Add union type

doc/example_queries/09_union.graphql

@@ -0,0 +1,16 @@
+{
+  allMachines {
+    machines {
+      ... on Vehicle {
+        id,
+        name,
+        vehicleClass
+      },
+      ... on Starship {
+        id,
+        name,
+        starshipClass
+      }
+    }
+  }
+}

src/schema/__tests__/machine.js

@@ -0,0 +1,178 @@
+/**
+ *  Copyright (c) 2015, Facebook, Inc.
+ *  All rights reserved.
+ *
+ * This source code is licensed under the license found in the
+ * LICENSE-examples file in the root directory of this source tree.
+ */
+
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+import { swapi } from './swapi';
+
+// 80+ char lines are useful in describe/it, so ignore in this file.
+/* eslint-disable max-len */
+
+function getDocument(query) {
+  return `${query}
+    fragment AllStarshipProperties on Starship {
+      MGLT
+      starshipCargoCapacity: cargoCapacity
+      consumables
+      starshipCostInCredits: costInCredits
+      crew
+      hyperdriveRating
+      length
+      manufacturers
+      maxAtmospheringSpeed
+      model
+      name
+      passengers
+      starshipClass
+      filmConnection(first:1) { edges { node { title } } }
+      pilotConnection(first:1) { edges { node { name } } }
+    }
+
+    fragment AllVehicleProperties on Vehicle {
+      vehicleCargoCapacity: cargoCapacity
+      consumables
+      vehicleCostInCredits: costInCredits
+      crew
+      length
+      manufacturers
+      maxAtmospheringSpeed
+      model
+      name
+      passengers
+      vehicleClass
+      filmConnection(first:1) { edges { node { title } } }
+      pilotConnection(first:1) { edges { node { name } } }
+    }
+
+    fragment AllPersonProperties on Person {
+      birthYear
+      eyeColor
+      gender
+      hairColor
+      height
+      homeworld { name }
+      mass
+      name
+      skinColor
+      species { name }
+      filmConnection(first:1) { edges { node { title } } }
+      starshipConnection(first:1) { edges { node { name } } }
+      vehicleConnection(first:1) { edges { node { name } } }
+    }
+  `;
+}
+
+describe('Machine type', async () => {
+  it('Gets an object by global ID', async () => {
+    const query = '{ starship(starshipID: 5) { id, name } }';
+    const result = await swapi(query);
+    const nextQuery = `
+      { 
+        machine(id: "${result.data.starship.id}") { 
+          ... on Vehicle { id, name }, 
+          ... on Starship { id, name },
+          ... on Person { id, name }
+        }
+      }
+    `;
+    const nextResult = await swapi(nextQuery);
+    expect(result.data.starship.name).to.equal('Sentinel-class landing craft');
+    expect(nextResult.data.machine.name).to.equal(
+      'Sentinel-class landing craft',
+    );
+    expect(result.data.starship.id).to.equal(nextResult.data.machine.id);
+  });
+
+  it('Gets all properties', async () => {
+    const query = '{ starship(starshipID: 5) { id, name } }';
+    const idResult = await swapi(query);
+
+    const nextQuery = getDocument(
+      `{
+      machine(id: "${idResult.data.starship.id}") {
+        ... on Starship {
+          ...AllStarshipProperties
+        }
+        ... on Vehicle {
+          ...AllVehicleProperties
+        }
+        ... on Person {
+          ...AllPersonProperties
+        }
+      }
+    }`,
+    );
+    const result = await swapi(nextQuery);
+    const expected = {
+      MGLT: 70,
+      starshipCargoCapacity: 180000,
+      consumables: '1 month',
+      starshipCostInCredits: 240000,
+      crew: '5',
+      filmConnection: { edges: [{ node: { title: 'A New Hope' } }] },
+      hyperdriveRating: 1,
+      length: 38,
+      manufacturers: ['Sienar Fleet Systems', 'Cyngus Spaceworks'],
+      maxAtmospheringSpeed: 1000,
+      model: 'Sentinel-class landing craft',
+      name: 'Sentinel-class landing craft',
+      passengers: '75',
+      pilotConnection: { edges: [] },
+      starshipClass: 'landing craft',
+    };
+    expect(result.data.machine).to.deep.equal(expected);
+  });
+
+  it('All objects query', async () => {
+    const query = getDocument(
+      `{ 
+        allMachines { 
+          edges { 
+            cursor, 
+              node { 
+                ... on Starship { ...AllStarshipProperties }, 
+                ... on Vehicle { ...AllVehicleProperties },
+                ... on Person { ... AllPersonProperties }
+              } 
+            } 
+          } 
+        }`,
+    );
+    const result = await swapi(query);
+    expect(result.data.allMachines.edges.length).to.equal(81);
+  });
+
+  it('Pagination query', async () => {
+    const query = `{
+      allMachines(first: 2) {
+        edges {
+          cursor, 
+          node { 
+            ... on Vehicle { name }, 
+            ... on Starship { name },
+            ... on Person { name }
+          } 
+        } 
+      }
+    }`;
+    const result = await swapi(query);
+    expect(result.data.allMachines.edges.map(e => e.node.name)).to.deep.equal([
+      'Sand Crawler',
+      'T-16 skyhopper',
+    ]);
+    const nextCursor = result.data.allMachines.edges[1].cursor;
+
+    const nextQuery = `{ allMachines(first: 2, after:"${nextCursor}") {
+      edges { cursor, node { ... on Vehicle { name }, ... on Starship { name }, ... on Person { name } } } }
+    }`;
+    const nextResult = await swapi(nextQuery);
+    expect(
+      nextResult.data.allMachines.edges.map(e => e.node.name),
+    ).to.deep.equal(['X-34 landspeeder', 'TIE/LN starfighter']);
+  });
+});

src/schema/apiHelper.js

@@ -32,6 +32,14 @@ export async function getObjectFromUrl(url: string): Promise<Object> {
   return objectWithId(data);
 }
 
+/**
+ * Given an object URL, return the Swapi type from it
+ * @param url
+ */
+export function getSwapiTypeFromUrl(url: string): string {
+  return url.split('/')[4];
+}
+
 /**
  * Given a type and ID, get the object with the ID.
  */

src/schema/graphQLFilteredUnionType.js

@@ -0,0 +1,26 @@
+/**
+ *  Copyright (c) 2015, Facebook, Inc.
+ *  All rights reserved.
+ *
+ * This source code is licensed under the license found in the
+ * LICENSE-examples file in the root directory of this source tree.
+ */
+
+import { GraphQLUnionType } from 'graphql';
+import { GraphQLUnionTypeConfig } from 'graphql/type/definition';
+
+/**
+ * GraphQLUnionType with a 'filter' method that allow to filter the
+ * elements of the union
+ */
+export default class GraphQLFilteredUnionType extends GraphQLUnionType {
+  constructor(config: GraphQLUnionTypeConfig<*, *>): void {
+    super(config);
+
+    if ('filter' in config) {
+      this.filter = config.filter;
+    } else {
+      this.filter = (type, objects) => objects;
+    }
+  }
+}

src/schema/index.js

@@ -13,6 +13,7 @@ import {
   GraphQLInt,
   GraphQLList,
   GraphQLObjectType,
+  GraphQLUnionType,
   GraphQLSchema,
 } from 'graphql';
 
@@ -25,26 +26,37 @@ import {
 
 import { getObjectsByType, getObjectFromTypeAndId } from './apiHelper';
 
-import { swapiTypeToGraphQLType, nodeField } from './relayNode';
+import {
+  swapiTypeToGraphQLType,
+  graphQLTypeToSwapiType,
+  nodeField,
+} from './relayNode';
+import GraphQLFilteredUnionType from './graphQLFilteredUnionType';
 
 /**
  * Creates a root field to get an object of a given type.
  * Accepts either `id`, the globally unique ID used in GraphQL,
- * or `idName`, the per-type ID used in SWAPI.
+ * or `idName`, the per-type ID used in SWAPI (idName is only
+ * usable on non-union elements).
  */
 function rootFieldByID(idName, swapiType) {
-  const getter = id => getObjectFromTypeAndId(swapiType, id);
+  const graphQLType = swapiTypeToGraphQLType(swapiType);
   const argDefs = {};
   argDefs.id = { type: GraphQLID };
-  argDefs[idName] = { type: GraphQLID };
+  if (!(graphQLType instanceof GraphQLUnionType)) {
+    argDefs[idName] = { type: GraphQLID };
+  }
   return {
-    type: swapiTypeToGraphQLType(swapiType),
+    type: graphQLType,
     args: argDefs,
     resolve: (_, args) => {
-      if (args[idName] !== undefined && args[idName] !== null) {
-        return getter(args[idName]);
+      if (
+        !(swapiType instanceof GraphQLUnionType) &&
+        args[idName] !== undefined &&
+        args[idName] !== null
+      ) {
+        return getObjectFromTypeAndId(swapiType, args[idName]);
       }
-
       if (args.id !== undefined && args.id !== null) {
         const globalId = fromGlobalId(args.id);
         if (
@@ -54,7 +66,7 @@ function rootFieldByID(idName, swapiType) {
         ) {
           throw new Error('No valid ID extracted from ' + args.id);
         }
-        return getter(globalId.id);
+        return getObjectFromTypeAndId(globalId.type, globalId.id);
       }
       throw new Error('must provide id or ' + idName);
     },
@@ -95,7 +107,31 @@ full "{ edges { node } }" version should be used instead.`,
     type: connectionType,
     args: connectionArgs,
     resolve: async (_, args) => {
-      const { objects, totalCount } = await getObjectsByType(swapiType);
+      const graphQLType = swapiTypeToGraphQLType(swapiType);
+      let objects = [];
+      let totalCount = 0;
+      if (graphQLType instanceof GraphQLUnionType) {
+        for (const type of graphQLType.getTypes()) {
+          // eslint-disable-next-line no-await-in-loop
+          const objectsByType = await getObjectsByType(
+            graphQLTypeToSwapiType(type),
+          );
+          if (graphQLType instanceof GraphQLFilteredUnionType) {
+            objectsByType.objects = graphQLType.filter(
+              type,
+              objectsByType.objects,
+            );
+            objectsByType.totalCount = objectsByType.objects.length;
+          }
+          objects = objects.concat(objectsByType.objects);
+          totalCount += objectsByType.totalCount;
+        }
+      } else {
+        const objectsByType = await getObjectsByType(swapiType);
+        objects = objects.concat(objectsByType.objects);
+        totalCount = objectsByType.totalCount;
+      }
+
       return {
         ...connectionFromArray(objects, args),
         totalCount,
@@ -122,6 +158,8 @@ const rootType = new GraphQLObjectType({
     starship: rootFieldByID('starshipID', 'starships'),
     allVehicles: rootConnection('Vehicles', 'vehicles'),
     vehicle: rootFieldByID('vehicleID', 'vehicles'),
+    machine: rootFieldByID('machineID', 'machines'),
+    allMachines: rootConnection('Machines', 'machines'),
     node: nodeField,
   }),
 });