tRPC End-to-End Type Safe APIs · Lektion

Mutation-Prozeduren entwickeln

Erstellen Sie mit tRPC-Mutation-Prozeduren Prozeduren zum Anlegen, Aktualisieren und Löschen von Daten.

Mutation-Prozeduren entwickeln ist eine kostenlose tRPC End-to-End Type Safe APIs-Lektion auf CoddyKit. Dies ist Lektion 3 von 4. Du kannst die komplette Lektion unten kostenlos lesen – dann übst du sie direkt im Browser mit einem integrierten Code-Editor und einem KI-Tutor rund um die Uhr. Sie ist Teil des tRPC End-to-End Type Safe APIs-Lernpfads, und dein Fortschritt wird über Web und CoddyKit-App synchronisiert. Der tRPC End-to-End Type Safe APIs-Kurs umfasst insgesamt 4 Lektionen.

Teile dieser Lektion wurden noch nicht übersetzt und werden auf Englisch angezeigt.

What Are tRPC Mutations?

Welcome to tRPC mutation procedures! So far, you've likely used queries to fetch data, like getting a list of users or a single product.

But what if you need to change data? This is where mutations come in. Mutations are API operations designed to modify data on your server.

Create: Add new records (e.g., create a user).
Update: Modify existing records (e.g., update a user's email).
Delete: Remove records (e.g., delete a user).

They are the 'CUD' in CRUD operations!

Mutations vs. Queries

It's important to understand the difference between queries and mutations in tRPC:

Queries: Used for fetching data. They are typically read-only and should not have side effects (i.e., they don't change data on the server).
Mutations: Used for changing data. They are designed to have side effects and modify your server's state.

tRPC enforces this separation, helping you build more predictable and robust APIs. When you need to create, update, or delete anything, always reach for a mutation.

Defining a Simple Mutation

Let's start by defining a very simple mutation. Just like queries, mutations are procedures within your tRPC router.

We use .mutation() instead of .query(). This example takes a name as input and returns a greeting string.

import { initTRPC } from '@trpc/server';
import { z } from 'zod';

const t = initTRPC.create();

const appRouter = t.router({
  sayHello: t.procedure
    .input(z.object({ name: z.string() }))
    .mutation(({ input }) => {
      // In a real app, this might save 'name' to a log
      return `Hello, ${input.name}!`;
    }),
});

export type AppRouter = typeof appRouter;
// This defines a valid tRPC router with one mutation.

Creating Data: The 'Create' Mutation

A common use case for mutations is creating new data. Let's build a createUser mutation that accepts a user's name and email.

We'll use zod (a schema validation library) to define the expected input structure. This ensures type safety and validates incoming data automatically.

import { initTRPC } from '@trpc/server';
import { z } from 'zod';

const t = initTRPC.create();

interface User {
  id: string;
  name: string;
  email: string;
}
const users: User[] = []; // Our 'database'

const appRouter = t.router({
  createUser: t.procedure
    .input(z.object({
      name: z.string().min(1),
      email: z.string().email(),
    }))
    .mutation(({ input }) => {
      const newUser: User = {
        id: `user-${users.length + 1}`,
        name: input.name,
        email: input.email,
      };
      users.push(newUser); // Add to our fake database
      return newUser; // Return the new user object
    }),
});

export type AppRouter = typeof appRouter;
// This router defines how to create a user.

Updating Data: The 'Update' Mutation

Next, let's tackle updating existing data. An updateUser mutation will need the id of the user to update, plus the fields that need changing.

Notice how we can make fields .optional() in our Zod schema if they might not always be provided during an update.

import { initTRPC } from '@trpc/server';
import { z } from 'zod';

const t = initTRPC.create();

interface User {
  id: string;
  name: string;
  email: string;
}
const users: User[] = [
  { id: 'user-1', name: 'Alice', email: 'alice@example.com' },
];

const appRouter = t.router({
  updateUser: t.procedure
    .input(z.object({
      id: z.string(),
      name: z.string().min(1).optional(),
      email: z.string().email().optional(),
    }))
    .mutation(({ input }) => {
      const userIndex = users.findIndex(u => u.id === input.id);
      if (userIndex === -1) {
        throw new Error('User not found');
      }
      // Merge existing data with new input
      users[userIndex] = { ...users[userIndex], ...input };
      return users[userIndex]; // Return the updated user
    }),
});

export type AppRouter = typeof appRouter;
// This router defines how to update a user.

Deleting Data: The 'Delete' Mutation

Finally, let's create a mutation to delete data. A deleteUser mutation typically only needs the id of the record to remove.

For the return value, you might send back a simple success message or the ID of the deleted item. Here, we'll return a boolean indicating success.

import { initTRPC } from '@trpc/server';
import { z } from 'zod';

const t = initTRPC.create();

interface User {
  id: string;
  name: string;
  email: string;
}
const users: User[] = [
  { id: 'user-1', name: 'Alice', email: 'alice@example.com' },
  { id: 'user-2', name: 'Bob', email: 'bob@example.com' },
];

const appRouter = t.router({
  deleteUser: t.procedure
    .input(z.object({ id: z.string() }))
    .mutation(({ input }) => {
      const initialLength = users.length;
      const userIndex = users.findIndex(u => u.id === input.id);
      if (userIndex !== -1) {
        users.splice(userIndex, 1); // Remove from array
      }
      // Return true if an item was removed
      return { success: users.length < initialLength };
    }),
});

export type AppRouter = typeof appRouter;
// This router defines how to delete a user.

Client-Side Mutation Calls

Now that you've defined your mutations on the server, how do you call them from your frontend application?

Using the tRPC client, you simply access the mutation by its name and call the .mutate() method, passing your input data.

import { createTRPCProxyClient, httpBatchLink } from '@trpc/client';

// A simplified AppRouter type for this client-side example.
// In a real app, you'd import 'AppRouter' from your shared types.
interface User { id: string; name: string; email: string; }
type AppRouter = {
  sayHello: (input: { name: string }) => Promise<string>;
  createUser: (input: { name: string; email: string }) => Promise<User>;
  deleteUser: (input: { id: string }) => Promise<{ success: boolean }>;
};

const trpc = createTRPCProxyClient<AppRouter>({
  links: [
    httpBatchLink({
      url: 'http://localhost:3000/trpc', // Your tRPC server URL
    }),
  ],
});

async function runMutationCalls() {
  console.log('1. Calling sayHello...');
  const helloRes = await trpc.sayHello.mutate({ name: 'Coddy' });
  console.log(`Result: ${helloRes}`);

  console.log('2. Calling createUser...');
  const newUser = await trpc.createUser.mutate({
    name: 'Eve',
    email: 'eve@example.com',
  });
  console.log('Created:', newUser);

  console.log('3. Calling deleteUser...');
  const deleteRes = await trpc.deleteUser.mutate({ id: newUser.id });
  console.log('Deleted:', deleteRes.success);
}

runMutationCalls();
// This script simulates client-side mutation calls.

Handling Results and Errors

When you call a mutation from the client, it returns a Promise. You can use await to wait for the result, just like with any asynchronous operation.

For error handling, you can use standard JavaScript try...catch blocks around your .mutate() calls. tRPC will automatically propagate errors from your backend to the client.

try {
  const result = await trpc.createUser.mutate({ ... });
  // Handle success
} catch (error) {
  // Handle error
  console.error('Mutation failed:', error.message);
}

This makes error management straightforward and type-safe.

When to Use Mutations

Remember to use mutations for any operation that changes data on your server. This includes:

Submitting a form (e.g., user registration, posting a comment).
Toggling a setting (e.g., dark mode preference).
Performing administrative actions (e.g., banning a user).
Uploading files (though this can involve special handling).

By consistently using mutations for these actions, you maintain clarity, type safety, and leverage tRPC's powerful features for data modification.

Check Your Mutation Knowledge

You've learned how to define and use tRPC mutation procedures. Time for a quick check!

Recap: Mutation Procedures

Great job! In this lesson, you've mastered tRPC mutation procedures:

You learned that mutations are for operations that change data (Create, Update, Delete).
You saw how to define mutations using t.procedure.mutation() with input validation via Zod.
You built examples for creating, updating, and deleting data on the server.
You understood how to call these mutations from the client and handle their results.

Mutations are a core part of building interactive and data-driven applications with tRPC. Next, we'll explore input validation more deeply with Zod!

Häufig gestellte Fragen

Ist die Lektion „Mutation-Prozeduren entwickeln“ kostenlos?

Ja — der vollständige Text von „Mutation-Prozeduren entwickeln“ ist hier im Web kostenlos zu lesen. Um sie interaktiv zu üben (integrierter Code-Editor und 24/7 KI-Tutor) und den Rest des tRPC End-to-End Type Safe APIs-Kurses freizuschalten, upgrade auf CoddyKit PRO. Der tRPC End-to-End Type Safe APIs-Kurs umfasst insgesamt 4 Lektionen.

Was lerne ich in „Mutation-Prozeduren entwickeln“?

Erstellen Sie mit tRPC-Mutation-Prozeduren Prozeduren zum Anlegen, Aktualisieren und Löschen von Daten. Du übst tRPC End-to-End Type Safe APIs mit praktischem Code, den du direkt im Browser ausführst, und ein 24/7 KI-Tutor beantwortet deine Fragen während du die Lektion bearbeitest.

Brauche ich Erfahrung, um tRPC End-to-End Type Safe APIs zu starten?

Keine Vorkenntnisse erforderlich. tRPC End-to-End Type Safe APIs auf CoddyKit ist für Anfänger bis fortgeschrittene Lernende strukturiert, sodass du hier starten oder von Anfang an beginnen und in deinem eigenen Tempo voranschreiten kannst. Dies ist Lektion 3 von 4.

Wie lange dauert die Lektion „Mutation-Prozeduren entwickeln“?

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