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  3. hapi — Optional Path Parameters

hapi — Optional Path Parameters

Within the tutorial on driving traffic to your website by adding routes to your hapi server, we’ve already touched the basics of path parameters. Within this guide, you’ll get additional information on path parameters, specifically optional ones.

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. 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. Query Parameter Validation With Joi
  2. Path Parameter Validation With Joi
  3. Request Payload Validation With Joi
  4. Validate Query and Path Parameters, Payload and Headers All at Once on Your Routes
  5. Validate Request Headers With Joi
  6. Reply Custom View for Failed Validations
  7. Handle Failed Validations and Show Errors Details at Inputs
  8. How to Fix AssertionError, Cannot validate HEAD or GET requests
  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

Optional Parameters on Routes

Hapi allows you to define optional path parameters that aren’t required to match a given route’s path. Let’s illustrate this topic using the Future Studio blog as an example. You can view a list of recently published tutorials with a shortened content preview when visiting /blog. For the full tutorial’s content, you need to visit /blog/{tutorial-title-as-slug} where {tutorial-title-as-slug} is the individual title’s slug.

For any route definition that follows below, we’ll use the following base URL:

https://futurestud.io

You already know that there are at least three required parts for a route definition in your hapi server: method, path, and handler. Your interest is especially geared towards the path where we define an optional path parameter. We’ll use the blog example from above to illustrate how the optional path parameters are defined within the path field:

hapi v17

server.route({  
  method: 'GET',
  path: '/blog/{slug?}',
  handler: (request, h) => {
    const params = request.params || {}

    if (params.slug) {
      // render tutorial content
      return h.view('blog/tutorial-details')
    }

    // render blog overview
    return h.view('blog/overview')
  }
})

hapi v16

server.route({  
  method: 'GET',
  path: '/blog/{slug?}',
  handler: function (request, reply) {
    var params = request.params || {}

    if (params.slug) {
      // render tutorial content
      reply.view('blog/tutorial-details')
    } else {
      // render blog overview
      reply.view('blog/overview')
    }
  }
})

You need to provide a parameter name followed by a question mark encapsulated in cURLy brackets: /{slug?}. Essentially, the question mark tells hapi to match this route for any requests to /blog and /blog/<whatever-comes-here>. The path parameters are parsed by hapi and provided to you as a field on the request object. You can access the object containing path parameters by using request.params.

The path parameter object could look like this:

{
  slug: 'test'
}

Please notice, that the route definition above doesn’t match a request with a URL that has three path segments, like /blog/{slug?}/comments/.

Only Last Named Path Parameter Can Be Optional

You can’t define a route having an optional parameter in the middle of your path. Actually, this restriction is kind of obvious when creating an exemplary route’s path like /blog/{tutorial-title-as-slug?}/comments/{commentId}. Creating a request without providing a {tutorial-title-as-slug}, the URL will look like /blog//comments/123 and that’s an invalid request URL.

Notice: only the last named path parameter can be optional.

Outlook

This guide walked you through the definition of optional path parameters for your routes and also showed you how to access them within your handler functions. When making use of optional path segments, please keep in mind that only the last named parameter can be optional.

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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