Strategies for incorporating additional typings into an existing set

As a novice in typescript, I find myself delving into express and typescript and encountering the need to access req.id within a middleware function.

Unfortunately, attempting to do so results in this error message:

Property 'id' does not exist on type 'Request<ParamsDictionary, any, any, ParsedQs>'

This is the code snippet I am currently using:

app.use(function (req, res, next) {
  var log = logger.child(
    {
      id: req.id,
      body: req.body,
      params: req.params,
    },
    true
  );

  log.info({ req: req });
  next();
});

For now, I have been resorting to suppressing typescript errors with //@ts-ignore comments.

Additionally, I would appreciate any guidance on how to extend types in modules/packages to combat similar issues that may arise in the future.

typescriptexpress

Answer №1

Big thanks to @Linda for pointing me in the right direction. I was able to resolve this issue by incorporating custom type stubs. This concept is known as Module Augmentation within typescript

To implement, start by creating a new file named types.d.ts (used for module declaration)

import "express"; // this import is necessary to extend the type

declare module 'express' { 
  interface Request {
    id: string; // by adding this line, a new property of type string is introduced (accessible through `req.id`)
  }
}

Answer №2

Dealing with the types in express can be quite challenging due to the involvement of multiple packages, but after some effort I finally identified the specific one that needs to be extended. All we have to do is declare the single property we are adding, as this definition will merge with the existing one instead of replacing it entirely.

declare module "express-serve-static-core" {
    interface Request {
        id: number;
    }
}

Playground Link

This modification enables us to easily retrieve req.id.

Please keep in mind that an error may occur when calling next(), as next could potentially be undefined.

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Challenges encountered while using TypeScript to implement the CSS breakpoint mixin

I attempted to replicate the breakpoint mixin functionality described at using TypeScript, but I am having trouble correctly typing the function. import { css } from 'styled-components'; import { breakpoints } from './_variables'; exp ...

reactjstypescriptmixins

Node.js fetching twice the number of entries from MongoDB

const express = require('express'); const router = express.Router(); const Product = require('../models/products'); /* Fetching data from the database */ router.get('/', function(req, res, next) { const products = Product.f ...

node.jsmongodbexpressmongoose

Placing text inside a fixed-width container using the CSS property "white-space: pre;"

Let me clarify if the title seems unclear. I am developing a Q&A application using NodeJS, MongoDB, and Express. Currently, I am working on the layout using CSS. There is a small textarea where users can submit text. Upon clicking the submit button, ...

cssnode.jsexpressviewpug

Definition of Typescript:Named Function Expression (NFE)

In my current project, I am examining the JS code snippet below as part of creating a .d.ts file: BatchBuffer.js var Buffer = function(size) { this.vertices = new ArrayBuffer(size); /** * View on the vertices as a Float32Array for posi ...

typescript

Can you explain how parameters are being transferred to the onClick function?

While examining some code, I noticed the following snippet: <temp onClick={this.onSelected} /> The onSelected function appears to be defined like this: onSelected = (id: string) => { [...] } I'm curious how the id: string is being pas ...

javascriptreactjstypescript

Invoker of middleware and stack functions for Express.js with a focus on capturing the response object

It appears that the expressjs app contains a stack of Layer object Arrays. What function is utilized to pass the I am curious about: When a request is sent from the http client, which function is called first and how are the stack array functions with mi ...

javascriptnode.jsexpress

Are you encountering issues with Google Analytics performance on your Aurelia TypeScript project?

I recently started using Google Analytics and I am looking to integrate it into a website that I'm currently building. Current scenario Initially, I added the Google Analytics tracking code to my index.ejs file. Here is how the code looks: <!DOC ...

typescriptgoogle-analyticsaurelia

Steps for removing an item from an array in MongoDB

Is it possible to remove an object from the mainList array? _id:ObjectId("5fafc5aec2b84c301845c55a"), username:"test", mainList:[ { _id:ObjectId("5fafdf1a5b49510c789af0ae"), n ...

javascriptmongodbexpressmongoose

What is the best way to switch from using 'arguments' in JavaScript to Typescript?

I have a situation where I need to implement a method that gets called whenever the push operation is performed on an array. How should I approach this in typescript? My attempt so far: addEvent(myArray) { let _this = this; myArray.push = functi ...

javascripttypescript

Searching with two foreign keys in mongoose using Findby()

I managed to retrieve all the data from my 'someTable' using the "find()" method. someTable [ { "_id": "5e029b3ca7e71e06464c4c35", "someitem": "somedata1", "user": { "_id": "5de18423bddb7c058f97d57b" ...

node.jsmongodbexpressmongoose

Setting default values on DTO in NestJS can be done by using the DefaultValue decorator provided

import { IsString, IsNumber, IsOptional, IsUUID, Min, Max } from 'class-validator'; import { Transform } from 'class-transformer'; export class QueryCollateralTypeDto { @Transform(({ value }) => parseInt(value)) @IsNumber() @I ...

node.jstypescriptvalidationnestjsdefault

Error: Module not found in Visual Studio TypeScript

I am currently utilizing Visual Studio Professional 2015 to work on an application that incorporates Angular 4, TypeScript, and Webpack. Our team's goal was to enable the ability to import from both directories and files. For instance, within our pro ...

visual-studiotypescriptmoduletypescript-typings

Issue with the proper functionality of the this.formGroup.updateValueAndValidity() method in Angular 6

Currently, I am facing an issue where I need to add or remove validators in a formGroup's controls based on certain conditions. When I try to update the validators using `formGroup.updateValueAndValidity()` for the entire form, it does not seem to wor ...

angulartypescriptform-controlformgroupsangular-validator

Determine the data type of an individual attribute within a collection of classes

I am working with a series of classes that have a body property defined within them. Here is an example: class Foo { body: {foo: string} constructor(body: Record<string, string>) { this.body = { foo: body.foo } } } class Bar { body: {ba ...

typescript

Tips for disentangling code from types in Typescript

Instead of intertwining code and types like the example below: const compar8 : boolean | error = (action: string, n: number) => { switch(action) { case 'greater': return n > 8; case 'less': ...

javascripttypescripttypestypescript-typingstranspiler

Experiencing difficulties when trying to set up the express/body-parser node js eclipse

I'm currently working my way through the instructions for setting up express web servers using the eclipse/node js plugin in a tutorial book, and I am struggling to install express or create the necessary subfolders as instructed. Despite following th ...

node.jseclipseexpressnpm

Uncover the mystery behind the return value of a generic function in TypeScript

I can't seem to wrap my head around why TypeScript is behaving in the way described below. Snippet 01| const dictionary: { [key: string]: unknown} = {} 02| 03| function set<T>(key: string, value: T): void { 04| dictionary[key] = value; 05| } ...

typescript

Specifying the return type of a function as a combination of the types of the input arguments

Is there a way to safely implement the given function in TypeScript without using unsafe casts or an extensive number of function overloads with various input permutations? interface Wrapped<T> { type: string; data: T; } interface WrappedA&l ...

typescripttypescript-typingstypescript-generics

I am looking to dynamically print countries from an array in my code based on the selected option

I'm in need of some simple code assistance. I want to display a list of countries that correspond to a selected letter, but I'm struggling to do so dynamically at the moment. For example, if I select the letter A from a dropdown menu, I want the ...

javascriptangulartypescript

When using decorators with a singleton class in NodeJS, the initial state of the class is not retained

In my code, there is a class called MongoQueryResolver that includes a dictionary: private queries: {[key: string]: (params) => any} = {}; This dictionary stores functions by keys, where each function serves as a query function for MongoDB. To represe ...

node.jsexpressdecorator