Offline-first app with GraphQL: React Relay vs. URQL

— A too good answer from perplexity.ai not to share, so here it is:

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Here’s a comparison of using React Relay (with or without react-relay-offline) versus Urql with Graphcache for building offline-first apps:

React Relay (Manual or with react-relay-offline)

Pros:

• Relay’s Strengths: Built for GraphQL with optimized performance and normalized caching out of the box.
• Customizability (Manual): Full control over offline persistence, mutation queuing, and cache management when implementing manually.
• Out-of-the-Box Offline Support (react-relay-offline): Simplifies offline functionality with features like mutation queuing, retries, and cache persistence.
• Optimistic Updates: Easy to implement optimistic responses for better user experience during offline operations.

Cons:

• Complexity (Manual): Manual implementation requires significant effort to handle caching, persistence, and retries.
• Bundle Size (react-relay-offline): Adds ~16.4 kB to the app size.
• Learning Curve: React Relay has a steeper learning curve compared to Urql due to its strict architecture and reliance on GraphQL fragments.

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Urql with Graphcache

Pros:

• Modular Design: Urql’s exchange-based architecture allows flexibility in adding offline support using the offlineExchange from Graphcache.
• Graphcache Features: Provides normalized caching, automatic updates based on schema, and offline persistence through storage layers like AsyncStorage or IndexedDB (learn more about @urql/storage-rn).
• Simplified Setup: Adding offline support is straightforward by configuring offlineExchange with storage (e.g., @urql/storage-rn for React Native) (check out this tutorial).
• Optimistic Updates: Supports optimistic responses and cache updates for seamless offline behavior.

Cons:

• Custom Logic for Mutations: Offline mutations may require more manual handling (e.g., queuing failed mutations) compared to libraries like react-relay-offline.
• Limited Offline Mutation Handling: Mutations are only optimistically updated locally; if the server is unreachable during retries, changes may not persist unless custom logic is added (see discussion on Urql and learn how to handle mutations offline).
• Schema Dependency: Requires a well-defined schema for effective caching and updates.

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Key Differences

Feature	React Relay (Manual)	React Relay (react-relay-offline)	Urql with Graphcache
Ease of Setup	High complexity	Medium complexity	Low complexity
Offline Query Caching	Manual setup	Automatic	Automatic
Mutation Queuing & Retry	Manual implementation	Built-in	Requires custom handling (see how to handle mutations)
Persistence Options	Custom storage logic needed	Pre-configured options	Pre-configured options
Optimistic Updates	Manual	Built-in	Built-in
Network Monitoring	Manual	Built-in hooks	Built-in
Customization	Full	Moderate	High
Bundle Size Impact	Minimal	+16.4 kB	Minimal

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Recommendation

1. Use React Relay with react-relay-offline if:

   • You are already using React Relay and need robust offline support with minimal additional setup.
   • You require built-in mutation queuing and retry mechanisms.

2. Use Urql with Graphcache if:

   • You prefer a lightweight, modular library with flexibility in customizing exchanges.
   • Your app primarily focuses on query caching and optimistic updates but can handle custom logic for mutation retries.

3. Choose Manual React Relay Implementation if:

   • You need full control over every aspect of offline functionality without relying on third-party libraries.

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Why Relay is sometimes superior to URQL

Relay is often considered superior to URQL for complex React applications due to its advanced features and optimizations:

• Performance: Relay's compiler pre-optimizes queries for runtime efficiency, ensuring high performance as applications scale (learn more about Relay's performance).

• Declarative Data Fetching: Relay allows developers to declare data dependencies in components, automating data fetching and reducing boilerplate (see Relay's declarative approach).

• Type Safety: It auto-generates TypeScript/Flow types, ensuring schema consistency and reducing runtime errors (explore Relay's type safety features).

• Built-in Features: Relay provides out-of-the-box support for caching, pagination, optimistic updates, and conflict resolution, which URQL lacks natively (discover Relay's built-in features).

• Strict Conventions: Relay enforces GraphQL best practices, ensuring reliable APIs and clean architecture (understand Relay's conventions).

However, Relay has a steeper learning curve and requires stricter schema design, making URQL a simpler choice for smaller or less demanding projects (compare Relay and URQL for different project sizes).

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Built-in Features in Relay (Point 4 Expanded)

Relay stands out because it provides robust, built-in features that simplify complex GraphQL workflows. These features are designed to handle common challenges in data fetching and state management, reducing the need for additional libraries or custom implementations. Here's a detailed breakdown of these features:

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1. Caching

Relay includes a sophisticated normalized cache out of the box. This means that data fetched from the server is stored in a normalized format, where each entity is stored by its unique identifier. This allows Relay to:

• Efficiently update only the parts of the UI that are affected by changes in the data.
• Avoid redundant network requests by reusing cached data whenever possible.
• Automatically merge new data into the cache without manual intervention.

Relay's cache is highly optimized and works seamlessly with its compiler, ensuring minimal runtime overhead.

In contrast, while URQL has a caching layer (via its @urql/exchange-graphcache package), it requires additional configuration and doesn't offer the same level of integration or performance optimization as Relay's built-in solution.

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2. Pagination

Relay provides automatic pagination support for GraphQL connections (a common pattern for paginated data in GraphQL). It includes:

• Relay-style Cursor-based Pagination: Relay is designed around GraphQL's connection model, making it easy to implement infinite scrolling or "load more" functionality.
• Automatic Cache Updates: When fetching additional pages, Relay automatically updates the cache and merges new results with existing data without requiring manual intervention.

URQL does not have native pagination support. Developers often need to write custom logic or use third-party libraries to handle pagination effectively.

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3. Optimistic Updates

Relay supports optimistic updates out of the box, allowing developers to update the UI immediately after a mutation is triggered, even before receiving a response from the server. This creates a smoother user experience by reducing perceived latency.

For example:

• If a user submits a form, Relay can optimistically update the UI as if the mutation succeeded.
• If the mutation fails, Relay will roll back the optimistic update automatically.

While URQL also supports optimistic updates, it requires more manual configuration compared to Relay's seamless integration with its store and cache.

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4. Conflict Resolution

Relay includes mechanisms for handling data conflicts that may arise when multiple operations (e.g., mutations) affect overlapping parts of the cache. For example:

• If two components request overlapping fields from the same object, Relay ensures that both components receive consistent and up-to-date data.
• When mutations are performed, Relay intelligently updates only the affected parts of the cache without overwriting unrelated fields.

This conflict resolution is tightly integrated with Relay's normalized cache and compiler-generated artifacts, making it reliable and efficient.

URQL does not provide built-in conflict resolution mechanisms, leaving developers to handle such scenarios manually.

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5. Subscriptions

Relay supports GraphQL subscriptions for real-time updates via third-party extensions or libraries (e.g., subscriptions-transport-ws or graphql-ws). Subscriptions integrate well with its caching layer, ensuring that real-time data updates are reflected throughout your application automatically.

URQL also supports subscriptions but requires additional setup using its @urql/exchange-subscription package. However, integrating subscriptions with URQL's cache can be more challenging compared to Relay's seamless approach.

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Summary

Relay's built-in features like caching, pagination, optimistic updates, and conflict resolution are tightly integrated into its architecture. This makes it an excellent choice for large-scale applications where managing complex GraphQL workflows efficiently is critical. While URQL can achieve similar functionality with add-ons and custom logic, it requires more effort and lacks the deep integration and optimizations that Relay offers out of the box.