Get rid of your API schemas with tRPC

I'm so happy to be here. And today we are talking about how to get rid of your API schema with trPC. So I want to start my talk with schema fatigues. So we have two main way to communicate from your server and client. We have open API, and we have GraphQL. So open API is open API specification, the final language agnostic interface. So you know HTTP verbs like POST, GET, PATCH, DELETE, et cetera, et cetera. And it's a new language to know.

So if you want to use open API, you have to learn a new specification. Then you need to write case-sensitive JSON or YAML. By the way, YAML sucks. And you have to generate your schema, your type script types, every time you change something into the open API documentation.

Let's see the GraphQL part. With GraphQL, it's an open-source data query, manipulation language, again language, and you need to learn new things. So it's a GraphQL format. And you need to learn the new specification, so query, mutations, stuff like that, so on and so forth. And then you have always to generate your type script types. So if you change something in the GraphQL, you need to generate this type and you dump it into the client.

I'm struggling a lot with this kind of things because I'm working in a consultancy company, Flowing, and I found a solution in TRPC, and then I will show you how.

My handle in LinkedIn and Twitter is Giorgio underscore boa. If you want to tweet about this talk and tag me and tag also the conference, I really appreciate.

So let's jump back to TRPC. TRPC is a quite famous library. More than 100,000 weekly npm downloads and more than 60,000 stars on GitHub. So quite popular. Okay. All the library is based on this type of that you can see on the screen. Okay.

All the library is based on this type of that you can see on the screen. Okay. So here we have an object. My job object with my first name and last name. And with the type of, we are able to extract the shape of this object to get a type. Okay. And now we will show how it works with TRPC.

Here I have a next JS application, a simple one, and I decided to add from scratch TRPC to show you how easy it is to implement it. So I created also a connection with Prisma because TRPC and Prisma are really a big match. Okay. So here we have our schema, Prisma schema is our model, model author, okay, and we have a seed because Prisma can help us with the seed in our database if it is empty. Okay, we have a source folder, and as you may say, know, in pages we have the slash API folder. Inside of API folder we have we need to create a tRPC folder, and inside of a tRPC folder we need to define a file like this one with square brackets, and next for us grab all the query parameters and give us the information. So we need to expose this endpoint. In this endpoint we define from tRPC next with this API, we define our endpoint. In this endpoint we have a few configurations, but the most important thing is this up-router. In this up-router we have the possibility to define many routers. Here we have only the author router and here we have the typeof I mentioned before. So, from this object we are extracting the shape of the object and defining the up-router. This type is really important for the client. And now we will see how. This is my author router and in this author router, I have a few different procedures. So, I define to get a list of authors, I can add authors and then I can delete one, of course. So, this is my business logic and in the business logic, I put the Prisma API. So, Prisma author dot find many or, for example, if I want to add a new author, Prisma author find first and then if it's not present, I will create the record.

Okay, but let's jump to the client. We see before that we are export type up router. So, we are extracting the shape of this router and now in the client folder, we define the TRPC file, and in this file, there is a few configuration, but the most important part is this one create TRPC next with the generic and here we define up router. The up router arrive directly from the folder we saw before. So, server routers underscore app.

In this way, we are able to use TRPC in the client part. So, here is our slash index, okay, the own page of our application. We can use TRPC like this, TRPC dot author dot list, but if I remove this list and I press control space, as you can see with TypeScript, we are able to know that I can call the add, delete, and list. And this is so cool because we didn't generate any kind of types to do that, is all of things out of the box.

Okay, so I, okay, great, so as you can see here, we are looking for the authors. Then we manage the handle delete and handle save, and every time I save and delete, I invalidate the list to refresh the list. So we can start our application. Here there are some Prisma codes. Okay. And if we go here, we have this list, and with the save button we save a new author, and then we can delete them. Great. One really cool thing is that if you go into the routers, in the author router, great, and we decide to change the name of the procedure, so let's change this one, we can rename the Add to new, and boom, into the index here, you can see that TypeScript renamed it for me, so it's really great things. But if we decide to, don't do with the renamed symbol, but do it manually, so I remove here head, okay, if we do it manually, like this one, as soon as I move myself into the index, we can see that TypeScript is notify me that something changed under the hood. So it's a really great benefit to interact from your server and client part, and I think this is so cool.

But I want to show you more. Now we are going deep into the library, because I want to show you how it works under the hood. So let me refactor my class. Here, add new, remove, save. So I think now it's okay. So if I go here. Yeah, perfect. If I open the inspect, I place the few breakpoints into the client library of TRPC. Okay, so if I click on this one, great. And I refresh. As you can see here, we are defining, we are into the TRPC client. Maybe you can't see. Maybe yes. Okay, we are inside of the TRPC client, and we are defining the methods. So, query is a get, mutation is a post, of course, because a mutation needs to have some information extra. Okay, if we go on, we did debugger, and we enable this to debug.

Okay, refresh. Maybe I can, okay. Okay, zoom a little bit. Okay, as you can see, we have use query. This is our internal function, and inside of use query, we have the path, so author.list. If we go on with debugger, we have the mutation, so we have author.add, and also author.delete. Great.

And I want to show you another things from the client. If we go on, here we have the HTTP request, so under the hood, the library is going to trigger an HTTP request, and look at the URL. So as you can see, slash API slash TRCP slash blah blah blah. So author.list is our procedure, and then you have a lot of parameters that Next.js under the hood, grab for us, and then we, the client part of TRCP is able to call our business logic. But how? Let's see in action the client part, the server part.

So if I put a debugger here, and I run, maybe I stop this one, and I run the debugger from the Visual Studio Code, the application, of course, is the same, because it's the same code base. Okay. As you can see here, we have a breakpoint into our business logic part. But if we jump back a little bit, we can go into the library. So here you can see TRCP server, this index dot blah, blah, blah. Okay? So if I refresh the application, I want to show you this particular property. So let's check. Okay. Great. So inside of the OPTS, we have procedures. Inside of these procedures, we have list, add and delete. And this is the internal function of TRPC server. And inside of delete, we have underscore def. And inside of underscore def, we have the resolver. Resolver is a function. We have Webpack stuff. But in the end, the function is our function. So Prisma dot author dot find many.

Select them. Blah, blah, blah. So if I run the application, as you can see, all the flow ends here. So this is how more or less the TRPC server works.

Great. So let's jump back to the slides. To discuss about the pros and the cons of the library.

So pros. No code generation, as you see before. We didn't generate any kind of code about our procedures, mutation and stuff like that. Type safe by default. So we changed the name of the procedure, and TypeScript soon alert us that something is wrong. And then better collaboration between front end and back end. Because we have a big language, because in the back end, we call the add, and in front end the same. With REST API, sometimes the name of the function are different. So now, with this library, collaboration, I think is better.

What are the cons? Typescript stack. So you need to have back end in TypeScript, and front end in TypeScript as well. If you want to have a versioning of your API, or select some particular fields in a model, you want to select only one field, stuff like that, you need to create more procedures. One for version 1, one for version 2, and so on and so forth. And another cons, that is not really a cons. If you need to expose this API to the public, you need to use this particular library. This library is on top of TRPC and it's TRPC-openAPI. So with a decorator, you are able to expose this API in a public and create also the open API documentation.

Great. So, a summary. If you want to start right now with the TRPC, you can use create.t3.gg. This library bootstrap TRPC application with Tailwind, Prisma, NextAuthentication, and etc, etc. A lot of things to do without manual configuration and it's really cool. Who is using TRPC? Netflix, InterValcal.com, but in this particular issue, you can find a lot of company that signed the name to show that they are using TRPC and if you want to try it now, you can go in trpc.io and you found a lot of resources about TRPC.

So here I insert a slide to take a picture of you because I need to prove to my wife that I was at the conference. Can you say hi? Hi. Great, great. Thanks. Thank you very much Giorgio. Please come into our Q&A booth.

That was a great talk. I have been a little bit lazy myself learning about TRPC and I'm glad I didn't because now I learned it from you. So that was time well spent. That's awesome. And I think a lot of other people have also learned a lot because we have a lot of good questions here.

And of course we have to start with the first question. It is the Elon question. Okay. Would Elon Musk approve of more than 200 TRPC calls and how do you make sure that they aren't poorly batched? Okay. I think Elon Musk is too pitchy. Let me say. Okay, it depends on your context. You have to reason on the TRPC stack. And if you have a lot of procedures, you need to divide them into many services and then communicate with the services, with the TRPC or maybe other channels. Yeah. Okay. So basically he does not know what he's talking about. Yeah. Yeah. Never, never. Ellie is clapping over there. Yeah, very sad clap. Okay. Let's keep going.

This is a question I actually also was thinking about. Like how would you handle a situation where you have multiple front ends that aren't in a mono-repo with a back-end, right? Is that something TRPC can support or is it only for that sort of like back-end for front-end architecture?

Okay. So you have a mono-repo with a ... You don't have a mono-repo. Don't have a mono-repo. So you have a client in one repo and you have a server in another repo. How do these two things keep in sync and how do they communicate? Okay. This is a really great question. Unfortunately, I have the answer. So you can ... If you have multiple repo, you lose the refactoring feature, of course, because you have the code base in two different parts. But if you encapsulate the type of the router inside our library, you are able to include that library in the client. But in the end, you will struggle with versioning things and stuff like that. So you can do it. Would you recommend it? I think the full stack TypeScript is the best approach. But if you want to include tRPC in your application with multiple repo, you can do it.

Next question is a question of scale, as always. Can tRPC work for large-scale applications, especially monoliths? Or is it best suited for smaller apps and microservices? I think it's best with microservices and create multiple services. There are some POC from the author of tRPC that is showing how to integrate multiple services to communicate and create microservices architecture. That's cool.

There's a question. What are the advantages of tRPC over Relay, specifically, Facebook's relay framework? Have you used that and do you know what the advantages might be? No. Yeah, that's a tricky question, I think. Relay is one of those things where the people who love it truly love it and everybody else doesn't understand it. So talk amongst yourselves, find yourself a Relay buddy and convince each other to use it. I don't think I have answered this question either.

It's a Elon Musk question. How do you deal with caching and cache invalidation of entities in tRPC? Is it built in or do you have to do it yourself? Hander De Hoody is using a React query so you can grab all the features of a React query. Also a cool feature about tRPC is the batching. So if in one second you fire a lot of calls, Hander De Hoody is batching them to create cool stuff.

Nice. Let me just see, there's a couple more questions, maybe let me just get them through the moderation and then we'll read them together. Here we go.

Does tRPC handle race conditions when multiple people hit the API to perform the same action? Or are things like that offloaded to Prisma? So basically I think the question is about conflict resolution. The conflict resolution is inside of your business logic. As I showed before, if I want to create another author with the same last name, last name for in this case is the key, the primary key, you need to check before if the primary key exists or not. And then, if it exists, throw an exception. All right.

This is an interesting question. So tRPC for clients only? Does tRPC have any use if you don't actually have a server component? There's not much you can do with it, right? I think no. No. So, the tRPC client doesn't make sense without the tRPC server. Because it's calling the trcp, trpc endpoint, and no. Yeah. By the way, tRPC, it's a hell of a mouthful to say. So RPC is a remote procedure calls. But what's T for? Is it TypeScript or types? TypeScript, I think it's TypeScript RPC. Because RPC is calling a function of another server. I misspell trcp, trcp a lot. It's a mess. Yes.

All right. Well, let's get into our hot topic, hot potato issue. Do you think GraphQL or REST is better than tRPC in some cases? Are there cases where tRPC is not going to be the right solution and GraphQL or REST would be a better approach? Yeah, I'm smiling. Because I know the answer. Okay? In some context, tRPC is so good. But if you need to expose with a public API, maybe REST API is better, GraphQL as well. If you have multiple clients, like let me say TV, mobile, and frontend application, and you need to grab some property from a model, maybe GraphQL fits better for you. So there are many use cases to use GraphQL and OPA API as well. This won't be a replacement for them, so it can be a good solution in some contexts.

Nice, yeah. Always use the best tool for the job. There is no one silver bullet or magic hammer. And always it depends. It depends, of course. Does TRPC provide a runtime type check or the validation of data coming into the API? Yeah, this is a part that I need to skip for the timing. But when you call a mutation, you have in the input object of course, if I want to add an author I need to pass first name, last name, and in this case, the country. And then you have Zod and many other libraries for validation the input, and throw an exception and notify you that you are passing something wrong. So Zod is at the base layer for TRPC and there are many other validation libraries that can be useful in this case. It's incredible how much Zod has taken really like the TypeScript development world by storm because there's been libraries for this forever but I think Zod just gets something right about the API. It's just so friendly to use. It's really amazing. It's very nice. I use it for everything as well. It's wonderful.