# Create an API

## Lesson Objectives

1. Define API
1. Initialize Directory
1. Set Up Express Server
1. Create Todo Controller
1. Initialize Mongoose
1. Create Todo Model
1. Create Create Route
1. Create Index Route
1. Create Delete Route
1. Create Update Route

## Define API

- An API stands for Application Program Interface
- It is a set of routines, protocols, and tools for building software applications
- It specifies how software components should interact
- Essentially it's documentation, but in the industry, it's come to mean a program or some existing software that you use to build your own app

## Initialize Directory

1. `npm init`
1. set entry point as server.js
1. `touch server.js`
1. `npm install express`

## Set Up Express Server

server.js:

```javascript
const express = require('express');
const app = express();

app.listen(3000, ()=>{
    console.log('listening...');
});
```

## Create Todo Controller

1. `mkdir controllers`
1. `touch controllers/todos.js`

controllers/todos.js:

```javascript
const express = require('express');
const router = express.Router();

router.get('/', (req, res)=>{
    res.send('index');
});

module.exports = router;
```

server.js:

```javascript
const todosController = require('./controllers/todos.js');
app.use('/todos', todosController);
```

## Initialize Mongoose

1. `npm install mongoose`

server.js:

```javascript
const mongoose = require('mongoose');
//...farther down the page
mongoose.connect('mongodb://localhost:27017/meancrud', { useNewUrlParser: true, useUnifiedTopology: true });
mongoose.connection.once('open', ()=>{
    console.log('connected to mongod...');
});
```

Open terminal tabs for `mongod` and `mongo`

## Create Todo Model

1. `mkdir models`
1. `touch models/todos.js`

models/todos.js:

```javascript
const mongoose = require('mongoose');

const todoSchema = new mongoose.Schema({
    description: String,
    complete: Boolean
});

const Todos = mongoose.model('Todo', todoSchema);

module.exports = Todos;
```

## Create Create Route

1. We need to tell Express to expect JSON data in the body from AJAX, so we'll use `express.json()`
1. We'll also need to tell the client that the data coming back is JSON, not HTML, so we'll do `res.json()`

server.js:

```javascript
app.use(express.json()); //use .json(), not .urlencoded()
```

controllers/todos.js

```javascript
const Todos = require('../models/todos.js');
//...farther down the page
router.post('/', (req, res)=>{
    Todos.create(req.body, (err, createdTodo)=>{
        res.json(createdTodo); //.json() will send proper headers in response so client knows it's json coming back
    });
});
```

test: `curl -X POST -H "Content-Type: application/json" -d '{"description":"weee","complete":true}' http://localhost:3000/todos`

## Create Index Route

controllers/todos.js:

```javascript
router.get('/', (req, res)=>{
    Todos.find({}, (err, foundTodos)=>{
        res.json(foundTodos);
    });
});
```

test: `curl http://localhost:3000/todos`

## Create Delete Route

```javascript
router.delete('/:id', (req, res)=>{
    Todos.findByIdAndRemove(req.params.id, (err, deletedTodo)=>{
        res.json(deletedTodo);
    });
});
```

test: `curl -X DELETE http://localhost:3000/todos/58f79d490708714536c02474`

## Create Update Route

controllers/todos.js:

```javascript
router.put('/:id', (req, res)=>{
    Todos.findByIdAndUpdate(req.params.id, req.body, {new:true}, (err, updatedTodo)=>{
        res.json(updatedTodo);
    });
});
```

test: `curl -X PUT -H "Content-Type: application/json" -d '{"description":"I updated this","complete":true}' http://localhost:3000/todos/58f7a4fd26b1a345e9281cb8`