HttpLink
Get GraphQL results over a network using HTTP fetch.
HttpLink is a terminating link that sends a GraphQL operation to a remote endpoint over HTTP. It combines the functionality of BaseHttpLink and ClientAwarenessLink into a single link.
HttpLink supports both POST and GET requests, and you can configure HTTP options on a per-operation basis. You can use these options for authentication, persisted queries, dynamic URIs, and other granular updates.
1 import { HttpLink } from "@apollo/client"; 2 3 const link = new HttpLink({ 4 uri: "http://localhost:4000/graphql", 5 // Additional options 6 });Constructor signature
1constructor( 2 options: HttpLink.Options = {} 3): HttpLinkOperation results
After your GraphQL endpoint successfully responds with the result of an operation, HttpLink sets the Response object as the response field of the operation context. This enables each previous link in your link chain to interact with the response.
Customizing fetch
Provide a custom fetch option to the HttpLink constructor if you need fine-grained control over the underlying fetch call. The function should behave identically to the Fetch API.
Types
Options provided to the HttpLink constructor.
ClientAwarenessLink.ClientAwarenessOptionsConfigures the "client awareness" feature. This feature allows you to identify distinct applications in Apollo Studio and Apollo Server logs (and other monitoring or analytics tools) by adding information about the your application to outgoing requests.
RequestCredentialsThe credentials policy to use for each fetch call.
ClientAwarenessLink.EnhancedClientAwarenessOptionsConfigures the "enhanced client awareness" feature. This feature allows you to identify the version of the Apollo Client library used in your application in Apollo Studio (and other monitoring or analytics tools) by adding information about the Apollo Client library to outgoing requests.
typeof fetchA function to use instead of calling the Fetch API directly when sending HTTP requests to your GraphQL endpoint. The function must conform to the signature of fetch.
By default, the Fetch API is used unless it isn't available in your runtime environment.
See Customizing fetch.
RequestInitAny overrides of the fetch options argument to pass to the fetch call.
An object containing options to use for each call to fetch. If a particular option is not included in this object, the default value of that option is used.
Record<string, string>An object representing headers to include in every HTTP request.
1 { 2 "Authorization": "Bearer 1234" 3 }booleanIf true, includes the extensions field in operations sent to your GraphQL endpoint.
If true, unused variables from the operation will not be stripped from the request and will instead be sent to the GraphQL endpoint.
Read more...
Unused variables are likely to trigger server-side validation errors, per https://spec.graphql.org/draft/#sec-All-Variables-Used. includeUnusedVariables can be useful if your server deviates from the GraphQL specification by not strictly enforcing that rule.
booleanIf true, header names won't be automatically normalized to lowercase. This allows for non-http-spec-compliant servers that might expect capitalized header names.
BaseHttpLink.PrinterA function to use when transforming a GraphQL document into a string. It accepts an ASTNode (typically a DocumentNode) and the original print function as arguments, and is expected to return a string. This option enables you to, for example, use stripIgnoredCharacters to remove whitespace from queries.
By default the GraphQL print function is used.
1 import { stripIgnoredCharacters } from "graphql"; 2 3 const httpLink = new HttpLink({ 4 uri: "/graphql", 5 print: (ast, originalPrint) => stripIgnoredCharacters(originalPrint(ast)), 6 });string | BaseHttpLink.UriFunctionThe URL of the GraphQL endpoint to send requests to. Can also be a function that accepts an ApolloLink.Operation object and returns the string URL to use for that operation.
booleanIf true, the link uses an HTTP GET request when sending query operations to your GraphQL endpoint. Mutation operations continue to use POST requests. If you want all operations to use GET requests, set fetchOptions.method instead.
Options passed to HttpLink through request context. Previous non-terminating links in the link chain also can set these values to customize the behavior of HttpLink for each operation.
HttpLink constructor. If a value is provided to both, the value in context takes precedence.ClientAwarenessLink.ClientAwarenessOptionsConfigures the "client awareness" feature. This feature allows you to identify distinct applications in Apollo Studio and Apollo Server logs (and other monitoring or analytics tools) by adding information about the your application to outgoing requests.
RequestCredentialsThe credentials policy to use for each fetch call.
RequestInitAny overrides of the fetch options argument to pass to the fetch call.
An object containing options to use for each call to fetch. If a particular option is not included in this object, the default value of that option is used.
Record<string, string>An object representing headers to include in every HTTP request.
1 { 2 "Authorization": "Bearer 1234" 3 }BaseHttpLink.HttpOptionsAn object that configures advanced functionality, such as support for persisted queries.
string | BaseHttpLink.UriFunctionThe URL of the GraphQL endpoint to send requests to. Can also be a function that accepts an ApolloLink.Operation object and returns the string URL to use for that operation.