tRPC機能の拡張
カスタムビルダーやプラグイン、他のライブラリとの統合によってtRPCを拡張する高度な方法を学びます。
「tRPC機能の拡張」はCoddyKit上の無料tRPC End-to-End Type Safe APIsレッスンです。 これはレッスン3/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはtRPC End-to-End Type Safe APIs学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 tRPC End-to-End Type Safe APIsコースには全4レッスンが含まれています。
このレッスンの一部はまだ翻訳されておらず、英語で表示されています。
Extend tRPC's Core
tRPC is incredibly powerful out-of-the-box, but sometimes your application needs more custom control and specialized behavior. This lesson will show you how to extend tRPC beyond basic middleware.
We'll explore custom procedure builders for creating specialized API endpoints and discuss how to integrate tRPC seamlessly with other libraries like ORMs.
Why Custom Builders?
Standard middleware is great for applying common logic to all or a group of procedures, such as authentication or logging.
But what if you need to define specific types of procedures, like adminProcedure or publicProcedure, each with unique context properties or pre-configured middleware chains? Custom procedure builders are perfect for this!
Crafting a Builder with `createBuilder`
tRPC provides the createBuilder utility to help you define your own procedure factory. This builder can extend the context (ctx), add metadata, or apply middleware automatically to any procedure built with it.
It allows you to abstract common setup logic into a reusable pattern, making your API definitions cleaner and more consistent.
Builder Example: Admin Procedure
Let's create an adminProcedure. This builder ensures the user is not only logged in (via protectedProcedure) but also has an isAdmin flag set in their context. This logic is then automatically applied to any procedure using adminProcedure.
// Minimal tRPC-like setup for demonstration
type Context = { user?: { id: number; isAdmin?: boolean } };
const mockProcedure = {
use: (middleware: any) => ({
use: (nextMiddleware: any) => ({
_isBuilder: true,
_middlewares: [middleware, nextMiddleware]
}),
_isBuilder: true,
_middlewares: [middleware]
}),
_isBuilder: true,
_middlewares: []
};
const t = {
procedure: mockProcedure
};
// --- Actual tRPC Builder Code ---
const protectedProcedure = t.procedure.use(async ({ ctx, next }: any) => {
if (!ctx.user) {
throw new Error('Not authenticated');
}
return next({ ctx: { ...ctx, user: ctx.user } });
});
const adminProcedure = protectedProcedure.use(async ({ ctx, next }: any) => {
if (!ctx.user?.isAdmin) {
throw new Error('Not an admin!');
}
return next({ ctx: { ...ctx, user: ctx.user } });
});
console.log("Protected procedure builder defined.");
console.log("Admin procedure builder defined.");
console.log("Admin procedure has " + adminProcedure._middlewares.length + " middlewares.");Benefits of Custom Builders
Custom builders offer several significant advantages:
- Reusability: Define complex logic once and apply it across many procedures.
- Type Safety: Enforce specific context types for groups of procedures.
- Readability: Procedures become self-documenting (e.g.,
adminProcedure.query(...)clearly indicates its requirements). - Consistency: Ensure all procedures of a certain type adhere to specific rules and checks.
Integration with External Libraries
tRPC is unopinionated about your data layer. This means you can easily integrate it with any ORM (like Prisma, Drizzle), database client, or external API service you prefer.
The key to this seamless integration is often to initialize instances of these clients and attach them to your tRPC context. This makes them readily available to all your procedures.
Contextualizing an ORM (Prisma)
A very common pattern in tRPC applications is to initialize your ORM client (e.g., Prisma Client) and then attach that instance to your tRPC context object.
This allows all your tRPC procedures to access the database client via ctx.prisma, centralizing its management and providing type safety.
// Minimal tRPC-like setup for demonstration
type MockPrismaClient = {
user: {
findUnique: (args: { where: { id: number } }) => { id: number; name: string } | null;
};
};
type ContextWithPrisma = {
prisma: MockPrismaClient;
};
const mockProcedure = {
query: (handler: (opts: { ctx: ContextWithPrisma }) => any) => ({
_handler: handler,
_isQuery: true
})
};
const t = {
procedure: mockProcedure
};
// --- Actual tRPC Context Integration ---
const publicProcedure = t.procedure;
const getUserProcedure = publicProcedure.query(async ({ ctx }) => {
const user = await ctx.prisma.user.findUnique({ where: { id: 1 } });
return user ? `User name: ${user.name}` : 'User not found.';
});
// --- Demonstration (conceptual execution) ---
const mockPrisma: MockPrismaClient = {
user: {
findUnique: (args) => {
if (args.where.id === 1) {
return { id: 1, name: 'Alice' };
}
return null;
}
}
};
const mockContext: ContextWithPrisma = { prisma: mockPrisma };
console.log("Prisma client attached to context type.");
console.log("Conceptual handler output for user 1:");
console.log(await getUserProcedure._handler({ ctx: mockContext }));The Power of Plugins (Conceptual)
Beyond builders, tRPC offers an experimental createTRPCPlugin API. Plugins provide even deeper hooks into tRPC's internals, allowing you to customize error formatting, add custom data transformers, or modify the request lifecycle in advanced ways.
They are designed for truly complex, core-level extensions that affect how tRPC operates at a foundational level.
When to Use What?
Choosing between custom builders and plugins depends on your extension needs:
- Custom Builders: Best for defining specific types of procedures, enriching the context object, or applying common middleware chains. They operate at the procedure definition level.
- Plugins: Ideal for modifying tRPC's core behavior, such as custom error handling, data serialization/deserialization, or integrating with external systems at a global, foundational level.
Quick Check
Which of the following are key benefits of using custom tRPC procedure builders?
Summary of Extensions
In this lesson, we explored how to extend tRPC's capabilities. We learned to use custom procedure builders to create specialized, reusable procedures like adminProcedure, enhancing reusability, type safety, and consistency.
We also saw how to integrate external libraries like ORMs by attaching them to the tRPC context. Finally, we touched upon the advanced potential of tRPC plugins for deeper core modifications. These tools empower you to tailor tRPC to your application's unique needs.
よくある質問
「tRPC機能の拡張」レッスンは無料ですか？
はい。「tRPC機能の拡張」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、tRPC End-to-End Type Safe APIsコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 tRPC End-to-End Type Safe APIsコースには全4レッスンが含まれています。
「tRPC機能の拡張」で何を学びますか？
カスタムビルダーやプラグイン、他のライブラリとの統合によってtRPCを拡張する高度な方法を学びます。 ブラウザで直接実行するハンズオンコードでtRPC End-to-End Type Safe APIsを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。
tRPC End-to-End Type Safe APIsを始めるのに経験は必要ですか？
事前経験は必要ありません。CoddyKitのtRPC End-to-End Type Safe APIsは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン3/4です。
「tRPC機能の拡張」レッスンにはどのくらい時間がかかりますか？
ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。
このtRPC End-to-End Type Safe APIsレッスンでコードを書いて実行できますか？
はい。すべてのtRPC End-to-End Type Safe APIsレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。