fix: adding tests and comments illustrating the discriminator bug issue

Signed-off-by: Philip Noebauer <[email protected]>

Author: pnoebauer

examples/validation-app/src/__tests__/acceptance/validate-discriminator.acceptance.ts

@@ -0,0 +1,75 @@
+// Copyright IBM Corp. and LoopBack contributors 2020. All Rights Reserved.
+// Node module: @loopback/example-validation-app
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {Client, expect} from '@loopback/testlab';
+import {ValidationApplication} from '../..';
+import {setupApplication} from './test-helper';
+
+const validCat = {
+  name: 'Kitty',
+  weight: 5,
+  kind: 'Cat',
+  animalProperties: {
+    color: 'grey',
+    whiskerLength: 2,
+  },
+};
+
+const validDog = {
+  name: 'Rex',
+  weight: 5,
+  kind: 'Dog',
+  animalProperties: {
+    breed: 'poodle',
+    barkVolume: 5,
+  },
+};
+
+describe('validate properties', () => {
+  let client: Client;
+  let app: ValidationApplication;
+
+  before(givenAClient);
+
+  after(async () => {
+    await app.stop();
+  });
+
+  async function givenAClient() {
+    ({app, client} = await setupApplication());
+  }
+
+  it('should pass with valid cat properties', async () => {
+    await client.post('/pets').send(validCat).expect(200);
+  });
+
+  it('should pass with valid dog properties', async () => {
+    await client.post('/pets').send(validDog).expect(200);
+  });
+
+  it('should fail with error indicating the invalid barkVolume', async () => {
+    const invalidDog = {...validDog};
+    invalidDog.animalProperties.barkVolume = 'loud' as unknown as number;
+    const response = await client.post('/pets').send(invalidDog).expect(422);
+
+    /*
+      below expect statements pass after fixing the bug in function convertToJsonSchema()
+      loopback-next/packages/rest/src/validation/request-body.validator.ts#lines-87:99
+      a possible solution is indicated under //NOTE
+    */
+    expect(response.body.error.details.length).to.equal(1);
+    expect(response.body.error.details[0].message).to.equal('must be number');
+    expect(response.body.error.details).to.deepEqual([
+      {
+        code: 'type',
+        info: {
+          type: 'number',
+        },
+        message: 'must be number',
+        path: '/animalProperties/barkVolume',
+      },
+    ]);
+  });
+});

examples/validation-app/src/controllers/pet.controller.ts

@@ -9,24 +9,12 @@ import {Cat, Dog, Pet} from '../models';
 export class PetController {
   constructor() {}
 
-  @post('/pets', {
-    responses: {
-      '200': {
-        description: 'Pet model instance',
-        content: {
-          'application/json': {
-            schema: {'x-ts-type': Pet},
-          },
-        },
-      },
-    },
-  })
+  @post('/pets')
   async create(
     @requestBody({
       content: {
         'application/json': {
           schema: {
-            required: ['kind'],
             discriminator: {
               propertyName: 'kind',
             },

examples/validation-app/src/models/pet.model.ts

@@ -10,9 +10,9 @@ export class CatProperties extends Model {
 
   @property({
     type: Number,
-    required: false,
+    required: true,
   })
-  whiskerLength?: number;
+  whiskerLength: number;
 }
 
 @model()
@@ -25,9 +25,9 @@ export class DogProperties extends Model {
 
   @property({
     type: Number,
-    required: false,
+    required: true,
   })
-  barkVolume?: number;
+  barkVolume: number;
 }
 
 @model()

packages/rest/src/validation/request-body.validator.ts

@@ -84,10 +84,18 @@ export async function validateRequestBody(
  * @param openapiSchema - The OpenAPI schema to convert.
  */
 function convertToJsonSchema(openapiSchema: SchemaObject) {
-  // const jsonSchema = toJsonSchema(openapiSchema);
-  const jsonSchema = toJsonSchema(openapiSchema, {
-    keepNotSupported: ['discriminator'],
-  });
+  /*
+    loopback does not pass the options arg to function toJsonSchema(schema, options?),
+    which is part of the openapi-schema-to-json-schema library;
+    by default toJsonSchema() removes discriminators, which is why they do not work
+    in loopback
+  */
+  // TODO: fix below bug; toJsonSchema requires the options object to enable discriminators
+  const jsonSchema = toJsonSchema(openapiSchema);
+  // NOTE: replacing above line with below fixes discriminators not working in loopback and all tests pass
+  // const jsonSchema = toJsonSchema(openapiSchema, {
+  //   keepNotSupported: ['discriminator'],
+  // });
 
   delete jsonSchema['$schema'];
   /* istanbul ignore if */