README.md

graphql-hooks

? Minimal hooks-first GraphQL client.

Features

• ? First-class hooks API
• ⚖️Tiny bundle: only 5.1kB (1.9 gzipped)
• ? Full SSR support: see graphql-hooks-ssr
• ? Plugin Caching: see graphql-hooks-memcache
• ? No more render props hell
• ⏳ Handle loading and error states with ease

Install

npm install graphql-hooks

or

yarn add graphql-hooks

Support

• Latest 8 & 10 Node releases
• Browsers > 1%, not dead

Consider polyfilling:

• Promise
• fetch. NOTE: A custom implementation can also be provided instead of polyfilling, see GraphQLClient

Quick Start

First you'll need to create a client and wrap your app with the provider:

import { GraphQLClient, ClientContext } from 'graphql-hooks';

const client = new GraphQLClient({
  url: '/graphql'
});

function App() {
  return (
    <ClientContext.Provider value={client}>
      {/* children */}
    </ClientContext.Provider>
  );
}

Now in your child components you can make use of useQuery

import { useQuery } from 'graphql-hooks';

const HOMEPAGE_QUERY = `query HomePage($limit: Int) {
  users(limit: $limit) {
    id
    name
  }
}`;

function MyComponent() {
  const { loading, error, data } = useQuery(HOMEPAGE_QUERY, {
    variables: {
      limit: 10
    }
  });

  if (loading) return 'Loading...';
  if (error) return 'Something Bad Happened';

  return (
    <ul>
      {data.users.map(({ id, name }) => (
        <li key={id}>{name}</li>
      ))}
    </ul>
  );
}

Table of Contents

• API
  • GraphQLClient
  • ClientContext
  • useQuery
  • useManualQuery
  • useMutation
• Guides
  • SSR
  • Pagination
  • Authentication
  • Fragments
  • Migrating from Apollo

API

GraphQLClient

Usage:

import { GraphQLClient } from 'graphql-hooks';
const client = new GraphQLClient(config);

config: Object containing configuration properties

• url (Required): The url to your GraphQL server
• ssrMode: Boolean - set to true when using on the server for server-side rendering; defaults to false
• cache: Object with the following methods:
  • cache.get(key)
  • cache.set(key, data)
  • cache.delete(key)
  • cache.clear()
  • cache.keys()
  • getInitialState()
  • See graphql-hooks-memcache as a reference implementation
• fetch(url, options): Fetch implementation - defaults to the global fetch API
• fetchOptions: See MDN for info on what options can be passed
• headers: Object, e.g. { 'My-Header': 'hello' }
• logErrors: Boolean - defaults to true
• onError({ operation, result }): Custom error handler
  • operation: Object with query, variables and operationName
  • result: Object containing error, data, fetchError, httpError and graphqlErrors

client methods

• client.setHeader(key, value): Updates client.headers adding the new header to the existing headers
• client.setHeaders(headers): Replaces client.headers
• client.logErrorResult({ operation, result }): Default error logger; useful if you'd like to use it inside your custom onError handler
• request(operation, options): Make a request to your GraphQL server; returning a Promise
  • operation: Object with query, variables and operationName
• options.fetchOptionsOverrides: Object containing additional fetch options to be added to the default ones passed to new GraphQLClient(config)

ClientContext

ClientContext is the result of React.createContext() - meaning it can be used directly with React's new context API:

Example:

import { ClientContext } from 'graphql-hooks';
<ClientContext.Provider value={client}>
  {/* children can now consume the client context */}
</ClientContext.Provider>;

To access the GraphQLClient instance, call React.useContext(ClientContext):

import React, { useContext } from 'react';
import { ClientContext } from 'graphql-hooks';

function MyComponent() {
  const client = useContext(ClientContext);
}

useQuery

Usage:

const state = useQuery(query, [options]);

Example:

import { useQuery } from 'graphql-hooks';

function MyComponent() {
  const { loading, error, data } = useQuery(query);

  if (loading) return 'Loading...';
  if (error) return 'Something bad happened';

  return <div>{data.thing}</div>;
}

This is a custom hook that takes care of fetching your query and storing the result in the cache. It won't refetch the query unless query or options.variables changes.

• query: Your GraphQL query as a plain string
• options: Object with the following optional properties
  • variables: Object e.g. { limit: 10 }
  • operationName: If your query has multiple operations, pass the name of the operation you wish to execute.
  • useCache: Boolean - defaults to true; cache the query result
  • skipCache: Boolean - defaults to false; If true it will by-pass the cache and fetch, but the result will then be cached for subsequent calls. Note the refetch function will do this automatically
  • ssr: Boolean - defaults to true. Set to false if you wish to skip this query during SSR
  • fetchOptionsOverrides: Object - Specific overrides for this query. See MDN for info on what options can be passed
  • updateData(previousData, data): Function - Custom handler for merging previous & new query results; return value will replace data in useQuery return value
    • previousData: Previous GraphQL query or updateData result
    • data: New GraphQL query result

useQuery return value

const { loading, error, data, refetch, cacheHit, ...errors } = useQuery(QUERY);

• loading: Boolean - true if the query is in flight
• error: Boolean - true if fetchError or httpError or graphQLErrors has been set
• data: Object - the result of your GraphQL query
• refetch(options): Function - useful when refetching the same query after a mutation; NOTE this presets skipCache=true & will bypass the options.updateData function that was passed into useQuery. You can pass a new updateData into refetch if necessary.
  • options: Object - options that will be merged into the options that were passed into useQuery (see above).
• cacheHit: Boolean - true if the query result came from the cache, useful for debugging
• fetchError: Object - Set if an error occured during the fetch call
• httpError: Object - Set if an error response was returned from the server
• graphQLErrors: Array - Populated if any errors occured whilst resolving the query

useManualQuery

Use this when you don't want a query to automactially be fetched, or wish to call a query programmatically.

Usage:

const [queryFn, state] = useManualQuery(query, [options]);

Example:

import { useManualQuery } from 'graphql-hooks'

function MyComponent(props) {
  const [fetchUser, { loading, error, data }] = useManualQuery(GET_USER_QUERY, {
    variables: { id: props.userId }
  })

  return (
    <div>
      <button onClick={fetchUser}>Get User!</button>
      {error && <div>Failed to fetch user<div>}
      {loading && <div>Loading...</div>}
      {data && <div>Hello ${data.user.name}</div>}
    </div>
  )
}

If you don't know certain options when declaring the useManualQuery you can also pass the same options to the query function itself when calling it:

import { useManualQuery } from 'graphql-hooks';

function MyComponent(props) {
  const [fetchUser] = useManualQuery(GET_USER_QUERY);

  const fetchUserThenSomething = async () => {
    const user = await fetchUser({
      variables: { id: props.userId }
    });
    return somethingElse();
  };

  return (
    <div>
      <button onClick={fetchUserThenSomething}>Get User!</button>
    </div>
  );
}

useMutation

Mutations unlike Queries are not cached.

Usage:

const [mutationFn, state] = useMutation(mutation, [options]);

Example:

import { useMutation } from 'graphql-hooks';

const UPDATE_USER_MUTATION = `mutation UpdateUser(id: String!, name: String!) {
  updateUser(id: $id, name: $name) {
    name
  }
}`;

function MyComponent({ id, name }) {
  const [updateUser] = useMutation(UPDATE_USER_MUTATION);
  const [newName, setNewName] = useState(name);

  return (
    <div>
      <input
        type="text"
        value={newName}
        onChange={e => setNewName(e.target.value)}
      />
      <button
        onClick={() => updateUser({ variables: { id, name: newName } })}
      />
    </div>
  );
}

The options object that can be passed either to useMutation(mutation, options) or mutationFn(options) can be set with the following properties:

• variables: Object e.g. { limit: 10 }
• operationName: If your query has multiple operations, pass the name of the operation you wish to execute.
• fetchOptionsOverrides: Object - Specific overrides for this query. See MDN for info on what options can be passed

Guides

SSR

See graphql-hooks-ssr for an in depth guide.

Pagination

GraphQL Pagination can be implemented in various ways and it's down to the consumer to decide how to deal with the resulting data from paginated queries. Take the following query as an example of offset pagination:

export const allPostsQuery = `
  query allPosts($first: Int!, $skip: Int!) {
    allPosts(first: $first, skip: $skip) {
      id
      title
      url
    }
    _allPostsMeta {
      count
    }
  }
`;

In this query, the $first variable is used to limit the number of posts that are returned and the $skip variable is used to determine the offset at which to start. We can use these variables to break up large payloads into smaller chunks, or "pages". We could then choose to display these chunks as distinct pages to the user, or use an infinite loading approach and append each new chunk to the existing list of posts.

Separate pages

Here is an example where we display the paginated queries on separate pages:

import { React, useState } from 'react';
import { useQuery } from 'graphql-hooks';

export default function PostList() {
  // set a default offset of 0 to load the first page
  const [skipCount, setSkipCount] = useState(0);

  const { loading, error, data } = useQuery(allPostsQuery, {
    variables: { skip: skipCount, first: 10 }
  });

  if (error) return <div>There was an error!</div>;
  if (loading && !data) return <div>Loading</div>;

  const { allPosts, _allPostsMeta } = data;
  const areMorePosts = allPosts.length < _allPostsMeta.count;

  return (
    <section>
      <ul>
        {allPosts.map(post => (
          <li key={post.id}>
            <a href={post.url}>{post.title}</a>
          </li>
        ))}
      </ul>
      <button
        // reduce the offset by 10 to fetch the previous page
        onClick={() => setSkipCount(skipCount - 10)}
        disabled={skipCount === 0}
      >
        Previous page
      </button>
      <button
        // increase the offset by 10 to fetch the next page
        onClick={() => setSkipCount(skipCount + 10)}
        disabled={!areMorePosts}
      >
        Next page
      </button>
    </section>
  );
}

Infinite loading

Here is an example where we append each paginated query to the bottom of the current list:

import { React, useState } from 'react';
import { useQuery } from 'graphql-hooks';

// use options.updateData to append the new page of posts to our current list of posts
const updateData = (prevData, data) => ({
  ...data,
  allPosts: [...prevData.allPosts, ...data.allPosts]
});

export default function PostList() {
  const [skipCount, setSkipCount] = useState(0);

  const { loading, error, data } = useQuery(
    allPostsQuery,
    { variables: { skip: skipCount, first: 10 } },
    updateData
  );

  if (error) return <div>There was an error!</div>;
  if (loading && !data) return <div>Loading</div>;

  const { allPosts, _allPostsMeta } = data;
  const areMorePosts = allPosts.length < _allPostsMeta.count;

  return (
    <section>
      <ul>
        {allPosts.map(post => (
          <li key={post.id}>
            <a href={post.url}>{post.title}</a>
          </li>
        ))}
      </ul>
      {areMorePosts && (
        <button
          // set the offset to the current number of posts to fetch the next page
          onClick={() => setSkipCount(allPosts.length)}
        >
          Show more
        </button>
      )}
    </section>
  );
}

Authentication

Coming soon!

Fragments

Coming soon!

Migrating from Apollo

Coming soon!

Contributors

Thanks goes to these wonderful people (emoji key):

Brian Mullan
? ? ? ? ? ? ? ? ? ⚠️
Jack Clark
? ? ? ? ? ? ? ? ? ⚠️
Joe Warren
? ? ? ? ? ? ? ? ? ⚠️
Simone Busoli
? ? ?
jhey tompkins
⚠️ ? ? ? ?

This project follows the all-contributors specification. Contributions of any kind welcome!