@fabienjuif/graph-client

light zero dependency graphql-client, supporting cache and SSR

Features

Light (bundlesize)
Supports browser and Node (SSR compatible)
Supports cache (via third party library, or your own code)
- cache is not used for mutations
- cache can be disabled per request with noCache: true option

Install

npm install --save @fabienjuif/graph-client

API

import createClient from '@fabienjuif/graph-client'

createClient(options: object): Client: creates and returns a new graphql client
- options.url: (required), the graphql endpoint to query
- options.cache: (optional, default = undefined), the cache implementation to use, it must implement set(key: string, value: object) and get(key: string): object to be compatible. You can use a Map or lru package for example.
- options.token: (optional, default = undefined) will be used to add an authorization header, can be:
  - a ̀string: in which cache it will the client will add Bearer in front of it
  - a function:
    - if the function returns a Promise, the client will wait the promise to resolve, then add Bearer before the returned value. Attention, your query will not be send to your graphql API until the promise is resolved!
    - in other cases, the Bearer is added to the returned value
- options.logger: (optional, default = console), the logger to user, it can implement logger.trace(value: any) or logger('trace', value: any) and will be used to log errors if found
- options.headers: (optional; default = {}), the headers to set to http requests

const graphql = createClient(**options**)

graphql.setHeaders(param: function|object):
- if param is a function it will be called with the previous headers and the returned value will be used as new headers
- in other cases param will be used as new headers
graphql(query: string, variables: object, options: object): Promise: will query your endpoint and returns the data part
- if cache is set it will be used, and if an entry is found it will be returned without calling the API
- if the query is a mutation, the cache will not be used
- if options.noCache is set to true the cache, even if it exists, will not be used

Usage / Examples

Minimum

This is minimal informations you have to give to use this lib. In this case, the client does not use cache.

import createClient from '@fabienjuif/graph-client'

const graphql = createClient({
  url: 'https://my-domain/graphql',
})

const QUERY = `
query GetUser($id: String!) {
  user (id: $id) {
    id
    name
    email
  }
}
`

graphql(QUERY, { id: '2' })
  .then(data => console.log(data))

LRU cache

In this example, the client will use a cache from an external library (here lru).

import LRU from 'lru'
import createClient from '@fabienjuif/graph-client'

const graphql = createClient({
  url: 'http://my-domain.com/graphql'
  cache: new LRU(100), // max 100 items
})

const QUERY = `
query getUser($id: String!) {
  user(id: $id) {
    id
    name
    email
  }
}
`
const run = async () => {
  // first call will set the result into the cache
  // the cache key is a composition of your query and variables
  // both should be serializable
  const { user } = await graphql(QUERY, { id: '2' })
  console.log(user)

  // second call will use cache instead of quering the database
  const { user: user2 } = await graphql(QUERY, { id: '2' })
  console.log(user2)

  // third call will call your endpoint because variables are differents
  // a new entry will be added to the cache
  const { user: user3 } = await graphql(QUERY, { id: '3' })
  console.log(user3)
}
run()

Map cache

In this example, the client will use a javascript Map as a cache.

import createClient from '@fabienjuif/graph-client'

const graphql = createClient({
  url: 'http://my-domain.com/graphql'
  cache: new Map(),
})

const QUERY = `
query getUser($id: String!) {
  user(id: $id) {
    id
    name
    email
  }
}
`
const run = async () => {
  // first call will set the result into the cache
  // the cache key is a composition of your query and variables
  // both should be serializable
  const { user } = await graphql(QUERY, { id: '2' })
  console.log(user)

  // second call will use cache instead of quering the database
  const { user: user2 } = await graphql(QUERY, { id: '2' })
  console.log(user2)

  // third call will call your endpoint because variables are differents
  // a new entry will be added to the cache
  const { user: user3 } = await graphql(QUERY, { id: '3' })
  console.log(user3)
}
run()

Disable cache for specific queries

In this example cache is set from a javascript Map. The cache will not be used for one of the request, even if the cache is set and the query is a graphql query (not a mutation).

import createClient from '@fabienjuif/graph-client'

const graphql = createClient({
  url: 'https://my-domain/graphql',
  cache: new Map(), // use a Javascript map as cache
})

const CACHED_QUERY = `
query GetUser($id: String!) {
  user (id: $id) {
    id
    name
    email
  }
}
`

// this request will be cached
graphql(CACHED_QUERY, { id: '2' })
  .then(data => console.log(data))

const QUERY = `
query GetTopics($max: Int!) {
  topics (max: $max) {
    id
    title
  }
}
`

// this request will NOT be cached because we ask not to use it in request scope
// even if the cache is specified in the factory
graphql(QUERY, { max: 10 }, { noCache: true })
  .then(data => console.log(data))

Set a token

In this example the token is retrieved from the localStorage for each request. If the token does not exists then the Authorization header will not be set

import createClient from '@fabienjuif/graph-client'

const getToken = () => localStorage.getItem('token')

const graphql = createClient({
  url: 'https://my-domain/graphql',
  token: getToken, // token can also be a string, or a function that returns a promise
})

const run = async () => {
  // set a token
  localStorage.setItem('token', 'my-token')

  // first call the Authorization header is set:
  //  - Authorization: Bearer my-token
  const { user } = await graphql(QUERY, { id: '2' })
  console.log(user)

  // remove the token
  localStorage.removeItem('token')

  // second call the Authorization header is not set
  const { user: user2 } = await graphql(QUERY, { id: '2' })
  console.log(user2)
}
run()

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