Apollo Client Patterns

Quick Guide: Apollo stores every entity once, keyed by __typename plus its keyFields, and re-renders everything watching it. Most of the difficulty is in the cache rather than the hooks: keyFields decides identity, keyArgs decides how many cache entries a paginated field gets, and an optimistic response missing __typename fails to normalize without saying so. v3.9 added the Suspense hooks; v4 moved the React hooks to @apollo/client/react and typed the error classes.

Detailed Resources:

• examples/core.md — codegen config, client and link chain, useQuery, useLazyQuery, mutations with cache updates
• examples/pagination.md — fetchMore with an observer, relay and offset type policies
• examples/fragments.md — fragment definition, composition and use in queries
• examples/error-handling.md — partial data rendering, global error link
• examples/subscriptions.md — split link over graphql-ws, useSubscription writing to cache
• examples/suspense.md — useSuspenseQuery, useLoadableQuery, useBackgroundQuery, createQueryPreloader
• examples/testing.md — MockedProvider, mock shapes, asserting cache updates, schema-based testing
• reference.md — fetch/error policy, network status and cache method tables, v3 → v4 migration