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Using Apollo schema stitching with context and error handling
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| const { HttpLink } = require("apollo-link-http"); | |
| const { ApolloLink } = require("apollo-link"); | |
| const { setContext } = require("apollo-link-context"); | |
| const { onError } = require("apollo-link-error"); | |
| const fetch = require("node-fetch"); | |
| const express = require("express"); | |
| const { introspectSchema, makeRemoteExecutableSchema, ApolloServer, gql, mergeSchemas } = require("apollo-server-express"); | |
| const { TypeInfo, GraphQLSchema } = require("graphql"); | |
| const assert = require("assert"); | |
| const lodash = require("lodash"); | |
| const http = require("http"); | |
| const links = [ | |
| { | |
| path : "http://someserver/" | |
| }, | |
| { | |
| path : "http://anotherserver/" | |
| } | |
| ]; | |
| const schemas = []; | |
| for(let link of links) { | |
| // foreach link create an httplink | |
| let remoteLink = new HttpLink({ uri : link.path, fetch }); | |
| let remoteContext = setContext((req, previous) => { | |
| // if the authorization token doesn't exist, or is malformed, do not pass it upstream | |
| if ( | |
| !previous.graphqlContext.authorization | |
| || | |
| !previous.graphqlContext.authorization.match(/^Bearer /) | |
| ) { | |
| return; | |
| } | |
| return { | |
| headers: { | |
| 'Authorization': previous.graphqlContext.authorization, | |
| } | |
| } | |
| }); | |
| let remoteError = onError(({ networkError, graphQLErrors }) => { | |
| if (graphQLErrors) { | |
| graphQLErrors.forEach((val) => { | |
| Object.setPrototypeOf(val, Error.prototype); | |
| }); | |
| } | |
| }); | |
| let remoteSchema = await introspectSchema(remoteLink); | |
| let remoteExecutableSchema = makeRemoteExecutableSchema({ | |
| schema : remoteSchema, | |
| link : ApolloLink.from([ | |
| remoteContext, | |
| remoteError, | |
| remoteLink | |
| ]) | |
| }); | |
| schemas.push(remoteExecutableSchema); | |
| } | |
| var schema = mergeSchemas({ | |
| schemas : schemas | |
| }); | |
| const server = new ApolloServer({ | |
| schema, | |
| context : ({ req }) => { | |
| return { | |
| authorization : req.headers.authorization | |
| } | |
| } | |
| }); |
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