A Practical Guide for Migrating to Server Components

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Server Components are the hot new thing, but so far much of the discourse around them has been abstract. Let's change that. This talk will focus on the practical side of things, providing a roadmap to navigate the migration journey. Starting from an app using the older Next.js pages router and React Query, we’ll break this journey down into a set of actionable, incremental steps, stopping only when we have something shippable that’s clearly superior to what we began with. We’ll also discuss next steps and strategies for gradually embracing more aspects of this transformative paradigm.

Fredrik Höglund
Fredrik Höglund
28 min
20 Oct, 2023

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Video Summary and Transcription

React query version five is live and we'll be discussing the migration process to server components using Next.js and React Query. The process involves planning, preparing, and setting up server components, migrating pages, adding layouts, and moving components to the server. We'll also explore the benefits of server components such as reducing JavaScript shipping, enabling powerful caching, and leveraging the features of the app router. Additionally, we'll cover topics like handling authentication, rendering in server components, and the impact on server load and costs.

Available in Español

1. Introduction to Server Components

Short description:

I'm a freelance consultant and a React query contributor. React query or TAN stack query version five is live since Tuesday. We'll be talking about planning and preparing, setting up for server components, migrating a single page, adding layouts, and moving stuff to the server. Our goal is to approach the use of server components as an incremental migration and bring the whole team along. We'll use Next and React Query to demonstrate the process.

This is what I'm talking about. I'm a freelance consultant and a React query contributor, as he mentioned, and you can find me on Twitter. We actually changed that from X after I saw the polls, but I do say Twitter too. I'm FMJ.

So usually announcement comes at the end of a talk, but since TK Dodo announced this earlier this week, React query or TAN stack query version five is live since Tuesday. So we'll try that out. So we won't be using any of these new APIs in this talk, but we will be using some of the new syntax.

Okay. This is what we'll be talking about today. Planning and preparing, setting up for server components, migrating a single page, adding layouts, and also we'll talk a little bit about moving stuff to the server, but not that much. We only have 20 minutes. This is going to be a whirlwind talk. I won't be able to cover everything, but I hope to give you a roadmap to get you started and some helpful tips along the way.

First, let's talk about some goals. If you have an existing app today and you want to use server components, you are going to want to approach this a bit differently than if you have a Greenfield app. We want this first and foremost to be an incremental migration, because big bang migrations never ever work. This is also a huge new paradigm to learn, so we want to learn this step by step, and we also want to bring the whole team along as we do so. Maybe people here at React Advanced have already read all the docs, seen all the talks, but your team might not have. So you have to gently lead them up these stairs, not just run up there. And to do this, we are going to keep as much as possible of the existing mental model of your application and your existing code. Or put a bit differently, don't try to do everything at once. And this kind of summarizes my talk, I guess. First we want to get this to work, then we can adopt all these new features that we're itching to adopt, right? And, again, if you're starting at Greenfield Lab, you might want to embrace the future right away.

In this talk, we are going to use Next and React Query. It is kind of a React Query talk in disguise, because I'll show you how to use server components with React Query, but that's not the main point of it. It will focus a bit on data fetching, though, and the reason for that is this. A lot of examples and migration guides that exist today have something like this. You're doing a fetch in a server component. You're adding some configuration. And that's it.

2. Planning and Preparing for Migration

Short description:

If you're building a complex web app today, you also have to deal with mutations and invalidations of data. The approach we're going to take is to use server components mainly as data loaders and not render that much in them. We're also going to keep using React Query and your existing caching logic. To prepare for this migration, read all the documentation, inventory your utils and third-party libraries, and think about deployment, DevOps, tests, and authentication. Plot out which pages you think you're going to need to migrate together and pick a basic first route to migrate. Then wrap those in strict mode.

If you're building a complex web app today, you also have to deal with mutations and invalidations of data, and right now, before server components, there's only one way to do that, right, and that's on the client. So I want to talk a bit about how you do this if you're using a third-party library to manage your data fetching today. That doesn't have to be React Query, of course.

Another thing is that the Next docs currently list four ways to fetch data in server components or when using server components. And I want to claim there's a fifth way, which is the way a lot of us might be doing it today, which is prefetching data on the server, but doing all the invalidations and refetching and things on the client. Possibly with third-party libraries.

The approach we're going to take is to use server components mainly as data loaders and not render that much in them. Keep the rest of the application as client components, and we're gonna keep using React Query. We're also going to keep using your existing caching logic in your application. Because you already have working caching, and caching is hard to get right, right? And the app router has four. Four caches that interact with each other. And these are super powerful. They are great, and you want to opt in to them later after your migration is done.

So, to do that, we'll try to mimic the existing behavior that you probably have with get server side props or get static props, and the way we'll do that is by exporting this configuration, force dynamic or force error, and we'll get into that. But first we need to plan and prepare for this migration. And the very first thing you want to do is read all the documentation. Grab a coffee or a tea or something, spend an afternoon with these documents, the React documents, especially the next migration guide and the rest of the next documents, they are really, really good, very comprehensive, and any third party library documentation too.

Then you want to inventory your utils and your shared code, think about if there's anything you need to do there to support the app router. You want to inventory your third party libraries. Do they actually support the app router? What are you going to do if they don't? You want to think about deployment, DevOps, tests, authentication, but you don't have to solve all of these things now, but it's very good to get a feel for the scope and anticipate any hurdles you might have for your application. Where is this going to get tricky for you? So the pages and the app router are in a sense two separate frameworks. They have their own bundles and navigating between them is a full page reload. So that is probably fine for a lot of your pages, but for some pages it might not be. If you have a category page and a product details page that you navigate between very often or something like that. So plot out which pages you think you're going to need to migrate together. Then you want to pick a basic first route to migrate. This is probably your company about page, right? If I care to guess. And then you pick a more complex second route to migrate. And the first thing you want to do is to wrap those in strict mode.

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