Make the schema into a subgraph

index.js

@@ -1,9 +1,12 @@
-import {ApolloServer} from 'apollo-server';
+import {ApolloServer, gql} from 'apollo-server';
-import {resolvers, typeDefs} from './schema.js';
+import {buildSubgraphSchema} from '@apollo/subgraph';
+import {readFileSync} from 'fs';
+import {resolvers} from './resolvers.js';
+
+const typeDefs = gql(readFileSync('./schema.graphql', 'utf-8'));
 
 const server = new ApolloServer({
-  typeDefs,
+  schema: buildSubgraphSchema({typeDefs, resolvers}),
-  resolvers,
   introspection: true,
   playground: true
 });

package-lock.json

@@ -5,9 +5,10 @@
   "packages": {
     "": {
       "dependencies": {
+        "@apollo/subgraph": "^0.3.1",
         "apollo-server": "^2.25.3",
         "countries-list": "^2.5.4",
-        "graphql": "^14.6.0",
+        "graphql": "^15.8.0",
         "provinces": "^1.11.0",
         "sift": "^12.0.0"
       },
@@ -47,6 +48,17 @@
       "resolved": "https://registry.npmjs.org/@types/node/-/node-10.17.60.tgz",
       "integrity": "sha512-F0KIgDJfy2nA3zMLmWGKxcH2ZVEtCZXHHdOQs2gSaQ27+lNeEfGxzkIw90aXswATX7AZ33tahPbzy6KAfUreVw=="
     },
+    "node_modules/@apollo/subgraph": {
+      "version": "0.3.1",
+      "resolved": "https://registry.npmjs.org/@apollo/subgraph/-/subgraph-0.3.1.tgz",
+      "integrity": "sha512-MWqzfZEcvN86iwwgsgkFnkoBvv/wCdw/qyXjayuZ4wwQgVZ8NpFNbUxjRC0MwKNHwBU/ZH1oDHOnC8WbUuUMsg==",
+      "engines": {
+        "node": ">=12.13.0 <17.0"
+      },
+      "peerDependencies": {
+        "graphql": "^15.8.0 || ^16.0.0"
+      }
+    },
     "node_modules/@apollographql/apollo-tools": {
       "version": "0.5.2",
       "resolved": "https://registry.npmjs.org/@apollographql/apollo-tools/-/apollo-tools-0.5.2.tgz",
@@ -2901,14 +2913,11 @@
       }
     },
     "node_modules/graphql": {
-      "version": "14.6.0",
+      "version": "15.8.0",
-      "resolved": "https://registry.npmjs.org/graphql/-/graphql-14.6.0.tgz",
+      "resolved": "https://registry.npmjs.org/graphql/-/graphql-15.8.0.tgz",
-      "integrity": "sha512-VKzfvHEKybTKjQVpTFrA5yUq2S9ihcZvfJAtsDBBCuV6wauPu1xl/f9ehgVf0FcEJJs4vz6ysb/ZMkGigQZseg==",
+      "integrity": "sha512-5gghUc24tP9HRznNpV2+FIoq3xKkj5dTQqf4v0CpdPbFVwFkWoxOM+o+2OC9ZSvjEMTjfmG9QT+gcvggTwW1zw==",
-      "dependencies": {
-        "iterall": "^1.2.2"
-      },
       "engines": {
-        "node": ">= 6.x"
+        "node": ">= 10.x"
       }
     },
     "node_modules/graphql-extensions": {
@@ -5571,6 +5580,12 @@
         }
       }
     },
+    "@apollo/subgraph": {
+      "version": "0.3.1",
+      "resolved": "https://registry.npmjs.org/@apollo/subgraph/-/subgraph-0.3.1.tgz",
+      "integrity": "sha512-MWqzfZEcvN86iwwgsgkFnkoBvv/wCdw/qyXjayuZ4wwQgVZ8NpFNbUxjRC0MwKNHwBU/ZH1oDHOnC8WbUuUMsg==",
+      "requires": {}
+    },
     "@apollographql/apollo-tools": {
       "version": "0.5.2",
       "resolved": "https://registry.npmjs.org/@apollographql/apollo-tools/-/apollo-tools-0.5.2.tgz",
@@ -7882,12 +7897,9 @@
       "dev": true
     },
     "graphql": {
-      "version": "14.6.0",
+      "version": "15.8.0",
-      "resolved": "https://registry.npmjs.org/graphql/-/graphql-14.6.0.tgz",
+      "resolved": "https://registry.npmjs.org/graphql/-/graphql-15.8.0.tgz",
-      "integrity": "sha512-VKzfvHEKybTKjQVpTFrA5yUq2S9ihcZvfJAtsDBBCuV6wauPu1xl/f9ehgVf0FcEJJs4vz6ysb/ZMkGigQZseg==",
+      "integrity": "sha512-5gghUc24tP9HRznNpV2+FIoq3xKkj5dTQqf4v0CpdPbFVwFkWoxOM+o+2OC9ZSvjEMTjfmG9QT+gcvggTwW1zw=="
-      "requires": {
-        "iterall": "^1.2.2"
-      }
     },
     "graphql-extensions": {
       "version": "0.15.0",

package.json

@@ -9,9 +9,10 @@
     "extends": "@trevorblades"
   },
   "dependencies": {
+    "@apollo/subgraph": "^0.3.1",
     "apollo-server": "^2.25.3",
     "countries-list": "^2.5.4",
-    "graphql": "^14.6.0",
+    "graphql": "^15.8.0",
     "provinces": "^1.11.0",
     "sift": "^12.0.0"
   },

resolvers.js

@@ -1,74 +1,6 @@
 import countriesList from 'countries-list';
 import provinces from 'provinces';
 import sift from 'sift';
-import {gql} from 'apollo-server';
-
-export const typeDefs = gql`
-  type Continent {
-    code: ID!
-    name: String!
-    countries: [Country!]!
-  }
-
-  type Country {
-    code: ID!
-    name: String!
-    native: String!
-    phone: String!
-    continent: Continent!
-    capital: String
-    currency: String
-    languages: [Language!]!
-    emoji: String!
-    emojiU: String!
-    states: [State!]!
-  }
-
-  type State {
-    code: String
-    name: String!
-    country: Country!
-  }
-
-  type Language {
-    code: ID!
-    name: String
-    native: String
-    rtl: Boolean!
-  }
-
-  input StringQueryOperatorInput {
-    eq: String
-    ne: String
-    in: [String]
-    nin: [String]
-    regex: String
-    glob: String
-  }
-
-  input CountryFilterInput {
-    code: StringQueryOperatorInput
-    currency: StringQueryOperatorInput
-    continent: StringQueryOperatorInput
-  }
-
-  input ContinentFilterInput {
-    code: StringQueryOperatorInput
-  }
-
-  input LanguageFilterInput {
-    code: StringQueryOperatorInput
-  }
-
-  type Query {
-    continents(filter: ContinentFilterInput): [Continent!]!
-    continent(code: ID!): Continent
-    countries(filter: CountryFilterInput): [Country!]!
-    country(code: ID!): Country
-    languages(filter: LanguageFilterInput): [Language!]!
-    language(code: ID!): Language
-  }
-`;
 
 function filterToSift(filter = {}) {
   return sift(
@@ -111,7 +43,8 @@ export const resolvers = {
         };
       }),
     states: country =>
-      provinces.filter(province => province.country === country.code)
+      provinces.filter(province => province.country === country.code),
+    __resolveReference: country => countries[country.code]
   },
   State: {
     code: state => state.short,
@@ -124,10 +57,12 @@ export const resolvers = {
         .map(([code, country]) => ({
           ...country,
           code
-        }))
+        })),
+    __resolveReference: continent => continents[continent.code]
   },
   Language: {
-    rtl: language => Boolean(language.rtl)
+    rtl: language => Boolean(language.rtl),
+    __resolveReference: language => languages[language.code]
   },
   Query: {
     continent(parent, {code}) {

schema.graphql

@@ -0,0 +1,64 @@
+type Continent @key(fields: "code") {
+  code: ID!
+  name: String!
+  countries: [Country!]!
+}
+
+type Country @key(fields: "code") {
+  code: ID!
+  name: String!
+  native: String!
+  phone: String!
+  continent: Continent!
+  capital: String
+  currency: String
+  languages: [Language!]!
+  emoji: String!
+  emojiU: String!
+  states: [State!]!
+}
+
+type State {
+  code: String
+  name: String!
+  country: Country!
+}
+
+type Language @key(fields: "code") {
+  code: ID!
+  name: String
+  native: String
+  rtl: Boolean!
+}
+
+input StringQueryOperatorInput {
+  eq: String
+  ne: String
+  in: [String]
+  nin: [String]
+  regex: String
+  glob: String
+}
+
+input CountryFilterInput {
+  code: StringQueryOperatorInput
+  currency: StringQueryOperatorInput
+  continent: StringQueryOperatorInput
+}
+
+input ContinentFilterInput {
+  code: StringQueryOperatorInput
+}
+
+input LanguageFilterInput {
+  code: StringQueryOperatorInput
+}
+
+type Query {
+  continents(filter: ContinentFilterInput): [Continent!]!
+  continent(code: ID!): Continent
+  countries(filter: CountryFilterInput): [Country!]!
+  country(code: ID!): Country
+  languages(filter: LanguageFilterInput): [Language!]!
+  language(code: ID!): Language
+}