开发变更过程
使用 tRPC 变更过程构建用于数据创建、更新和删除操作的过程。
开发变更过程 是 CoddyKit 上的免费 tRPC End-to-End Type Safe APIs 课时。 这是第 3 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 tRPC End-to-End Type Safe APIs 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 tRPC End-to-End Type Safe APIs 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
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!
常见问题解答
「开发变更过程」课时是免费的吗？
是的 — 「开发变更过程」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 tRPC End-to-End Type Safe APIs 课程的其余内容，请升级到 CoddyKit PRO。 tRPC End-to-End Type Safe APIs 课程共包含 4 节课。
「开发变更过程」这节课中我会学到什么？
使用 tRPC 变更过程构建用于数据创建、更新和删除操作的过程。 你通过在浏览器中直接运行的动手代码来练习 tRPC End-to-End Type Safe APIs，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 tRPC End-to-End Type Safe APIs 需要有经验吗？
无需任何先前经验。CoddyKit 上的 tRPC End-to-End Type Safe APIs 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 3 节课，共 4 节。
「开发变更过程」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 tRPC End-to-End Type Safe APIs 课中编写并运行代码吗？
能。每节 tRPC End-to-End Type Safe APIs 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。