Sviluppare procedure di mutation
Crei procedure per le operazioni di creazione, aggiornamento ed eliminazione dei dati usando le procedure di mutation tRPC.
Sviluppare procedure di mutation è una lezione tRPC End-to-End Type Safe APIs gratuita su CoddyKit. Questa è la lezione 3 di 4. Puoi leggere la lezione completa qui gratuitamente — poi esercitati direttamente nel browser con un editor di codice integrato e un tutor IA disponibile 24/7. Fa parte del percorso di apprendimento tRPC End-to-End Type Safe APIs, e i tuoi progressi si sincronizzano tra il web e l'app CoddyKit. Il corso tRPC End-to-End Type Safe APIs include 4 lezioni in totale.
Parti di questa lezione non sono ancora state tradotte e vengono mostrate in inglese.
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!
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Crei procedure per le operazioni di creazione, aggiornamento ed eliminazione dei dati usando le procedure di mutation tRPC. Eserciti tRPC End-to-End Type Safe APIs con codice pratico che esegui direttamente nel browser, e un tutor IA 24/7 risponde alle tue domande mentre lavori sulla lezione.
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Tutte le lezioni di questo corso
- Strutturare il codice con i router tRPC
- Implementare procedure di query
- Sviluppare procedure di mutation
- Unire e annidare i router