graphql-hooks

🎣 Minimal hooks-first GraphQL client.

Features

🥇 First-class hooks API
⚖️ Tiny bundle: only 7.6kB (2.8 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

yarn add graphql-hooks

Support

Node LTS
Browsers > 1%, not dead

Consider polyfilling:

FormData
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>
  )
}

Why `graphql-hooks`?

The first thing you may ask when seeing graphql-hooks is "Why not use Apollo hooks?". It's the comparison most will make. In fact, there's an article comparing the two over on LogRocket.

We believe graphql-hooks is a great choice as a hooks-first GraphQL client due to its concise API and package size.

In terms of performance, this is more of a grey area as we have no official benchmarks yet.

If you need a client that offers more customization such as advanced cache configuration, then apollo-hooks may work out to be a good choice for your project if bundle size is not an issue.

Pros	Cons
Small in size	Less "advanced" caching configuration
Concise API
Quick to get up and running

API
- GraphQLClient
- ClientContext
- useQuery
- useManualQuery
- useMutation
- useSubscription
Guides
- SSR
- Pagination
- File uploads
- HTTP Get Support
- Authentication
- Fragments
- Migrating from Apollo
  - ApolloClient ➡️ GraphQLClient
  - ApolloProvider ➡️ ClientContext.Provider
  - Query Component ➡️ useQuery
  - Mutation Component ➡️ useMutation
- Testing and mocking
- [Other]
  - Request interceptors

API

`GraphQLClient`

Usage:

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

config: Object containing configuration properties

url: The URL of your GraphQL HTTP server. If not specified, you must enable fullWsTransport and provide a valid subscriptionClient; otherwise is required.
fullWsTransport: Boolean - set to true if you want to use subscriptionClient to also send query and mutations via WebSocket; defaults to false
ssrMode: Boolean - set to true when using on the server for server-side rendering; defaults to false
useGETForQueries: Boolean - set to true to use HTTP GET method for all queries; defaults to false. See HTTP Get Support for more info
subscriptionClient: The WebSocket client configuration. Accepts either an instance of SubscriptionClient from subscriptions-transport-ws or Client from graphql-ws. A factory function is also accepted e.g. to avoid the creation of the client in SSR environments.
cache (Required if ssrMode is true, otherwise optional): 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. Check Request interceptors for more details how to manage fetch.
FormData: FormData implementation - defaults to the global FormData API. Polyfill this in a node.js environment. See file-uploads-nodejs for more info.
fetchOptions: See MDN for info on what options can be passed
headers: Object, e.g. { 'My-Header': 'hello' }
logErrors: Boolean - defaults to true
middleware: Accepts an array of middleware functions, default: none, see more in middlewares readme
onError({ operation, result }): Custom error handler
- operation: Object with query, variables and operationName
- result: Object containing data and error object that contains 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.removeHeader(key): Updates client.headers removing the header if it exists
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)
options.responseReducer: Reducer function to pick values from the original Fetch Response object. Values are merged to the request response under the data key. Example usage: {responseReducer: (data, response) => ({...data, myKey: response.headers.get('content-length)})

`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'

function App() {
  return (
    <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.
- persisted: Boolean - defaults to false; Pass true if your graphql server supports persisted flag to serve persisted queries.
- useCache: Boolean - defaults to true; cache the query result
- skip: Boolean - defaults to false; do not execute the query if set to true
- 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
- client: GraphQLClient - If a GraphQLClient is explicitly passed as an option, then it will be used instead of the client from the ClientContext.
- refetchAfterMutations: String | Object | (String | Object)[] - You can specify when a mutation should trigger query refetch.
  - If it's a string, it's the mutation string
  - If it's an object then it has properties mutation and filter
    - mutation: String - The mutation string
    - filter: Function (optional) - It receives mutation's variables as parameter and blocks refetch if it returns false
  - If it's an array, the elements can be of either type above

`useQuery` return value

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

loading: Boolean - true if the query is in flight
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
error: Object - Set if at least one of the following errors has occurred and contains:
- fetchError: Object - Set if an error occurred during the fetch call
- httpError: Object - Set if an error response was returned from the server
- graphQLErrors: Array - Populated if any errors occurred whilst resolving the query

`useManualQuery`

Use this when you don't want a query to automatically 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, resetFn] = 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
client: GraphQLClient - If a GraphQLClient is explicitly passed as an option, then it will be used instead of the client from the ClientContext.

In addition, there is an option to reset the current state before calling the mutation again, by calling resetFn(desiredState) where desiredState is optional and if passed, it will override the initial state with:

data: Object - the data
error: Error - the error
loading: Boolean - true if it is still loading
cacheHit: Boolean - true if the result was cached

`useSubscription`

To use subscription you can use either subscriptions-transport-ws or graphql-ws

API

useSubscription(operation, callback)

operation: Object - The GraphQL operation the following properties:
- query: String (required) - the GraphQL query
- variables: Object (optional) - Any variables the query might need
- operationName: String (optional) - If your query has multiple operations, you can choose which operation you want to call.
- client: GraphQLClient - If a GraphQLClient is explicitly passed as an option, then it will be used instead of the client from the ClientContext.
callback: Function - This will be invoked when the subscription receives an event from your GraphQL server - it will receive an object with the typical GraphQL response of { data: <your result>, errors?: [Error] }

Usage:

First follow the quick start guide to create the client and povider. Then we need to update the config for our GraphQLClient passing in the subscriptionClient:

import { GraphQLClient } from 'graphql-hooks'
import { SubscriptionClient } from 'subscriptions-transport-ws'
// or
import { createClient } from 'graphql-ws'

const client = new GraphQLClient({
  url: 'http://localhost:8000/graphql',
  subscriptionClient: () =>
    new SubscriptionClient('ws://localhost:8000/graphql', {
      /* additional config options */
    }),
  // or
  subscriptionClient: () =>
    createClient({
      url: 'ws://localhost:8000/graphql'
      /* additional config options */
    })
})

Next, within our React app, we can now make use of the useSubscription hook.

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

const TOTAL_COUNT_SUBSCRIPTION = `
  subscription TotalCount {
    totalCount {
      count
    }
  }
`

function TotalCountComponent() {
  const [count, setCount] = useState(0)
  const [error, setError] = useState(null)

  useSubscription({ query: TOTAL_COUNT_SUBSCRIPTION }, ({ data, errors }) => {
    if (errors && errors.length > 0) {
      // handle your errors
      setError(errors[0])
      return
    }

    // all good, handle the gql result
    setCount(data.totalCount.count)
  })

  if (error) {
    return <span>An error occurred {error.message}</span>
  }

  return <div>Current count: {count}</div>
}

Working Example:

See our subscription example which has both the client and server code to integrate subscriptions into your application.

See also the full WS transport example if you want to see how to send every operation through WebSocket.

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>
  )
}

Refetch queries with mutations subscription

We can have a query to automatically refetch when any mutation from a provided list execute. In the following example we are refetching a list of posts for a given user.

Example

export const allPostsByUserIdQuery = `
  query allPosts($userId: Int!) {
    allPosts(userId: $userId) {
      id
      title
      url
    }
  }
`

export const createPostMutation = `
  mutation createPost($userId: Int!, $text: String!) {
    createPost(userId: $userId, text: $text) {
      id
      title
      url
    }
  }
`

const myUserId = 5

useQuery(allPostsByUserIdQuery, {
  variables: {
    userId: myUserId
  },
  refetchAfterMutations: [
    {
      mutation: createPostMutation,
      filter: variables => variables.userId === myUserId
    }
  ]
})

File uploads

graphql-hooks complies with the GraphQL multipart request spec, allowing files to be used as query or mutation arguments. The same spec is also supported by popular GraphQL servers, including Apollo Server (see list of supported servers here).

If there are files to upload, the request's body will be a FormData instance conforming to the GraphQL multipart request spec.

import React, { useRef } from 'react'
import { useMutation } from 'graphql-hooks'

const uploadPostPictureMutation = `
  mutation UploadPostPicture($picture: Upload!) {
    uploadPostPicture(picture: $picture) {
      id
      pictureUrl
    }
  }
`

export default function PostForm() {
  // File input is always uncontrolled in React.
  // See: https://reactjs.org/docs/uncontrolled-components.html#the-file-input-tag.
  const fileInputRef = useRef(null)

  const [uploadPostPicture] = useMutation(uploadPostPictureMutation)

  const handleSubmit = event => {
    event.preventDefault()

    uploadPostPicture({
      variables: {
        picture: fileInputRef.current.files[0]
      }
    })
  }

  return (
    <form onSubmit={handleSubmit}>
      <input accept="image/*" ref={fileInputRef} type="file" />
      <button>Upload</button>
    </form>
  )
}

File uploads Node.js

import { FormData } from 'formdata-node'
import { fileFromPath } from 'formdata-node/file-from-path'

const client = new GraphQLClient({
  url: 'https://domain.com/graphql',
  fetch: require('node-fetch'),
  FormData
})

const uploadPostPictureMutation = `
  mutation UploadPostPicture($picture: Upload!) {
    uploadPostPicture(picture: $picture) {
      id
      pictureUrl
    }
  }
`

const { data, error } = await client.request({
  query: uploadPostPictureMutation,
  variables: { picture: await fileFromPath('some-file.txt') }
})

HTTP Get support

Using GET for queries can be useful, especially when implementing any sort of HTTP caching strategy. There are two ways you can do this:

Per Query

const { loading, error, data } = useQuery(MY_QUERY, {
  fetchOptionsOverrides: { method: 'GET' }
})

// same goes for useManualQuery
const [fetchSomething] = useManualQuery(MY_QUERY, {
  fetchOptionsOverrides: { method: 'GET' }
})

For All Queries

When you create your client, set the useGETForQueries option as true:

const client = new GraphQLClient({
  url: '/graphql',
  useGETForQueries: true
})

Authentication

You can have access the to the graphql-hooks client context by using the React's new context API. ClientContext is actually the result of React.createContext().

Login example

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

const LOGIN_MUTATION = `mutation LoginUser (name: String!, password: String!) {
  loginUser(name: $name, password: $password) {
    token
  }
}`

const Login = () => {
  const client = useContext(ClientContext)
  const [loginUserMutation] = useMutation(LOGIN_MUTATION)
  const [userName, setUserName] = useState()
  const [password, setPassword] = useState()

  const handleLogin = async e => {
    e.preventDefault()
    const { data, error } = await loginUserMutation({
      variables: { userName, password }
    })
    if (error) {
      // your code to handle login error
    } else {
      const { token } = data.loginUser
      client.setHeader('Authorization', `Bearer ${token}`)
      // your code to handle token in browser and login redirection
    }
  }
  return (
    <form onSubmit={handleLogin}>
      User Name:{' '}
      <input
        type={'text'}
        value={userName}
        onChange={e => setUserName(e.target.value)}
      />
      PassWord: <input
        type={'password'}
        value={password}
        onChange={e => setPassword(e.target.value)}
      />
      <input type={'submit'} value={'Login'} />
    </form>
  )
}

export default Login

In the above example we use useContext() hook to get access to the graphql-hooks clientContext. Then we request the token from the server by performing the loginUser mutation. In the case the login is success we set the token to the client's header (client.setHeader), otherwise we need to handle the error. For more information about graphql-hooks clientContext refer to GraphQLClient section.

Fragments

Coming soon!

Migrating from Apollo

For a real life example, compare the next.js with-apollo vs with-graphql-hooks. We have feature parity and the main-*.js bundle is a whopping 93% smaller (7.9KB vs 116KB).

ApolloClient ➡️ GraphQLClient

- import { ApolloClient } from 'apollo-client'
- import { InMemoryCache } from 'apollo-cache-inmemory'
+ import { GraphQLClient } from 'graphql-hooks'
+ import memCache from 'graphql-hooks-memcache'

- const client = new ApolloClient({
-  uri: '/graphql',
-  cache: new InMemoryCache()
- })
+ const client = new GraphQLClient({
+   url: '/graphql',
+   cache: memCache()
+ })

A lot of the options you'd pass to ApolloClient are the same as GraphQLClient:

uri ➡️ url
fetchOptions
onError - the function signature is slightly different
headers
fetch
cache

ApolloProvider ➡️ ClientContext.Provider

- import { ApolloProvider } from 'react-apollo'
+ import { ClientContext } from 'graphql-hooks'

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

Query Component ➡️ useQuery

- import { Query } from 'react-apollo'
- import gql from 'graphql-tag'
+ import { useQuery } from 'graphql-hooks'

function MyComponent() {
+ const { loading, error, data } = useQuery('...')

-  return (
-    <Query query={gql`...`}>
-     {({ loading, error, data}) => {
        if (loading) return 'Loading...'
        if (error) return 'Error :('

        return <div>{data}</div>
-      }}
-    </Query>
-  )
}

Query Component Props

A lot of options can be carried over as-is, or have direct replacements:

query ➡️ useQuery(query): Remove any usage of gql and pass your queries as strings.
variables ➡️ useQuery(query, { variables })
ssr ➡️ useQuery(query, { ssr })
Fetch Policies: See #75 for more info
- cache-first: This the default behaviour of graphql-hooks
- cache-and-network: The refetch function provides this behaviour it will set loading: true, but the old data will be still set until the fetch resolves.
- network-only ➡️ useQuery(QUERY, { skipCache: true })
- cache-only: Not supported
- no-cache ➡️ useQuery(QUERY, { useCache: false })

Not yet supported

errorPolicy: Any error will set the error to be truthy. See useQuery for more details.
pollInterval
notifyOnNetworkStatusChange
skip
onCompleted: Similar ability if using useManualQuery
onError: Similar ability if using useManualQuery
partialRefetch

Query Component Render Props

- <Query query={gql`...`}>
-  {(props) => {}}
- </Query>
+ const state = useQuery(`...`)

props.loading ➡️ const { loading } = useQuery('...')
props.error ➡️ const { error } = useQuery('...'): The error value from useQuery is Boolean the details of the error can be found in either:
- state.fetchError
- state.httpError
- state.graphQLErrors
props.refetch ️➡️ const { refetch } = useQuery('...')
props.updateData(prevResult, options) ️➡️ state.updateData(prevResult, newResult)

Not yet supported

props.networkStatus
props.startPolling
props.stopPolling
props.subscribeToMore

Mutation Component ➡️ useMutation

- import { Mutation } from 'react-apollo'
- import gql from 'graphql-tag'
+ import { useMutation } from 'graphql-hooks'

function MyComponent() {
+ const [mutateFn, { loading, error, data }] = useMutation('...')

-  return (
-    <Mutation mutation={gql`...`}>
-     {(mutateFn, { loading, error }) => {
        if (error) return 'Error :('

        return <button disabled={loading} onClick={() => mutateFn()}>Submit</button>
-      }}
-    </Mutation>
-  )
}

Mutation Props

mutation ➡️ useMutation(mutation) - no need to wrap it in gql
variables ➡️️ useMutation(mutation, { variables }) or mutateFn({ variables })
ignoreResults ➡️️️️ const [mutateFn] = useMutation(mutation)
onCompleted ➡️ ️mutateFn().then(onCompleted)
onError ➡️ mutateFn().then(({ error }) => {...})

Not yet supported

update: Coming soon #52
optimisticResponse
refetchQueries
awaitRefetchQueries
context

Mutation Component Render Props

- <Mutation mutation={gql`...`}>
-  {(mutateFn, props) => {}}
- </Mutation>
+ const [mutateFn, state] = useMutation(`...`)

props.data ➡️ const [mutateFn, { data }] = useMutation()
props.loading ➡️ const [mutateFn, { loading }] = useMutation()
props.error ➡️ const [mutateFn, { error }] = useMutation(): The the details of the error can be found in either:
- state.fetchError
- state.httpError
- state.graphQLErrors
client ️➡️️ const client = useContext(ClientContext) see ClientContext

Not yet supported

called

Testing and mocking

There is a LocalGraphQLClient class you can use to mock requests without a server for testing or development purposes.

This client inherits from GraphQLClient and provides the same API, but doesn't connect to any server and instead responds to pre-defined queries.

It needs to be supplied on creation with a localQueries object, which is an object of query functions.

const localQueries = {
  [allPostsQuery]: () => ({
    allPosts: [
      {
        id: 1,
        title: 'Test',
        url: 'https://example.com'
      }
    ]
  }),
  [createPostMutation]: () => ({ createPost: { id: 1 } })
}
const client = new LocalGraphQLClient({ localQueries })
const { data, error } = await client.request({
  query: 'allPostsQuery'
})

The LocalGraphQLClient will return data and error properties in the same format as the GraphQLClient

Variables

Variables can be used in the local mock queries given to the LocalGraphQLClient, which can then be supplied to the request function:

const localQueries = {
  AddNumbersQuery: ({ a, b }) => ({
    addedNumber: a + b
  })
}
const client = new LocalGraphQLClient({ localQueries })
const result = await client.request({
  query: 'AddNumbersQuery',
  variables: {
    a: 2,
    b: 3
  }
})
console.log(result.data.addedNumber) // Will be 5

Error mocking

Errors can be simply mocked in LocalGraphQLClient queries by using the LocalGraphQLError class:

const localQueries = {
  ErrorQuery: () =>
    new LocalGraphQLError({
      httpError: {
        status: 404,
        statusText: 'Not found',
        body: 'Not found'
      }
    })
}
const client = new LocalGraphQLClient({ localQueries })
const result = await client.request({
  query: 'ErrorQuery'
})
console.log(result.error) // The `error` object will have an `httpError`

Testing with React

Example tests that use the LocalGraphQLClient are provided in the examples/create-react-app/test folder.

The test-utils.js is a good example of how to create a custom render function using @testing-library/react which can wrap the render of a React component in a ClientContext setup to use the LocalGraphQLClient with supplied local queries:

const customRender = (ui, options) => {
  const client = new LocalGraphQLClient({
    localQueries: options.localQueries
  })

  const Wrapper = ({ children }) => {
    return (
      <ClientContext.Provider value={client}>{children}</ClientContext.Provider>
    )
  }

  Wrapper.propTypes = {
    children: T.node.isRequired
  }

  return render(ui, {
    wrapper: Wrapper,
    ...options
  })
}

export * from '@testing-library/react'

export { customRender as render }

Using this allows to easily render a component using the LocalGraphQLClient with local queries when writing tests:

// Comes from the above code
import { render, screen } from './test-utils'

const localQueries = {
  [allPostsQuery]: () => ({
    allPosts: [
      {
        id: 1,
        title: 'Test',
        url: 'https://example.com'
      }
    ]
  })
}

describe('Posts', () => {
  it('should render successfully', async () => {
    render(<Posts />, {
      localQueries
    })

    expect(
      await screen.findByRole('link', {
        name: /Test/i
      })
    ).toBeTruthy()
  })
})

Changing mock queries during tests

Because the LocalGraphQLClient just uses the localQueries object supplied to it, it is possible to modify or spy the local queries during tests. For example:

it('shows "No posts" if 0 posts are returned', async () => {
  jest.spyOn(localQueries, allPostsQuery).mockImplementation(() => ({
    allPosts: []
  }))

  render(<Posts />, {
    localQueries
  })

  expect(await screen.findByText('No posts')).toBeTruthy()
})

Other

Request interceptors

It is possible to provide a custom library to handle network requests. Having that there is more control on how to handle the requests. The following example shows how to supply axios HTTP client with interceptors. It can be handy in the situations where JWT token has expired, needs to be refreshed and request retried.

import axios from 'axios'
import { buildAxiosFetch } from '@lifeomic/axios-fetch'
import { GraphQLClient } from 'graphql-hooks'

const gqlAxios = axios.create()
gqlAxios.interceptors.response.use(
  function (response) {
    return response
  },
  function (error) {
    // Handle expired JWT and refresh token
  }
)

const client = new GraphQLClient({
  url: '/graphql',
  fetch: buildAxiosFetch(gqlAxios)
})

Community

We now use GitHub Discussions for our community. To join, click on "Discussions". We encourage you to start a new discussion, share some ideas or ask questions from the community. If you want to see the old community posts (on Spectrum) you can access them here.

Contributors

Thanks goes to these wonderful people (emoji key):

_{Brian Mullan} 💬 🐛 💻 🖋 📖 💡 🤔 🚧 👀 ⚠️	_{Jack Clark} 💬 🐛 💻 🖋 📖 💡 🤔 🚧 👀 ⚠️	_{Joe Warren} 💬 🐛 💻 🖋 📖 💡 🤔 🚧 👀 ⚠️	_{Simone Busoli} 💬 🐛 📖	_{jhey tompkins} ⚠️ 💬 🐛 💻 🖋 👀	_{Haroen Viaene} 🐛	_{Ari Bouius} 📖 🐛 💻 ⚠️
_{Klemen Kogovšek} 🐛 🤔 💻 ⚠️	_{Wésley Queiroz} 🐛 💻	_{Joseph Thomas} 🐛 💻 ⚠️	_{Edvinas Bartkus} 💻 💬 🐛 📖 💡 🤔 🚧 👀 ⚠️	_{Matías Olivera} 🐛 💻 ⚠️ 📖	_tcudok-jg 💻	_{Martin Adams} 📖
_{Gal Dubitski} 💻 🐛 📖 ⚠️	_{Abhishek Shende} 💻 🐛	_{fabienheureux} 👀	_{Hugh Boylan} 👀	_{Baqer Mamouri} 💻	_{Guillermo Gonzalez} 💻	_{Johan Brook} 💻 🐛 🚧
_{Peter Balazs} 💻 📖 💡 ⚠️	_{Mattia Panzeri} 💻 ⚠️	_{Alex Kondratyuk} 💻 ⚠️ 📖 🐛	_{Matias Cepeda} 📖	_{Jack Huey} 🐛 💻 📖 ⚠️