Archiviazione locale e IndexedDB
Utilizzi meccanismi di archiviazione simili a quelli del browser, come `localStorage` e `IndexedDB`, per la persistenza dei dati lato client nella vostra app Electron.
Archiviazione locale e IndexedDB è una lezione Electron Desktop App Development gratuita su CoddyKit. Questa è la lezione 1 di 3. 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 Electron Desktop App Development, e i tuoi progressi si sincronizzano tra il web e l'app CoddyKit. Il corso Electron Desktop App Development include 3 lezioni in totale.
Parti di questa lezione non sono ancora state tradotte e vengono mostrate in inglese.
Saving Data in Electron Apps
When building desktop applications with Electron, you often need to save user data or application settings. This is called data persistence.
Unlike web apps that rely on servers, Electron apps can store data directly on the user's computer. This lesson explores two common browser-like storage methods: localStorage and IndexedDB.
Introducing Web Storage API
Electron's renderer processes are essentially web browsers. This means you can use standard browser APIs for data storage, like the Web Storage API.
The Web Storage API provides two main types:
localStorage: Stores data with no expiration date.sessionStorage: Stores data only for the duration of the browser session.
We'll focus on localStorage for persistent data.
Understanding localStorage
localStorage allows you to store data as simple key-value pairs. Think of it like a small, local dictionary.
- Persistence: Data stored in
localStorageremains even after the app is closed and reopened. - Scope: Data is unique to the origin (your app's domain, usually
file://for Electron). - Capacity: Limited to about 5-10 MB per origin.
It's great for small amounts of data like user preferences or simple settings.
Storing Data with localStorage
You can store data in localStorage using the setItem() method. Remember, values are always stored as strings.
Try running this example in your renderer process:
/* This code runs in the Electron renderer process. */
const username = "CoddyKitUser";
localStorage.setItem("userName", username);
const userSettings = {
theme: "dark",
notifications: true
};
// Objects need to be converted to JSON strings
localStorage.setItem("appSettings", JSON.stringify(userSettings));
console.log("Data saved to localStorage!");Retrieving & Removing localStorage Data
To get data back, use getItem(). To delete, use removeItem(). If you stored an object, you'll need to parse it back from JSON.
Run this snippet after the previous one:
/* This code runs in the Electron renderer process. */
const storedUsername = localStorage.getItem("userName");
console.log("Stored Username:", storedUsername);
const storedSettingsString = localStorage.getItem("appSettings");
if (storedSettingsString) {
const storedSettings = JSON.parse(storedSettingsString);
console.log("Stored Theme:", storedSettings.theme);
}
// To remove an item:
localStorage.removeItem("userName");
console.log("Username removed.");
// To clear all localStorage for the origin:
// localStorage.clear();Limitations of localStorage
While easy to use, localStorage has some limitations:
- Size Limit: Typically 5-10 MB per origin. Not suitable for large datasets.
- String-Only: All data is stored as strings. Objects and arrays must be manually serialized (e.g., with
JSON.stringify()) and deserialized (JSON.parse()). - Synchronous: Operations block the main thread, which can cause UI freezes if you're storing/retrieving a lot of data.
- No Indexing/Querying: You can't directly query data, only access by key.
Introducing IndexedDB
For larger, more structured, and complex data, IndexedDB is a powerful alternative. It's a low-level API for client-side storage of significant amounts of structured data.
- No Size Limit: Generally limited only by available disk space.
- Structured Data: Can store JavaScript objects directly, not just strings.
- Asynchronous: Operations don't block the UI thread, making it suitable for performance-critical apps.
IndexedDB Core Concepts
IndexedDB works with a few key concepts:
- Databases: You create databases, each with a name and version.
- Object Stores: Like tables in a relational database, but they store JavaScript objects. Each object store has a key path.
- Indexes: For fast querying of data within an object store.
- Transactions: All read and write operations must occur within a transaction, ensuring data integrity.
- Asynchronous: Operations return
IDBRequestobjects, which resolve withsuccessorerrorevents (or Promises).
Basic IndexedDB Setup
Setting up IndexedDB involves opening a database and defining object stores. This is usually done in the renderer process.
This example shows how to open a database and create an object store if it doesn't exist:
/* This code runs in the Electron renderer process. */
const request = indexedDB.open("CoddyKitDB", 1); // DB name, version
request.onerror = (event) => {
console.error("Database error:", event.target.errorCode);
};
request.onsuccess = (event) => {
const db = event.target.result;
console.log("Database opened successfully!");
// You can now interact with the database (add/get data)
db.close(); // Close when done if not actively using
};
request.onupgradeneeded = (event) => {
// This runs if the database didn't exist or version changed
const db = event.target.result;
const objectStore = db.createObjectStore("users", { keyPath: "id" });
console.log("Object store 'users' created.");
// You can also create indexes here
objectStore.createIndex("name", "name", { unique: false });
};Quick Check on Storage
You've learned about localStorage and IndexedDB. Which statement accurately describes a key difference?
Recap: Local & IndexedDB
Great job! You've explored client-side data persistence in Electron:
localStorageis simple, synchronous, key-value storage for small, non-critical data.IndexedDBis a powerful, asynchronous, transactional database for large amounts of structured data.
Choosing between them depends on your data's size, structure, and performance needs. Both are crucial for building robust Electron applications that save user data locally.
Domande Frequenti
La lezione «Archiviazione locale e IndexedDB» è gratuita?
Sì — il testo completo di «Archiviazione locale e IndexedDB» è gratuito qui sul web. Per esercitarvi in modo interattivo (un editor di codice integrato e un tutor IA 24/7) e sbloccare il resto del corso Electron Desktop App Development, passa a CoddyKit PRO. Il corso Electron Desktop App Development include 3 lezioni in totale.
Cosa imparerò in «Archiviazione locale e IndexedDB»?
Utilizzi meccanismi di archiviazione simili a quelli del browser, come `localStorage` e `IndexedDB`, per la persistenza dei dati lato client nella vostra app Electron. Eserciti Electron Desktop App Development con codice pratico che esegui direttamente nel browser, e un tutor IA 24/7 risponde alle tue domande mentre lavori sulla lezione.
Ho bisogno di esperienza per iniziare Electron Desktop App Development?
Non è richiesta alcuna esperienza precedente. Electron Desktop App Development su CoddyKit è strutturato per principianti e studenti avanzati, quindi puoi iniziare da qui o dall'inizio e procedere al tuo ritmo. Questa è la lezione 1 di 3.
Quanto tempo richiede la lezione «Archiviazione locale e IndexedDB»?
La maggior parte delle lezioni CoddyKit richiede circa 5–10 minuti. Ogni lezione è breve e interattiva, quindi fai progressi costanti e riprendi esattamente da dove hai lasciato su web e app.
Posso scrivere ed eseguire codice in questa lezione Electron Desktop App Development?
Sì. Ogni lezione Electron Desktop App Development include un editor di codice integrato, quindi scrivi ed esegui codice reale direttamente nel tuo browser e ricevi feedback istantaneo dall'IA — nessuna configurazione locale necessaria.
Tutte le lezioni di questo corso
- Archiviazione locale e IndexedDB
- Accesso al file system
- Database incorporati con SQLite