Validator Middleware for Express

This is a simple validation middleware for Express.js that allows you to apply field validations on your route handlers. You can define validation rules in an easy-to-read object format, and the middleware will check the request's body (and req.params if needed) for errors before the route logic is executed.

Features

• Field-level validation with various rules (required, minLength, maxLength, email, etc.).
• Support for custom validation logic.
• MongoDB ID validation for routes that require an ID parameter (req.params.id).
• Error handling with clear messages for invalid fields.
• Easy integration into Express.js route handlers.

Installation

Here are the available validation rules you can use:

• required: Ensures the field is not empty.
• minLength: Ensures the field has at least the specified number of characters.
• maxLength: Ensures the field does not exceed the specified number of characters.
• min: Ensures the field value is greater than or equal to the specified number.
• max: Ensures the field value is less than or equal to the specified number.
• email: Validates if the field is a valid email address.
• pattern: Validates if the field matches a custom regular expression.
• numeric: Ensures the field value is a valid numeric value.
• boolean: Ensures the field value is a boolean.
• date: Ensures the field value is a valid date.
• decimal2: Ensures the field value has up to 2 decimal places.
• decimal6: Ensures the field value has up to 6 decimal places.
• custom: You can provide a custom validation function that returns true for valid - values or false for invalid values.

Example use

import express from "express";
import bodyParser from "body-parser";
import { validator } from "my-routes-validator";

const app = express();
app.use(bodyParser.json());

const options = {
  "/custom-validation": [
    {
      field: "username",
      message: "Username is required",
      required: true,
    },
    {
      field: "age",
      message: "Age must be a valid number and greater than 18",
      required: true,
      custom: (value) => !isNaN(value) && value > 18,
    },
    {
      field: "password",
      message: "Password must include at least one special character",
      required: true,
      custom: (value) => /[!@#$%^&*]/.test(value),
    },
    {
      field: "number",
      message:
        "Number must have up to two decimal places and up to six decimal places",
      required: true,
      decimal2: true,
      decimal6: true,
    },
  ],
};

app.post("/custom-validation", validator(options), (req, res) => {
  res.status(200).json({ message: "Validation passed!", data: req.body });
});

app.listen(3000, () => {
  console.log("Server is running on http://localhost:3000");
});

Installation

You can install this package via npm:

npm install my-routes-validator