LINE Login and Messaging

Before running this project

Setup LINE Developer Account and Channels

1. Create a development account

2. Create a Provider

3. Pick a provider

4. Create a LINE Login channel, fillout Basic Settings and Callback URL in the LINE Login section, it's the URL to which the user is redirected after logging in. (Configuring your channel)

5. Create a Messaging API channel and issue a Channel access token. We will use this channel access token to call the Messaging API.

Configure .env file

There are 4 keys to configure

• CLIENT_ID - from 4. -> Basic Settings section -> Channel ID
• CLIENT_SECRET - from 4. -> Basic Settings section -> Channel secret
• REDIRECT_URI - from 4. -> LINE Login section -> Callback URL
• CHANNEL_ACCESS_TOKEN - from 5 -> Messaging API -> Channel Access Token

Run

npm install
npm start

You can configure debug level in package.json, default are app:info and app:error

• app:error
• app:info
• app:debug

Making an Authorization Request

Handle user login at the route /

we will create a simple login link using 2 configurable params in our .env including 1 parameter generated by yourself.

1. client_id - it's a channel ID. Unique identifier for your channel issued by LINE.
2. redirect_uri - it's a callback URL. URL that users are redirected to after authentication and authorization. Must match one of the the callback URLs registered for your channel in the console
3. state - A unique alphanumeric string used to prevent cross-site request forgery. This value should be randomly generated by your application. Cannot be a URL-encoded string.

So, we need to begin with generating a state value and store it in session before sending it to views/index

app.get('/', (req, res) => {
  req.session.lineAuthState = Math.random().toString(36).replace(/[^a-z]+/g, '').substr(0, 10);
  res.status(200).render('index', {
    data: undefined,
    client_id: process.env.CLIENT_ID,
    redirect_uri: urlencode(process.env.REDIRECT_URI),
    state: req.session.lineAuthState
  })
})

the login link will be rendered in views/index.ejs

<a href="https://access.line.me/oauth2/v2.1/authorize?response_type=code&client_id=<%= client_id %>&redirect_uri=<%= redirect_uri %>&state=<%= state %>&scope=profile%20openid&bot_prompt=aggressive">Login</a>

We also added bot_prompt in the query parameters above and set its value to aggressive Read more

When user clicked the login link, the login process begins and in the end, the callback_uri will be hooked. in this demo, it's /line/auth_callback

REF: Making an authorization request

Handle Callback

Call back will be performed at /line/auth_callback route. Begin with verifying the state's value.

if (req.query.state !== req.session.lineAuthState) {
  return res.status(400).send('state error')
}

Get Access Token

Use code obtained from the callback request to get access_token

const data = {
    grant_type:'authorization_code',
    code: `${req.query.code}`,
    redirect_uri: `${process.env.REDIRECT_URI}`,
    client_id: `${process.env.CLIENT_ID}`,
    client_secret:`${process.env.CLIENT_SECRET}`
}

let response = await axios({
    method: 'post',
    url: 'https://api.line.me/oauth2/v2.1/token',
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8'
    },
    data: qs.stringify(data)
})

REF: Get Access Token

Get User Profile

use access_token to get user's profile

response = await axios({
  method: 'get',
  url: 'https://api.line.me/v2/profile',
  headers: {
      'Authorization': `Bearer ${loginData.access_token}`
  }
})

REF: Getting user profiles

Check Friendship Status

use access_token to get friendship status before sending a greeing message.

response = await axios({
  method: 'get',
  url: 'https://api.line.me/friendship/v1/status',
  headers: {
    'Authorization': `Bearer ${loginData.access_token}`
  }
})

Send a Greeting Mesage

Since the requested user is your friend then send a greeting message.

const payloadMessage = {
  to: loginData.userId,
  messages: [
      {
          type: 'text',
          text: 'Hello World! ' + new Date().toDateString()
      }
  ]
}
response = await axios({
  method: 'post',
  url: 'https://api.line.me/v2/bot/message/push',
  headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${process.env.CHANNEL_ACCESS_TOKEN}`
  },
  data: payloadMessage
})

REF: Push Message

Return to Home Screen

Send user back to / and show some user info.

res.status(200).render('index', {
  data: loginData,
  client_id: process.env.CLIENT_ID,
  redirect_uri: urlencode(process.env.REDIRECT_URI),
  state: req.session.lineAuthState
})