apollo-graphql

Apollo GraphQL Best Practices

You are an expert in Apollo Client, GraphQL, TypeScript, and React development. Apollo Client provides a comprehensive state management solution for GraphQL applications with intelligent caching, optimistic UI updates, and seamless React integration.

Core Principles

• Use Apollo Client for state management and data fetching
• Implement query components for data fetching
• Utilize mutations for data modifications
• Use fragments for reusable query parts
• Implement proper error handling and loading states
• Leverage TypeScript for type safety with GraphQL operations

Project Structure

src/
  components/
  graphql/
    queries/
      users.ts
      posts.ts
    mutations/
      users.ts
      posts.ts
    fragments/
      user.ts
      post.ts
  hooks/
    useUser.ts
    usePosts.ts
  pages/
  utils/
    apollo-client.ts
  types/
    generated/           # Generated TypeScript types

Setup and Configuration

Apollo Client Setup

// utils/apollo-client.ts
import { ApolloClient, InMemoryCache, HttpLink, from } from '@apollo/client';
import { onError } from '@apollo/client/link/error';

const httpLink = new HttpLink({
  uri: process.env.NEXT_PUBLIC_GRAPHQL_ENDPOINT,
});

const errorLink = onError(({ graphQLErrors, networkError }) => {
  if (graphQLErrors) {
    graphQLErrors.forEach(({ message, locations, path }) => {
      console.error(`[GraphQL error]: Message: ${message}, Path: ${path}`);
    });
  }
  if (networkError) {
    console.error(`[Network error]: ${networkError}`);
  }
});

export const apolloClient = new ApolloClient({
  link: from([errorLink, httpLink]),
  cache: new InMemoryCache({
    typePolicies: {
      Query: {
        fields: {
          users: {
            merge(existing = [], incoming) {
              return [...existing, ...incoming];
            },
          },
        },
      },
    },
  }),
  defaultOptions: {
    watchQuery: {
      fetchPolicy: 'cache-and-network',
      errorPolicy: 'all',
    },
    query: {
      fetchPolicy: 'cache-first',
      errorPolicy: 'all',
    },
    mutate: {
      errorPolicy: 'all',
    },
  },
});