Apollo Federation Example

Start Federation using @graphql-tools/federation:

npm start

Then, visit http://localhost:4000 Service runs on http://localhost:4001 Service2 runs on http://localhost:4002

Run the following GQL query:

    query {
        someResolver {
            disappearingField {
                id
            }
        }
    }

If will fail with the following error even though the field disappearingField exists in the schema (here):

{
  "errors": [
    {
      "message": "Cannot query field \"disappearingField\" on type \"SomeTypeWithDisappearingField\".",
      "extensions": {
        "code": "GRAPHQL_VALIDATION_FAILED",
        "exception": {
          "stacktrace": [
            "GraphQLError: Cannot query field \"disappearingField\" on type \"SomeTypeWithDisappearingField\".",
            "    at Object.Field (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/graphql/validation/rules/FieldsOnCorrectTypeRule.js:51:13)",
            "    at Object.enter (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/graphql/language/visitor.js:301:32)",
            "    at Object.enter (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/graphql/utilities/TypeInfo.js:391:27)",
            "    at visit (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/graphql/language/visitor.js:197:21)",
            "    at validate (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/graphql/validation/validate.js:91:24)",
            "    at validate (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/apollo-server-core/dist/requestPipeline.js:188:39)",
            "    at processGraphQLRequest (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/apollo-server-core/dist/requestPipeline.js:99:38)",
            "    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)",
            "    at async processHTTPRequest (/Users/ori/WebstormProjects/apollo-federation/gateway/node_modules/apollo-server-core/dist/runHttpQuery.js:222:30)"
          ]
        }
      }
    }
  ]
}

Start Federation using ApolloGateway:

npm run start:apollo

Run the same query above. It will work and return the following:

{
  "data": {
    "someResolver": null
  }
}