fix: illustrate the discriminator bug and fix in loopback rest request-body-validator

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

Author: pnoebauer

examples/validation-app/src/application.ts

@@ -6,7 +6,7 @@
 import {BootMixin} from '@loopback/boot';
 import {ApplicationConfig, createBindingFromClass} from '@loopback/core';
 import {RepositoryMixin} from '@loopback/repository';
-import {RestApplication} from '@loopback/rest';
+import {RestApplication, RestBindings} from '@loopback/rest';
 import {
   RestExplorerBindings,
   RestExplorerComponent,
@@ -32,6 +32,12 @@ export class ValidationApplication extends BootMixin(
     // Set up default home page
     this.static('/', path.join(__dirname, '../public'));
 
+    this.bind(RestBindings.REQUEST_BODY_PARSER_OPTIONS).to({
+      validation: {
+        discriminator: true,
+      },
+    });
+
     // Customize @loopback/rest-explorer configuration here
     this.configure(RestExplorerBindings.COMPONENT).to({
       path: '/explorer',

examples/validation-app/src/controllers/index.ts

@@ -4,3 +4,4 @@
 // License text available at https://opensource.org/licenses/MIT
 
 export * from './coffee-shop.controller';
+export * from './pet.controller';

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

@@ -0,0 +1,42 @@
+// 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 {post, requestBody} from '@loopback/rest';
+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},
+          },
+        },
+      },
+    },
+  })
+  async create(
+    @requestBody({
+      content: {
+        'application/json': {
+          schema: {
+            required: ['kind'],
+            discriminator: {
+              propertyName: 'kind',
+            },
+            oneOf: [{'x-ts-type': Cat}, {'x-ts-type': Dog}],
+          },
+        },
+      },
+    })
+    request: Pet,
+  ): Promise<Pet> {
+    return request;
+  }
+}

examples/validation-app/src/middleware/validation-error.middleware.ts

@@ -54,7 +54,10 @@ export class ValidationErrorMiddlewareProvider implements Provider<Middleware> {
     err: HttpErrors.HttpError,
   ): Response | undefined {
     // 2. customize error for particular endpoint
-    if (context.request.url === '/coffee-shops') {
+    if (
+      context.request.url === '/coffee-shops' ||
+      context.request.url === '/pets'
+    ) {
       // if this is a validation error from the PATCH method, customize it
       // for other validation errors, the default AJV error object will be sent
       if (err.statusCode === 422 && context.request.method === 'PATCH') {

examples/validation-app/src/models/index.ts

@@ -4,3 +4,4 @@
 // License text available at https://opensource.org/licenses/MIT
 
 export * from './coffee-shop.model';
+export * from './pet.model';

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

@@ -0,0 +1,86 @@
+import {Model, model, property} from '@loopback/repository';
+
+@model()
+export class CatProperties extends Model {
+  @property({
+    type: String,
+    required: true,
+  })
+  color: string;
+
+  @property({
+    type: Number,
+    required: false,
+  })
+  whiskerLength?: number;
+}
+
+@model()
+export class DogProperties extends Model {
+  @property({
+    type: String,
+    required: true,
+  })
+  breed: string;
+
+  @property({
+    type: Number,
+    required: false,
+  })
+  barkVolume?: number;
+}
+
+@model()
+export class Pet extends Model {
+  @property({
+    type: String,
+    required: true,
+  })
+  name: string;
+
+  @property({
+    type: Number,
+    required: false,
+  })
+  weight?: number;
+
+  kind: string;
+
+  animalProperties: CatProperties | DogProperties;
+}
+
+@model()
+export class Dog extends Pet {
+  @property({
+    type: String,
+    jsonSchema: {
+      enum: ['Dog'],
+    },
+    required: true,
+  })
+  kind: string;
+
+  @property({
+    type: DogProperties,
+    required: true,
+  })
+  animalProperties: DogProperties;
+}
+
+@model()
+export class Cat extends Pet {
+  @property({
+    type: String,
+    jsonSchema: {
+      enum: ['Cat'],
+    },
+    required: true,
+  })
+  kind: string;
+
+  @property({
+    type: CatProperties,
+    required: true,
+  })
+  animalProperties: CatProperties;
+}

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

@@ -84,7 +84,11 @@ export async function validateRequestBody(
  * @param openapiSchema - The OpenAPI schema to convert.
  */
 function convertToJsonSchema(openapiSchema: SchemaObject) {
-  const jsonSchema = toJsonSchema(openapiSchema);
+  // const jsonSchema = toJsonSchema(openapiSchema);
+  const jsonSchema = toJsonSchema(openapiSchema, {
+    keepNotSupported: ['discriminator'],
+  });
+
   delete jsonSchema['$schema'];
   /* istanbul ignore if */
   if (debug.enabled) {