Learn how to handle error messages and status codes effectively in your web development projects, making TypeScript happy and improving your experience.

Learn to handle nulls and throw custom errors in Remix with "invariant response" for status codes and error messages.






Handling Error Responses with Remix

[00:00] We've got a couple of places that are missing data. We threw up this TS expect error that Lily the life jacket is super not into, so we're going to remove those here really quick so that we can reveal that. Basically, the problem is, this query to our database could potentially give us a null for the user, because maybe the user doesn't exist.

[00:18] What we're going to do is add an if statement to say if there's not a user, then we're going to throw a new error. That makes TypeScript happy. But it doesn't exactly make me happy. If I were to go to whatever right here, we're going to get this error that doesn't look good at all.

[00:38] Again, we're going to be actually making it look nice later, but the error message itself is not very helpful. The network request gives us a status of 500. Search engines and browsers and things operate differently based on the status code that you return. It actually is very important to give a proper status code,

[00:57] even though we're not going to be able to give them a really helpful resolution to this sort of thing. We'll basically just say, yeah, sorry, this doesn't exist. But for now, let's just give them a nice status code. Let's say new response, and we can at least give it a nicer error,

[01:16] something like user not found, and then a status of 404. Just with that change now, we're getting our status of 404. If you look at the headers right here, we're going to get the status code 404 not found,

[01:34] and then the browser can behave appropriately for this particular situation. As cool as it is that we can throw these responses, and Remix will handle those and take those response status codes and everything. Eventually, we can even pass data to

[01:53] display some more useful error message. As cool as this is, it would actually be even cooler if we had a nicer abstraction for this. If we could just move this out and make a function that says assert thing, and here's the thing, and it's any type.

[02:12] Then we move this into here and we say thing. Then maybe we could provide an error message or something like that. But here we can just say assert thing user, and then move on with our day. If you were to make this assert thing into a proper assertion function, then TypeScript would know about what we're doing here as well.

[02:32] In fact, that is precisely what we have done. As the extra credit shows here, you can switch this for invariant response from our app utils miscellaneous. Now TypeScript knows, okay, so it is impossible for the code to

[02:50] proceed here if the user is not defined. Let's also add an error message, user not found, and then our status code, status of 404, and now we're getting the same behavior. But in a really nice simple API, we just literally stick that line of code right there,

[03:08] and we're handling this error case really nicely. If you want to dive into that invariant response, it's actually not a really complicated function. It has this asserts condition. That's what you're passing in at the first. You have the message, you can offer that as a function, a callback function if you desire,

[03:26] and then a response in it that gets added to this response. That's the idea, you're throwing responses. We can do the same thing over here. Now that we know about that abstraction, we'll just use that straight from the start. We'll say, get rid of that, and then invariant response,

[03:45] note, and note not found, status 404. There we go, awesome. So then if we come over here, and we say, let's go to this note, we're going to get a nice 404. Still not a great error message page, but it is giving us the right status code, and we'll make the errors better later.

[04:03] And we'll do the same thing for our owner. So let's get rid of this TS expect error right there, because we no longer expect there to be an error. We'll say invariant response, owner, and we can say user not found or owner not found. And now if I come here and say whoever,

[04:22] now I'm going to get my 404. So that's one of the cool things about Remix is just the ability to throw an error response, or throw a response object, and then Remix will handle that appropriately. And yeah, now we can get rid of this as well.

[04:40] We're no longer expecting an error, huzzah. So there you go, that is invariant response. I definitely recommend having a function like this in your application, because it just makes doing this sort of thing a lot easier. But the core idea is that we're throwing responses,

[04:58] and we can pass some sort of content body, and the status, and whatever else you want as part of that response, which I think is pretty rad. You could do a redirect as well, which would be pretty cool. And what's nice about doing the throw, rather than a return, because people ask me about that sometimes. If we did a return, you'd have to say,

[05:18] okay, here's the maybe response. And then you'd say, if there's a maybe response, then return the maybe response, right? So that wouldn't be nearly as cool as literally just this. So that's why I really actually like the throwing response mechanism that Remix gives us.

Handling Error Messages

[00:00] So, this works fine until you decide you want to try something funny and then you get a big kablooey with an error message that really isn't all that useful. We'll take care of handling error messages and making them look nice in a future part of this workshop, a

[00:18] future exercise, but we do want to make things work a little bit nicer for us during our development time, and that means making TypeScript happy. Again, I repeat over and over again, TypeScript isn't making your life terrible, it's just showing you how terrible your life

[00:34] is and just letting you know, hey, you've got to think about these cases. So, like I said, we'll make this error page look a lot nicer in a future exercise, but for right now I just want you to handle situations where the user data does not exist. Additionally,

[00:51] right here we're getting an application error, so we're getting a 500. We want to get a 404 for this type of a thing, so we're going to be handling those status codes properly in this exercise and also making it a nicer developer experience for us, and then in a future exercise we'll actually make this look pretty. So, go ahead and let's take care of the status

[01:11] code and handling those errors, making TypeScript happy, and then I'll see you when you're done.

Developers working on modern web applications today face a myriad of challenges.

The apps we build are expected to be good looking, fast, and secure. They need to be interactive, responsive, and accessible. They need to be SEO-friendly, and they need to be resilient to errors.

In order to be successful, you need to ensure you have a solid foundation to build on.

Full Stack Foundations is a comprehensive, in-depth workshop that sets the stage for the rest of the Epic Web series. It's designed to equip you with the current best practices for handling CSS, routing, data loading, and more.

This isn't some basic "intro" workshop! Even if you're an experienced developer, you'll learn new skills and techniques that will help you build better apps.

<Testimonial author={{name: "Gwen Shapira"}}>

It was 🤯. A lot of fun, and I learned so much in one day. Even with 23 years as a software engineer, I have a much clearer understanding of how the web actually works. Now, months after this workshop, I’m working on a web project and this gave me the mental framework I needed to quickly ramp up and feel competent. I’m not even using the same tools Kent uses in the workshops! 13/10.

</Testimonial>

## Styling

In recent years, CSS has seen a lot of evolution in its usage and tooling. There are new best practices for importing stylesheets, managing assets, and optimizing styles. Failing to follow them can lead to slow-loading pages and a maintenance nightmare.

Here, you'll learn how to handle styling right:

- Loading external stylesheets & other resources
- Managing assets with fingerprinting and caching
- Compilation with PostCSS and Tailwind CSS
- Bundling CSS for libraries and components

## Routing

The URL is critical for the web, and is closely tied to your application's routing. Making suboptimal decisions affects loading performance, navigation, and overall experience.

This section is a deep dive into routing, from the basic filesystem structure through nested routes and dynamic parameters:

- Conventions for signifying routes
- Layout and URL nesting
- Navigation and linking
- Dynamic route params
- Resource routes

## Data Loading

The web is all about data, and nothing frustrates users more than when loading is slow or broken. This section introduces you to AJAX/fetch and Remix loading features, giving you the tools to build stable, fast-loading applications:

- Working with `Request` and `Response` objects
- Fetching data for initial and subsequent loads
- Accessing environment variables
- Connecting routes to loaders

## Mutations

Interactivity makes apps engaging, but also introduces complexity. You need to ensure that the thing that happens when a form is submitted is what the user expects. Here you will use form methods and actions to mutate existing data in a mock database:

- Creating forms with `method` and `action`
- Storing and extracting form data
- Handling invalid submissions
- Form state management
- Specifying intent

*This module sets the stage for the complete Professional Web Forms workshop.*

## Scripting

The browser is capable of quite a lot on its own. Up until this point of the workshop, the Epic Notes application will work without any JavaScript. However, scripting allows us to enhance the user experience in ways that would otherwise be impossible.

In this section, you'll incrementally add in features like client-side pending UI, prefetching, and optimistic updates:

- Scroll position restoration
- Considerations when overriding default browser functionality
- Server and client bundles & entry files
- Preloading data & code for anticipated actions
- Transitions with the `useNavigation` hook

## Search Engine Optimization

Ignoring SEO is like building a store without a sign— people simply won't find you. If you want to be successful, your site needs to be discoverable and optimized for presentation on those platforms.

SEO is a very broad topic, but this section will get you set up on the technical side of the equation:

- Essential tags and attributes
- Overriding default metadata for specific pages
- Dynamically set metadata for social sharing
- Reusing parent data for nested routes

## Error Handling

Even the best apps can break, but what separates the good from the great is how they recover. Lack of proper error handling can lead to frustrated users and lost business.

This section will teach you how to anticipate, handle, and recover from errors, making your application resilient and user-friendly.

- HTTP status codes
- Using `ErrorBoundary` components to contain errors
- Handle thrown errors when fetching data
- Error bubbling from child routes to parent routes
- Implement useful 404 pages

The Full Stack Foundations workshop covers modern web development best practices including Styling, Routing, Data Loading, Forms, SEO, Error Handling, and more!

Full Stack Foundations

Kent C. Dodds

Full Stack Vol 1

Intro to Full Stack Foundations Workshop

Introduction

Intro to Styling 

Learn how to add favicons and other link elements to your Remix application, ensuring proper rendering across nested routes.

Remix includes a Links component that enables us to add links to the head of our application.

Using Remix's Links Component

Manage Asset Links in a Remix Application

Learn how to handle caching and automatically update static assets, like favicons, without waiting for the cache to expire.

By importing the favicon as a module, we can leverage caching and immutable URLs to ensure that it is always up-to-date.

Caching the Favicon

Asset Import Caching Issue

Learn how to link a CSS file globally in your application to apply styles across all pages, including specific font configurations.

Using the links function, we can add global styles to our Remix app.

Adding Global Styles to a Remix App

Add Custom Fonts to the Global CSS

Remix has built-in support for PostCSS and Remix, but there needs to be a little bit of configuration.

When PostCSS and Tailwind CSS are properly configured, Remix will properly compile the CSS and apply it to your application.

PostCSS and Tailwind CSS Configuration

Using PostCSS and Tailwind CSS in Remix

Remix allows you to bundle CSS files together to reduce the number of link tags on the page.

Create a bundled CSS link with help from the cssBundleHref function from Remix's css-bundle package.

Configure CSS Bundling

Bundling CSS in Remix

To mark the end of this section, take a quick break for a Dad Joke.

Dad Joke Break

Styling

An overview of routing in web development and how it works in Remix.

Intro to Routing

The Flat Routes convention provides a simple way to create nested routes in a Remix app.

Learn how to configure routes and create nested pages in Remix, a versatile framework for building web applications.

Creating User Profile and Notes Pages with Remix Routes

Routing in Remix

Learn how to create links in your web application to enable seamless navigation between different pages, including home, profile, notes, and specific note IDs.

Remix offers Link and NavLink components to create absolute or relative links with configurable behavior.

Adding Absolute and Relative Links

Adding Navigation Links

By adding dynamic parameter support to our routes, we won't have to have everything hardcoded.

Remix's useParams hook allows you to access route parameters in your components.

Access Params with useParams

Adding Dynamic Parameter Support

A loader route is useful for handling network requests for fetch requests or document requests.

Anything you can do with HTTP, you can do with resource routes. In this example, we use one to serve CSS.

Example Resource Route Usage

Adding a Resource Route

Take a quick break from the Routing section.

Routing

Intro to Loading

Learn how to use a mock database implementation to load and display user notes in your web application. 

Discover how to fetch and filter data from databases, minimize data sent over the network, and ensure type safety, resulting in improved performance.

Efficient Data Loading in a Remix App

Loading Data to Your Database 

Dad Joke Break Loading

Loading

Intro to Mutations

Learn how to create a form to edit data, following a provided design, and prepare it for future functionality. 

Explore the importance of the post method, encoding form values, setting default values, and utilizing common browser behaviors like reset and submit buttons.

Creating Form Components with Remix 

Building Forms 

Discover the importance of setting the method to GET or POST, and the potential issues that arise from using unsupported HTTP methods.

Learn how to handle form submissions in Remix, update the database, and automatically revalidate and update data on the page without a full page refresh. 

Handling Form Submissions and Mutations

Handling POST Requests for Form Submission

Learn how to handle error cases in form submissions and anticipate potential mistakes made by users. 

Leverage the formdata.get function, we can ensure that only valid string values are accepted, avoiding potential errors and providing a better user experience.

Form Data Types and Validation 

Handling Form Errors and User Mistakes 

Learn how to enhance a button's functionality by wrapping it in a form and handling the deletion of data through a network request. 

Learn how to handle various scenarios and considerations when performing form submissions and mutations using web platform primitives. 

Form Submissions and Mutations 

Button Forms Data

Improve form submissions for multiple actions with additional data, enabling efficient handling within a single action function.






Discover how to use the name and value attributes in buttons to differentiate between different types of form submissions. 

Leveraging Name and Value in Buttons for Multiple Form Submissions

Handling Multiple Actions in a Single Action Function

Dad Joke Break Mutations

Mutations

Intro to Scripting

Remix operates effectively without JavaScript for basic functionality, but JavaScript becomes essential for advanced features and an optimal user experience.

Optimize Your Web App: Add Client-Side JavaScript, Implement Code Splitting, and Enhance Connectivity.  

Improving User Experience with Client-Side JavaScript

JavaScript in Remix: From Optional to Essential

Mastering Scroll Behavior in Remix with JavaScript: When to Auto-Scroll and When to Enhance User Experience.

Learn how to implement scroll restoration in your web app using the scroll restoration component from Remix Run React. 

Enhancing Scroll Restoration 

Page Navigation with Scroll Behavior

Dive into the implementation details and constraints of the Remix framework, and discover how to use environment variables to import DevTools dynamically.

Learn how to securely expose environment variables in a web application, allowing access to vital information on both the client and server side.

Exposing Environment Variables in a Web Application

Environment Variables for Client-Side and Server-Side 

Learn how to leverage JavaScript prefetching to anticipate user actions and preload required resources, improving page load times and user experience.

Understand how prefetching works, observe the automatic caching of resources, and discover the potential of future intelligent intent detection.

Enhancing User Experience with Prefetching

Optimizing Resource Loading with JavaScript Prefetching

Learn how to provide visual feedback to users during slow or bad network connections by implementing a pending status with a spinner using status buttons.

Learn how to add a pending state to form submissions in your Remix application, providing users with visual feedback and preventing multiple submissions. 

Adding Pending State to Form Submissions with Remix

Improve the UX with Pending UI

Dad Joke Break Scripting

Scripting

Intro to Search Engine Optimization (SEO)

Enhance web appearance with meta tags: set title and route-specific meta tags in your page's head.

Boost SEO and UX with title, description, charset, and viewport meta tags in your HTML.

Meta Tags for Better SEO and UX

Configuring Meta Tags 

Optimize user experience and SEO by making sure each page has relevant and distinct metadata.

Master dynamic meta tags in RemixRunReact for custom SEO on specific routes with parent route fallbacks.  

Managing Meta Tags and Descriptions in RemixRunReact

Dynamic Metadata for Different Routes

Customize meta information based on user profiles, note titles, contents, and more. Expand your knowledge in the next section with additional challenges.

Ensure type-safe, flexible dynamic data handling in Remix's meta function with TypeScript, plus explore fallbacks and error strategies for UX

Handling Dynamic Data with Remix's Meta Function

Customizing Meta Tags with Dynamic Data

Learn how to access parent route data in order to enhance the notes index and note ID pages. 

How to leverage TypeScript's type checking to generate metadata for routes dynamically, ensuring type safety and flexibility in your app.

Implementing Dynamic Meta Data for Routes in a TypeScript Application

Optimizing Metadata for User Info 

Dad Joke Break - SEO

Search Engine Optimization

Intro to Error Handling

Refine error handling and beautify error pages with Remix's utilities for user-friendly experiences. 

Learn how Remix enhances error handling in server-rendered React applications.

Error Handling and Error Boundaries

Improving Error Handling and UI on User Profile Page

Use React error boundaries for user-friendly handling of expected errors, like 'user not found,' with customized messages and status codes. 

Improve UX with customized user not found error messages based on usernames, while managing diverse error responses effectively. 

Improving Error Messages for User 

Handling Expected Errors with Error Boundaries

Implement reusable error boundary with status handlers, custom messages for common errors (403, 404, etc.) across routes, boosting error handling. 

Handle nested route errors (e.g., resource not found, invalid IDs) with local error boundaries, preventing app-wide issues.

Error Boundaries and Handling in Nested Routes

Streamlining Error Handling in Routes with a General Error Boundary

Efficiently handle route and component errors with a dedicated fallback document component for meta, links, scripts, improving error handling. 

Enhance error handling and UX by refactoring app components: isolate app logic, implement error boundaries, and preserve loader data. 

Refactoring App Components for Better Error Handling

Improving Error Handling with a Document Component

Handle 404 errors in React Router with a splat route for proper header/footer rendering and optimal error handling practices.

Craft dynamic 404 pages via Remix splat routes. Leverage error boundaries for efficient not-found route handling. Explore setup and advantages.

Full Stack Foundations

Full Stack Foundations

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Handling Error Messages

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