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apollo-angular-link-http

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An Apollo Link to allow sending a single http request per operation.

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# HTTP Link [![npm version](https://badge.fury.io/js/apollo-angular-link-http.svg)](https://badge.fury.io/js/apollo-angular-link-http) [![Get on Slack](https://img.shields.io/badge/slack-join-orange.svg)](https://www.apollographql.com/slack) ## Purpose An Apollo Link to allow sending a single http request per operation. ## Installation `npm install apollo-angular-link-http --save` ## Usage ```ts import {HttpLinkModule, HttpLink} from 'apollo-angular-link-http'; @NgModule({ imports: [HttpLinkModule], }) class AppModule { constructor(httpLink: HttpLink) { const link = httpLink.create({uri: '/graphql'}); } } ``` ## HttpClient The HTTP Link relies on having `HttpClient` (from `@angular/common/http`) present in your application. ## Options HTTP Link takes an object with some options on it to customize the behavior of the link. If your server supports it, the HTTP link can also send over metadata about the request in the extensions field. To enable this, pass `includeExtensions` as true. If you would like to use persisted queries or just not to send a query, disable `includeQuery`. | name | value | default | required | | ----------------- | ----------------- | ---------- | -------- | | uri | string / function | `/graphql` | false | | includeExtensions | boolean | `false` | false | | includeQuery | boolean | `true` | false | | headers | HttpHeaders | `none` | false | | withCredentials | boolean | `none` | false | | method | string | `POST` | false | ## Context The HTTP Link uses the `headers` field on the context to allow passing headers to the HTTP request. It also supports the `withCredentials` field for defining credentials policy for request. These options will override the same key if passed when creating the the link. If some setting is different than the one in Options, this one will be used. | name | value | default | required | | ----------------- | ----------- | --------------- | -------- | | uri | string | `as in options` | false | | includeExtensions | boolean | `as in options` | false | | includeQuery | boolean | `as in options` | false | | headers | HttpHeaders | none | false | | withCredentials | boolean | `as in options` | false | | method | string | `as in options` | false | | useMultipart | boolean | `as in options` | false | ```js import {HttpLinkModule, HttpLink} from 'apollo-link-http'; import {ApolloModule, Apollo} from 'apollo-angular'; import {InMemoryCache} from 'apollo-cache-inmemory'; import {HttpClientModule} from '@angular/common/http'; @NgModules({ imports: [HttpClientModule, ApolloModule, HttpLinkModule], }) class AppModule { constructor(apollo: Apollo, httpLink: httpLink) { apollo.create({ link: httpLink.create({uri: '/graphql'}), cache: new InMemoryCache(), }); } } // a query with apollo-angular apollo.query({ query: MY_QUERY, context: { // example of setting the headers with context per operation headers: new HttpHeaders().set('X-Custom-Header', 'custom-value'), }, }); ``` ### Uri as function ```ts @NgModules({ imports: [HttpClientModule, ApolloModule, HttpLinkModule], }) class AppModule { constructor(apollo: Apollo, httpLink: httpLink) { apollo.create({ link: httpLink.create({ uri(operation) { return operation.operationName === 'login' ? '/auth' : '/graphq'; }, }), cache: new InMemoryCache(), }); } } ``` ### File upload In order to upload a file, you need to turn on `useMultipart` flag: ```ts apollo.query({ query: MY_QUERY, context: { useMultipart: true }, }); ``` ### Middleware ```ts import {ApolloLink} from 'apollo-link'; import {HttpLink} from 'apollo-angular-link-http'; class AppModule { constructor(httpLink: HttpLink) { const http = httpLink.create({uri: '/graphql'}); const middleware = new ApolloLink((operation, forward) => { operation.setContext({ headers: new HttpHeaders().set( 'Authorization', localStorage.getItem('token') || null, ), }); return forward(operation); }); const link = middleware.concat(http); } } ``` ### Afterware (error) ```js import {ApolloLink} from 'apollo-link'; import {HttpLink} from 'apollo-angular-link-http'; import {onError} from 'apollo-link-error'; import {Auth} from './auth.service'; class AppModule { constructor(httpLink: HttpLink, auth: Auth) { const http = httpLink.create({uri: '/graphql'}); const error = onError(({networkError}) => { if (networkError.status === 401) { auth.logout(); } }); const link = error.concat(http); } } ```