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  3. hapi — Request Payload Validation With Joi

hapi — Request Payload Validation With Joi

Within last week’s tutorial you’ve learned how to access the request payload in hapi. Because you should never, ever trust provided data submitted by users, a common process is to validate the request payload against a given rule set. hapi streamlines this procedure and integrates a validation process for object schemas with the help of joi.

This guide shows you how to use joi and configure payload validation for incoming requests on a given route.

Before diving into the details, have a look at the series outline and find posts that match your interests and needs.

hapi Series Overview

  1. Get Your Server Up and Running
  2. v17 Upgrade Guide (Your Move to async/await)
  3. Become a Better Developer in 2018
  4. Become a Better Developer in 2017
  1. What You’ll Build
  2. Prepare Your Project: Stack & Structure
  3. Environment Variables and Storing Secrets
  4. Set Up MongoDB and Connect With Mongoose
  5. Sending Emails in Node.js
  6. Load the User’s Profile Picture From Gravatar Using Virtuals in Mongoose
  7. Implement a User Profile Editing Screen
  8. Generate a Username in Mongoose Middleware
  9. Displaying Seasons and Episodes for TV Shows with Mongoose Relationship Population
  10. Implementing Pagination for Movies
  11. Implement a Watchlist
  12. Create a Full Text Search with MongoDB
  1. Create a REST API with JSON Endpoints
  2. Update Mongoose Models for JSON Responses
  3. API Pagination for TV Shows
  4. Customize API Endpoints with Query Parameters
  5. Always Throw and Handle API Validation Errors
  6. Advanced API Validation With Custom Errors
  7. Create an API Documentation with Swagger
  8. Customize Your Swagger API Documentation URL
  9. Describe Endpoint Details in Your Swagger API Documentation
  10. 10 Tips on API Testing With Postman
  11. JWT Authentication in Swagger API Documentation
  12. API Versioning with Request Headers
  1. IP-Based Rate Limits (Part 1 of 7)
  2. Rate Limits for Routes (Part 2 of 7)
  3. Dynamic Rate Limits (Part 3 of 7)
  4. Render a “Rate Limit Exceeded” View (Part 4 of 7)
  5. Show “Rate Limit Exceeded” Error on Login (Part 5 of 7)
  6. Disable Rate Limiting (Part 6 of 7)
  7. Rate Limiter Refactoring & Cleanup (Part 7 of 7)
  1. API Login With Username and Password to Generate a JWT
  2. JWT Authentication and Private API Endpoints
  3. Refresh Tokens With JWT Authentication
  4. Create a JWT Utility
  5. JWT Refresh Token for Multiple Devices
  6. Check Refresh Token in Authentication Strategy
  7. Rate Limit Your Refresh Token API Endpoint
  8. How to Revoke a JWT
  9. Invalidate JWTs With Blacklists
  10. JWT Logout (Part 1/2)
  11. JWT “Immediate” Logout (Part 2/2)
  12. A Better Place to Invalidate Tokens
  13. How to Switch the JWT Signing Algorithm
  14. Roll Your Own Refresh Token Authentication Scheme
  15. JWT Claims 101
  16. Use JWT With Asymmetric Signatures (RS256 & Co.)
  17. Encrypt the JWT Payload (The Simple Way)
  18. Increase JWT Security Beyond the Signature
  19. Unsigned JSON Web Tokens (Unsecured JWS)
  20. JWK and JWKS Overview
  21. Provide a JWKS API Endpoint
  22. Create a JWK from a Shared Secret
  23. JWT Verification via JWKS API Endpoint
  24. What is JOSE in JWT
  25. Encrypt a JWT (the JWE Way)
  26. Authenticate Encrypted JWTs (JWE)
  27. Encrypted and Signed JWT (Nested JWT)
  28. Bringing Back JWT Decoding and Authentication
  29. Bringing Back JWT Claims in the JWT Payload
  1. How to Run Separate Frontend and Backend Servers Within a Single Project
  2. How to Use Server Labels
  3. How to Correctly Stop Your Server and Close Existing Connections
  1. Basic Authentication With Username and Password
  2. Authentication and Remember Me Using Cookies
  3. How to Set a Default Authentication Strategy
  4. Define Multiple Authentication Strategies for a Route
  5. Restrict User Access With Scopes
  6. Show „Insufficient Scope“ View for Routes With Restricted Access
  7. Access Restriction With Dynamic and Advanced Scopes
  8. hapi - How to Fix „unknown authentication strategy“
  9. Authenticate with GitHub And Remember the Login
  10. Authenticate with GitLab And Remember the User
  11. How to Combine Bell With Another Authentication Strategy
  12. Custom OAuth Bell Strategy to Connect With any Server
  13. Redirect to Previous Page After Login
  14. How to Implement a Complete Sign Up Flow With Email and Password
  15. How to Implement a Complete Login Flow
  16. Implement a Password-Reset Flow
  1. Views in hapi 9 (and above)
  2. How to Render and Reply Views
  3. How to Reply and Render Pug Views (Using Pug 2.0)
  4. How to Create a Dynamic Handlebars Layout Template
  5. Create and Use Handlebars Partial Views
  6. Create and Use Custom Handlebars Helpers
  7. Specify a Different Handlebars Layout for a Specific View
  8. How to Create Jade-Like Layout Blocks in Handlebars
  9. Use Vue.js Mustache Tags in Handlebars Templates
  10. How to Use Multiple Handlebars Layouts
  1. Extend Your Server Functionality With Plugins
  2. Create Your Own Custom Plugin
  3. How to Register Plugins for a Selected Server Instance
  4. hapi Plugin for Client Geo Location (by Future Studio 🚀)
  5. Increase Development Speed With Errors in the Browser or as JSON Response
  1. Route Handling and Drive Traffic to Your Server
  2. How to Serve Static Files (Images, JS, CSS, etc.)
  3. How to Use Query Parameters
  4. Optional Path Parameters
  5. Multi-Segment/Wildcard Path Parameters
  6. Ignore Trailing Slashes on Route Paths
  7. How to Fix “Unsupported Media Type”
  1. How to Access and Handle Request Payload
  2. Access Request Headers
  3. How to Manage Cookies and HTTP States Across Requests
  4. Detect and Get the Client IP Address
  5. How to Upload Files
  6. Quick Access to Logged In User in Route Handlers
  7. How to Fix “handler method did not return a value, a promise, or throw an error”
  8. How to Fix “X must return an error, a takeover response, or a continue signal”
  1. How to Reply a JSON Response
  2. How to Set Response Status Code
  3. How to Handle 404 Responses for Missing Routes
  1. Add CSRF Protection on Forms and API Endpoints
  1. Report Errors to Sentry
  2. Don’t Report Errors to Sentry in Development Mode
  3. Logging Fundamentals
  4. Log to Console With Good
  5. Log to File With Good
  1. Getting Started With Testing Using Lab and Code
  2. Run Tests with Assertions using Code
  3. Test Route Handlers by Injecting Requests
  4. Inject Request Payload, Headers and Parameters While Testing Route Handlers
  1. Zero-Downtime Deployments Using PM2

Prepare Your Project and Install Joi

You’ll use the joi module from within hapi’s plugin ecosystem to validate selected fields within the request payload. Before defining the validation itself, you need to add joi as a dependency to your project:

npm i -S joi

Installation process finished successfully? Your project is prepared to make use of joi for input validation.

Use Joi for Payload Validation

Incoming requests pass a pre-defined list of actions like route lookup that matches the request’s path, parse cookies, authenticate the request, parse payload and many more. Once the request payload is parsed and available, the validation procedure gets kicked off. If you didn’t define any validation, hapi skips this step and proceeds with the route handler.

In case you’ve payload validation in place, hapi applies the defined constraints. Depending on whether the given payload data passes the validation process successfully, the request will be proceeded by calling the route handler. If validation fails, hapi will reply with a detailed boom error object including the reason why validation failed.

Let’s get practical and have a look at code that illustrates the application of payload validation for a given hapi route. The route’s handler is located aside the validate configuration within the config object of your route:

var Joi = require('joi')

server.route({  
  method: 'POST',
  path: '/',
  config: {
    handler: …,
    validate: {
      payload: {
        email: Joi.string().email().required(),
        password: Joi.string().min(6).max(200).required()
      }
    }
  }
})

As you can see, the validate object requires you to further specify the validation type, like payload, query parameter and params which describes the path parameters. Within your individual payload object, define the properties that will be checked for incoming requests.

In the example above, you can see that the email and password fields within the request payload will be validated against the given joi rules. email needs to be a valid email string and is a required field. password is a string with a minimum length of 6, maximum length of 200 characters and also a required property. Of course, you can define your validation rules of choice. Within Joi’s API documentation, you’ll find all applicable methods.

In case the validation doesn’t pass successfully, you’ll receive the aforementioned boom error object. The following code block shows the detailed raw response payload that will be sent to the requester.

Raw Response Payload

{
  "statusCode": 400,
  "error": "Bad Request",
  "message": "child \"password\" fails because [\"password\" length must be at least 6 characters long]",
  "validation": {
    "source": "payload",
    "keys": [
      "password"
    ]
  }
}

Actually, you’ll receive a proper 400 Bad Request HTTP response and the content from the code snippet above is contained within the response body.

The message property indicates the error details and what to adjust within future requests to avoid the issue. Within the validation field, you can find the keys that caused the error. Also, the error object contains the statusCode and HTTP error as individual fields.

Outlook

We hope you enjoyed this guide on payload validation and take away the insights on how to improve your code by validating fields as early as possible. Validating incoming user data as early will keep your code base clean and small. You don’t need to perform the validation steps yourself within the route handler.

Benefit from hapi’s functionality and put in some brainpower to get going with joi and what rules are applicable for the request payload, query and path parameters.

The request payload isn’t the only option to pass data from clients to server. Validate query parameters as well.

We appreciate feedback and love to help you if there’s a question on your mind. Let us know in the comments or on twitter @futurestud_io.

Make it rock & enjoy coding!

Additional Resources

Marcus Pöhls

Marcus is a fullstack JS developer. He’s passionate about the hapi framework for Node.js and loves to build web apps and APIs. Creator of Futureflix and the “learn hapi” learning path.

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