Zp/discriminator types

packages/openapi-to-graphql/src/schema_builder.ts

@@ -408,6 +408,26 @@ function createOrReuseUnion<TSource, TContext, TArgs>({
       description,
       types,
       resolveType: (source, context, info) => {
+
+        if (def.schema.discriminator) {
+          // Get the discriminator property name and then use that property to inspect
+          // the properties on the field that we have, matching the value to one of the
+          // type.
+
+          const componentName = source[def.schema.discriminator.propertyName]
+
+          const { mapping } = def.schema.discriminator
+
+          const type = types.find((type) => {
+            if (!mapping[componentName]) {
+              return false
+            }
+            return mapping[componentName].includes(type.name)
+          })
+          if (type) return type
+          return null
+        }
+
         const properties = Object.keys(source)
           // Remove custom _openAPIToGraphQL property used to pass data
           .filter((property) => property !== '_openAPIToGraphQL')

packages/openapi-to-graphql/src/types/oas3.ts

@@ -17,6 +17,7 @@ export type SchemaObject = {
   type?: 'string' | 'number' | 'integer' | 'boolean' | 'object' | 'array'
   format?: string
   nullable?: boolean
+  discriminator?: DiscriminatorObject
   description?: string
   properties?: {
     [key: string]: SchemaObject | ReferenceObject
@@ -63,6 +64,13 @@ type EncodingObject = {
   allowReserved?: boolean
 }
 
+type DiscriminatorObject = {
+  propertyName: string
+  mapping: {
+    [key: string]: string
+  }
+}
+
 export type MediaTypeObject = {
   schema?: SchemaObject | ReferenceObject
   example?: any

packages/openapi-to-graphql/test/discriminator_union.test.ts

@@ -0,0 +1,116 @@
+// Copyright IBM Corp. 2017,2018. All Rights Reserved.
+// Node module: openapi-to-graphql
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict'
+
+import { graphql } from 'graphql'
+import { afterAll, beforeAll, expect, test } from '@jest/globals'
+
+import * as openAPIToGraphQL from '../src/index'
+import { startServer, stopServer } from './discriminator_union_server'
+
+const oas = require('./fixtures/oneof_type_union.json')
+const PORT = 3004
+// Update PORT for this test case:
+oas.servers[0].variables.port.default = String(PORT)
+
+let createdSchema
+
+/**
+ * Set up the schema first and run example API server
+ */
+beforeAll(() => {
+  return Promise.all([
+    openAPIToGraphQL.createGraphQLSchema(oas).then(({ schema, report }) => {
+      console.log(report)
+      createdSchema = schema
+    }),
+    startServer(PORT)
+  ])
+})
+
+/**
+ * Shut down API server
+ */
+afterAll(() => {
+  return stopServer()
+})
+
+test('Querying a type union that uses a discriminator type', () => {
+  const query = `query {
+    shapes {
+      __typename
+      ... on SquareShapeOptions {
+        height
+        width
+      }
+      ... on RoundShapeOptions {
+        radius
+      }
+      ... on DotShapeOptions {
+        radius
+        x
+        y
+      }
+    }
+  }`
+  return graphql(createdSchema, query).then((result) => {
+    expect(result).toEqual({
+      data: {
+        shapes: [
+          {
+            __typename: 'SquareShapeOptions',
+            height: 10,
+            width: 20
+          },
+          {
+            __typename: 'RoundShapeOptions',
+            radius: 30
+          },
+          {
+            __typename: 'DotShapeOptions',
+            radius: 50,
+            x: 1,
+            y: 2
+          }
+        ]
+      }
+    })
+  })
+})
+
+// test('Posting a type union', () => {
+//   // Supposedly this is the best we can do with GraphQL mutations and type
+//   // unions?
+//   //
+//   // See https://github.com/graphql/graphql-spec/issues/488
+//   const query = `mutation {
+//     createShape (shapeOptionsPostInput: {
+//       type: "square"
+//       width: 50
+//       height: 50
+//     }) {
+//       __typename
+//       ... on SquareShapeOptions {
+//         height
+//         width
+//       }
+//       ... on RoundShapeOptions {
+//         radius
+//       }
+//     }
+//   }`
+//   return graphql(createdSchema, query).then((result) => {
+//     expect(result).toEqual({
+//       data: {
+//         createShape: {
+//           __typename: 'SquareShapeOptions',
+//           height: 50,
+//           width: 50
+//         }
+//       }
+//     })
+//   })
+// })

packages/openapi-to-graphql/test/discriminator_union_server.js

@@ -0,0 +1,72 @@
+// Copyright IBM Corp. 2017,2018. All Rights Reserved.
+// Node module: openapi-to-graphql
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict'
+
+let server // holds server object for shutdown
+
+/**
+ * Starts the server at the given port
+ */
+function startServer(PORT) {
+  const express = require('express')
+  const app = express()
+
+  const bodyParser = require('body-parser')
+  app.use(bodyParser.json())
+
+  app.get('/api/shapes', (req, res) => {
+    res.send([
+      {
+        type: 'square',
+        height: 10,
+        width: 20
+      },
+      {
+        type: 'round',
+        radius: 30
+      },
+      {
+        type: 'dot',
+        radius: 50,
+        x: 1,
+        y: 2
+      }
+    ])
+  })
+
+  app.post('/api/shapes', (req, res) => {
+    res.send(req.body)
+  })
+
+  return new Promise((resolve) => {
+    server = app.listen(PORT, () => {
+      console.log(`Example API accessible on port ${PORT}`)
+      resolve()
+    })
+  })
+}
+
+/**
+ * Stops server.
+ */
+function stopServer() {
+  return new Promise((resolve) => {
+    server.close(() => {
+      console.log(`Stopped API server`)
+      resolve()
+    })
+  })
+}
+
+// If run from command line, start server:
+if (require.main === module) {
+  startServer(3002)
+}
+
+module.exports = {
+  startServer,
+  stopServer
+}