@apollo/client

What is @apollo/client?

The @apollo/client npm package is a comprehensive state management library for JavaScript that enables you to manage both local and remote data with GraphQL. It is designed to help you develop faster and more secure apps with less boilerplate. It integrates seamlessly with any JavaScript front-end, allowing for reactive data fetching, caching, and data management.

What are @apollo/client's main functionalities?

Fetching data with useQuery

This feature allows you to fetch data from a GraphQL server. The useQuery hook is used to execute a GraphQL query and handle loading, error, and result states.

import { useQuery, gql } from '@apollo/client';

const GET_LAUNCHES = gql`
  query GetLaunches {
    launches {
      id
      mission_name
    }
  }
`;

function Launches() {
  const { loading, error, data } = useQuery(GET_LAUNCHES);

  if (loading) return <p>Loading...</p>;
  if (error) return <p>Error :(</p>;

  return data.launches.map(({ id, mission_name }) => (
    <div key={id}>
      <p>{mission_name}</p>
    </div>
  ));
}

Updating data with useMutation

This feature enables you to update data on a GraphQL server. The useMutation hook is used to execute a mutation, allowing you to create, update, or delete data.

import { useMutation, gql } from '@apollo/client';

const ADD_TODO = gql`
  mutation AddTodo($type: String!) {
    addTodo(type: $type) {
      id
      type
    }
  }
`;

function AddTodo() {
  let input;
  const [addTodo, { data }] = useMutation(ADD_TODO);

  return (
    <div>
      <form
        onSubmit={e => {
          e.preventDefault();
          addTodo({ variables: { type: input.value } });
          input.value = '';
        }}
      >
        <input
          ref={node => {
            input = node;
          }}
        />
        <button type="submit">Add Todo</button>
      </form>
    </div>
  );
}

Managing local state

This feature allows you to manage local state using Apollo Client. You can read and write to the cache as if it were a local database, enabling you to manage client-side state alongside remote data.

import { gql, useApolloClient } from '@apollo/client';

const GET_LOCAL_STATE = gql`
  query GetLocalState {
    isLoggedIn @client
  }
`;

function LoginButton() {
  const client = useApolloClient();
  const data = client.readQuery({ query: GET_LOCAL_STATE });
  const isLoggedIn = data.isLoggedIn;

  return (
    <button onClick={() => {
      client.writeQuery({
        query: GET_LOCAL_STATE,
        data: { isLoggedIn: !isLoggedIn }
      });
    }}>
      {isLoggedIn ? 'Log out' : 'Log in'}
    </button>
  );
}

Other packages similar to @apollo/client

relay

Relay is a JavaScript framework for building data-driven React applications with GraphQL. It is similar to @apollo/client in that it provides a powerful and efficient way to fetch and manage GraphQL data. Relay focuses on performance optimizations and static query generation, which can make it more suitable for complex, large-scale applications with high performance requirements.

urql

urql is a highly customizable and versatile GraphQL client for React, Vue, Svelte, and other JavaScript frameworks. It offers a simpler and more flexible approach compared to @apollo/client, with features like document caching and subscriptions. urql's extensibility and plugin system make it a good choice for developers looking for a lightweight and adaptable GraphQL client.

README

Apollo Client

Apollo Client is a fully-featured caching GraphQL client with integrations for React, Angular, and more. It allows you to easily build UI components that fetch data via GraphQL.

Documentation

All Apollo Client documentation, including React integration articles and helpful recipes, can be found at:
https://www.apollographql.com/docs/react/

The Apollo Client API reference can be found at:
https://www.apollographql.com/docs/react/api/apollo-client/

Maintainers

• @benjamn (Apollo)
• @hwillson (Apollo)