Installed module 'express-validator' cannot be found in NodeJS/Express project-CodePudding

I want to validate the input that the endpoint receives upon invoking it. Therefore, I installed express-validator in my NodeJS web application. However, when I try to make use of it, it throws the error:

Cannot find module 'express-validator' or its corresponding type declarations

This happens, when I import it (i.e., import { validationResult } from "express-validator";) or set it as an constant and require it. In the latter, it states that it cannot find the module. I have dockerized the project and this is the the dockerfile I have set up:

FROM node:12

WORKDIR /app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 8000

CMD ["npm", "run", "dev"]

Currently, I am not running a production version, which is why I am running with dev. This is my docker-compose file:

services:
  db:
    image: postgres:12
    environment:
      - POSTGRES_DB=server_side
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=123321
  app:
    build:
      context: .
      dockerfile: Dockerfile
    volumes:
      - ./src:/app/src
    ports:
      - "8000:8000"
    depends_on:
      - db
    environment:
      - POSTGRES_DB=server_side
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=123321
      - POSTGRES_HOST=db

When installing the module, it gets added to my dependencies:

{
  "name": "Servier-side",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "tsc",
    "dev": "concurrently \"nodemon\" \"nodemon -x tsoa spec\"",
    "start": "node build/index.js",
    "predev": "npm run swagger",
    "prebuild": "npm run swagger",
    "swagger": "tsoa spec",
    "typeorm": "node --require ts-node/register ./node_modules/typeorm/cli.js",
    "migrate:generate": "npm run typeorm migration:generate -- -n",
    "migrate:run": "npm run typeorm migration:run",
    "migrate:revert": "npm run typeorm migration:revert",
    "schema:drop": "npm run typeorm schema:drop"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@types/express": "^4.17.13",
    "@types/morgan": "^1.9.3",
    "@types/node": "^16.11.10",
    "@types/swagger-ui-express": "^4.1.3",
    "concurrently": "^6.4.0",
    "nodemon": "^2.0.15",
    "ts-node": "^10.4.0",
    "typescript": "^4.5.2"
  },
  "dependencies": {
    "express": "^4.17.1",
    "express-validator": "^6.13.0",
    "morgan": "^1.10.0",
    "pg": "^8.7.1",
    "reflect-metadata": "^0.1.13",
    "swagger-ui-express": "^4.1.6",
    "tsoa": "^3.2.1",
    "typeorm": "^0.2.41"
  },
  "nodemonConfig": {
    "watch": [
      "src"
    ],
    "ext": "ts",
    "exec": "ts-node src/index.ts"
  }
}

I would really appreciate if someone could shed light on the matter. Just for the sake of excluding possible reasons, I also tried with Joi, but I ended up with the same issue. So, what I would like to understand is what is causing the issue - Why does is work for the rest of the dependencies and not this one and what should be done to resolve the issue?

CodePudding user response：

This kind of error is usually when you need to add the @types dependency for the module.

CodePudding user response：

Running docker compose with the build flag docker-compose up --build fixed the issue.