fix: send 404 for findById(), if resource is not found

send 404 for findById(), if resource is not found

examples/todo/src/controllers/todo.controller.ts

@@ -5,7 +5,16 @@
 
 import {inject} from '@loopback/core';
 import {repository} from '@loopback/repository';
-import {del, get, param, patch, post, put, requestBody} from '@loopback/rest';
+import {
+  del,
+  get,
+  param,
+  patch,
+  post,
+  put,
+  requestBody,
+  throwNotFoundErrorWhenNull,
+} from '@loopback/rest';
 import {Todo} from '../models';
 import {TodoRepository} from '../repositories';
 import {GeocoderService} from '../services';
@@ -35,7 +44,9 @@ export class TodoController {
     @param.path.number('id') id: number,
     @param.query.boolean('items') items?: boolean,
   ): Promise<Todo> {
-    return await this.todoRepo.findById(id);
+    const result = await this.todoRepo.findById(id);
+    throwNotFoundErrorWhenNull(result);
+    return result;
   }
 
   @get('/todos')

packages/rest/src/index.ts

@@ -31,6 +31,7 @@ export * from './rest.component';
 export * from './rest.server';
 export * from './sequence';
 export * from './rest-http-error';
+export * from './utils';
 
 // export all errors from external http-errors package
 import * as HttpErrors from 'http-errors';

packages/rest/src/utils.ts

@@ -0,0 +1,16 @@
+import * as HttpErrors from 'http-errors';
+
+export function throwNotFoundErrorWhenNull(model: null): never;
+export function throwNotFoundErrorWhenNull<T>(model: T): void;
+
+export function throwNotFoundErrorWhenNull<T>(model: T | null): T {
+  if (model) return model;
+  // WIP: don't mind these temporary hard-coded values
+  const modelName = '';
+  const id = 2;
+  const msg = `Unknown "${modelName}" id "${id}".`;
+  const error = new HttpErrors.HttpError(msg);
+  error.statusCode = error.status = 404;
+  error.code = 'MODEL_NOT_FOUND';
+  throw error;
+}