How to handle large local storage objects in Blazor Server?

Use the streaming implementation by registering AddBlazoredLocalStorageStreaming() in services and adding the JavaScript file to App.razor. This bypasses SignalR size limits but requires extra setup compared to standard usage.

Can I use synchronous local storage methods in Blazor Server?

No, synchronous methods via ISyncLocalStorageService are only supported in Blazor WebAssembly. In Blazor Server, you must use asynchronous APIs and call them in OnAfterRender to avoid pre-rendering issues.

Blazored LocalStorage vs direct JavaScript interop for local storage?

Blazored LocalStorage abstracts serialization and provides a type-safe C# interface, saving development time. Direct interop offers more control but requires manual JSON handling and lacks built-in testing utilities.

How to upgrade from v3 to v4 without breaking existing data?

Configure JsonSerializerOptions when adding services to match v3 settings, such as setting PropertyNamingPolicy to CamelCase and other options listed in the README, to ensure data compatibility.

Is Blazored LocalStorage secure for storing sensitive data?

No, it relies on browser local storage which is unencrypted and vulnerable to XSS attacks. It's designed for non-sensitive data like user preferences; for sensitive info, consider secure storage alternatives.

How to test Blazor components that use Blazored LocalStorage with bUnit?

Install the Blazored.LocalStorage.TestExtensions package and use AddBlazoredLocalStorage() in your test context to mock local storage, enabling simulation of storage operations in unit tests without browser dependencies.

Open-Awesome

Blazored.LocalStorage

MITC#v4.5.0

A library providing access to browser local storage with automatic serialization for Blazor applications.

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1.3k stars134 forks0 contributors

What is Blazored.LocalStorage?

Blazored LocalStorage is a library that provides Blazor applications with access to the browser's local storage API. It handles the serialization and deserialization of data automatically, allowing developers to persist application state between sessions without manual JSON conversion. The library supports both Blazor WebAssembly and Blazor Server, with APIs for asynchronous and synchronous operations.

Target Audience

Blazor developers who need to persist client-side data, such as user preferences, form inputs, or application state, across browser sessions in a simple and efficient manner.

Value Proposition

Developers choose Blazored LocalStorage because it abstracts the complexities of the browser's local storage API, provides automatic serialization, and offers a clean, type-safe interface integrated with Blazor's dependency injection and lifecycle. Its support for custom serializers and testing utilities makes it a robust choice for production applications.

Overview

A library to provide access to local storage in Blazor applications

Use Cases

Best For

Persisting user preferences and settings in Blazor WebAssembly apps
Storing form data locally to prevent loss on page refresh
Caching API responses or computed data client-side in Blazor applications
Managing client-side application state across browser sessions
Testing Blazor components that interact with local storage using bUnit
Handling large data objects in Blazor Server with streaming support

Not Ideal For

Applications requiring synchronous local storage access in Blazor Server hosting models
Projects with strict backward compatibility needs that cannot tolerate breaking changes in serialization formats
Teams looking for a zero-configuration solution for handling large data objects in Blazor Server
Non-Blazor .NET projects that need client-side storage solutions

Pros & Cons

Pros

Automatic Serialization

Handles all serialization and deserialization automatically when saving or retrieving values, eliminating manual JSON handling and reducing boilerplate code.

Dual API Flexibility

Provides both asynchronous ILocalStorageService and synchronous ISyncLocalStorageService interfaces, catering to different Blazor hosting models and use cases, with sync methods available in WebAssembly.

Streaming for Large Data

Offers a streaming implementation for Blazor Server to bypass SignalR message size limits (default 32KB), enabling storage of large objects without data loss.

Integrated Testing Support

Includes bUnit test extensions via the Blazored.LocalStorage.TestExtensions package, allowing easy mocking of local storage for realistic component testing.

Cons

Breaking Serialization Changes

Version 4 introduced breaking changes to JSON serializer defaults, which can corrupt data stored with v3 and requires manual configuration to maintain compatibility, as detailed in the README.

Sync API Limited to WebAssembly

Synchronous operations are only available in Blazor WebAssembly; Blazor Server developers must use async methods, complicating code in scenarios where sync access is preferred.

Additional Setup for Streaming

To use streaming in Blazor Server, developers must register special services with AddBlazoredLocalStorageStreaming() and add a JavaScript file, adding extra steps beyond basic configuration.

Frequently Asked Questions

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