request object, and use it later in the request handler flow. The middleware and the final request handler are organized in different files. What would be the best way to centrally extend the express.Request-object to allow using this logging object without having type warnings?

Extend Express Request object using Typescript - node.js - html, I'm trying to add a property to express request object from a middleware using typescript. However I can't figure out how to add extra properties to the object. Extend Express Request and Response : Typescript Declaration Merging When we use TypeScript to Build a Node API with Express, you might need to add some additional properties to the Express request and response object. To add extra properties to the request and response object you need to extend the response and request interface.

Can't extend express Request type · Issue #745 · TypeStrong/ts , string } } Example usage: import * as express from 'express' (req: express.​Request, res: express. can I make it work with ts-node? Versions: ts-node@7.0.​1 typescript@3.0.1 (req as any).something = object; it works for me  To add extra properties to the request and response object you need to extend the response and request interface. index.d.ts files are used to provide typescript type information about a module that’s written in JavaScript.For express, the index.d.ts is present inside the @types/express folder inside the node_modules folder.

Comments
  • you should be able to extend the request interface that the express.d.ts file provides with the fields you want.
  • I just did this, but I got it work without adding my custom.d.ts file to the files section in my tsconfig.json, yet it still works. Is this expected behavior?
  • @ChaimFriedman Yes. The files section restricts the set of files included by TypeScript. If you don't specify files or include, then all *.d.ts are included by default, so there's no need to add your custom typings there.
  • Not working for me: I get Property 'tenant does not exist on type 'Request' ` Doesn't make a difference if I explicitly include it in tsconfig.json or not. UPDATE With declare global as @basarat pointet out in his answear works, but I had to do import {Request} from 'express' first.
  • FWIW, this answer is now obsolete. JCM's answer is the correct way to augment the Request object in expressjs (4.x at least)
  • For future searches - a good example I found that worked out of the box: github.com/3mard/ts-node-example
  • Why is global needed in the declaration? What happens if its not there?
  • This works with interfaces, but in case anyone needs to merge types, note that types are "closed" and cannot be merged: github.com/Microsoft/TypeScript/issues/…
  • Mr @basarat I owe you some beers.
  • I also had to add to my tsconfig.json: { "compilerOptions": { "typeRoots": ["./src/typings/", "./node_modules/@types"] }, "files": [ "./src/typings/express/index.d.ts" ] }
  • None of the above solution worked.. but this one did the job in first run.. thanks a lot..!!
  • This worked for me, whereas extending the plain-old 'express' module did not. Thank you!
  • Was struggling with this, in order to get this to work, I had to import the module as well: import {Express} from "express-serve-static-core";