96 lines
2.8 KiB
Markdown
96 lines
2.8 KiB
Markdown
# Step 7: Share Code
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## Video of this Lesson
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<iframe width="560" height="600" src="https://www.youtube.com/embed/-zzw4_oT_2I" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
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Awesome! The application is working end to end! However, there is a problem. Both the backend and the frontend define the `Todo` interface. The interface is in sync now, but in a real application, over time, it will diverge, and, as a result, runtime errors will creep in. You should share this interface between the backend and the frontend. In Nx, you can do this by creating a library.
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**Run the following generator to create a library:**
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```bash
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npx nx g @nrwl/workspace:lib data
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```
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The result should look like this:
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```treeview
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myorg/
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├── apps/
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│ ├── todos/
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│ ├── todos-e2e/
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│ └── api/
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├── libs/
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│ └── data/
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│ ├── src/
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│ │ ├── lib/
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│ │ │ └── data.ts
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│ │ └── index.ts
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│ ├── jest.conf.js
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│ ├── tsconfig.app.json
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│ ├── tsconfig.json
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│ └── tsconfig.spec.json
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├── tools/
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├── nx.json
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├── package.json
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└── tsconfig.json
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```
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**Copy the interface into `libs/data/src/lib/data.ts`.**
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```typescript
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export interface Todo {
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title: string;
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}
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```
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### A note about VS Code :
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If you're using [VS Code](https://code.visualstudio.com/) it may be necessary at this point to restart the TS server so that the new `@myorg/data` package is recognised. This may need to be done **every time a new workspace library is added**.
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## Refactor the API
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**Now update `apps/api/src/app/todos.ts` to import the interface:**
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```typescript
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import { Express } from 'express';
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import { Todo } from '@myorg/data';
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const todos: Todo[] = [{ title: 'Todo 1' }, { title: 'Todo 2' }];
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export function addTodoRoutes(app: Express) {
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app.get('/api/todos', (req, resp) => resp.send(todos));
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app.post('/api/addTodo', (req, resp) => {
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const newTodo = {
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title: `New todo ${Math.floor(Math.random() * 1000)}`,
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};
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todos.push(newTodo);
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resp.send(newTodo);
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});
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}
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```
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## Update the React Application
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**Next import the interface in `apps/todos/src/app/app.tsx`:**
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```typescript jsx
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import React, { useEffect, useState } from 'react';
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import { Todo } from '@myorg/data';
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export const App = () => {
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...
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};
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export default App;
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```
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Every time you add a new library, you have to restart `npx nx serve`. **So restart both `npx nx serve api` and `npx nx serve todos` and you should see the application running.**
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!!!!!
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Nx allows you to share code...
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!!!!!
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Between frontend and backend apps
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Between different frontend apps
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Between different node apps
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