How to create the App Home view and use a modal
Your Slack app's App Home is a focused, 1:1 space in Slack shared between individual users and your app. Within every App Home, users can view the About, Messages, and Home tabs.
The Home tab is a dynamic and persistent visual interface allowing users to interact privately with your app. Your app can greet users, showcase customized content, or even be a little playful!
Wait, don’t I already have an App Home? This feature may sound familiar to you! We've had an event called app_home_opened for some time, triggered when a user selects an app from the left-hand menu. It's a great opportunity to welcome a user with a message containing timely information.
With the Home tab, your app can go beyond messaging to display more organized, dynamic content with blocks in a persistent location independent of conversation.
App Home tab
This is what the surface area looks like for the Google Calendar Slack app:
- Home tab: view your daily calendar, where you can modify your invitation response or join a conference call on Zoom.
- Messages tab: where the app sends you direct messages. For example, in Google Calendar, the app notifies you by sending a message 1 minute before a meeting.
- About tab: where you can view information about the app.
Creating an App Home
To demonstrate what you can do with App Home, we'll take a look at an app called Stickies, which allows users to store short, private notes within the App Home. The user and app flows are described below.
User flow
- A user clicks the name of the app under Apps within their Slack client (the Home tab should be opened by default).
- The user can add a new note by clicking the button in the pane.
- The user fills out the form in a modal window, then clicks Create.
- The Home tab is automatically updated with the new note entry.
App flow
- When a user opens the App Home, the
app_home_openedevent gets triggered and sent to the app server. - The app uses the user ID from the event payload to display the initial view with a button using the
views.publishAPI method. - When the user clicks Add a Stickie, an interaction is triggered.
- The app opens a modal with form inputs using the
views.openAPI method. - Once the user submits the form, another interaction is triggered with a type of
view_submission. - The App Home is updated using the
views.publishAPI method.
Now, let’s create the Stickies app for your workspace. The source code of the app is on Glitch, where you can remix and run without deploying any code. Select the magnifying glass at the top of the page, enter Stickies into the search, and hit Enter. Select the Stickies app when it appears in the results, then click View Source to view its source code.
Setting up your app
To set up your app on Slack, navigate to Slack App Management to create an app — or, click the button below:
- Navigate to Features > OAuth & Permissions to specify your bot token scopes and select
chat:write. Technically, our sample app doesn't send any messages, but just follow along for now. To learn more about this new more granular bot permission model, refer to Installing with OAuth. - Navigate to Features > App Home and enable the Home tab.
- Navigate to Features > Event Subscriptions to enable events (see Step 1 in the screenshot below).
- Enter your Request URL (step 2). If you remixed the example Glitch code, your Request URL should be
https://your-project.glitch.me/slack/events. Glitch generates a project name when you create a project, so you'll have a project name composed of two or three random words, such as obtainable-lovely-friday. You can also customize the project name. If you're running on your own server, append/slack/eventsto the URL. - Scroll down to the Subscribe to bot events section to add the
app_home_openedevent (step 3). - Click Save Changes (step 4).
- Navigate to Features > Interactivity & Shortcuts to tell Slack where to send interactive payloads. Use your Request URL,
https://your-project.glitch.me/slack/actions, then save your changes. - Install the app: navigate to the Install App section and click Install to Workspace to install the app to your workspace. Follow the prompts, and once the installation process is finished, you'll have your OAuth access tokens available.
- Get ready with your Glitch project window in your browser or IDE. Select the
.envfile. This is where your environment variables are stored. Copy the bot token, which begins withxoxb, and paste it into the variableSLACK_BOT_TOKEN. - In the Slack app settings page, get your Signing secret from within Settings > Basic Information. Copy and paste it to the
.envfile as well.
Displaying the App Home
Setting up your Express server
In this tutorial, we'll use Node.js with Express as the web server. All API calls are made with straightforward HTTP requests and responses. Hopefully, the code is readily comprehensible for any language you use.
⚡️ If you prefer developing with Bolt for JavaScript framework, the source code is also available. Note that this tutorial uses “vanilla” JS code!
In your Node.js code, include dependencies and spin up your Express server. You'll need to evaluate the raw request payload to verify the signing secret from Slack. The index.js file shows how to run a server with Express and demonstrates checking the HTTP headers to verify request signature. For more details about using signing secret with Express and Body Parser in Node.js, refeer to Verifying the Requests.
Triggering the app_home_opened event
Use an HTTP POST method route to create an endpoint to receive the event payload. This is where Slack API server sends you a JSON payload when an event is fired. Once you receive the data, check whether the event type is app_home_opened, then prepare to display the App Home view.
Here is the code snippet from index.js:
app.post('/slack/events', async(req, res) => {
switch (req.body.type) {
case 'url_verification': {
// verify Events API endpoint by returning challenge if present
res.send({ challenge: req.body.challenge });
break;
}
case 'event_callback': {
// Verify the signing secret
if (!signature.isVerified(req)) {
res.sendStatus(404);
return;
}
// Request is verified --
else {
const {type, user, channel, tab, text, subtype} = req.body.event;
// Triggered when the App Home is opened by a user
if(type === 'app_home_opened') {
// Display App Home
appHome.displayHome(user);
}
Let’s display a rich content in App Home view with rich message layout, Block Kit:
const displayHome = async(user, data) => {
const args = {
token: process.env.SLACK_BOT_TOKEN,
user_id: user,
view: await updateView(user)
};
const result = await axios.post('/views.publish', qs.stringify(args));
};
To display content in the App Home, call the view.publish API method. In this example, we'll use the axios module to handle the API calls via HTTP POST.
Constructing the view with Block Kit
We'll call another function to create JSON to construct the view to be displayed. This function can be reused when you update the view when new content is added later. This code snippet shows how to build and display the initial view:
const updateView = async(user) => {
let blocks = [
{
// Section with text and a button
type: "section",
text: {
type: "mrkdwn",
text: "*Welcome!* \nThis is a home for Stickers app. You can add small notes here!"
},
accessory: {
type: "button",
action_id: "add_note",
text: {
type: "plain_text",
text: "Add a Stickie"
}
}
},
// Horizontal divider line
{
type: "divider"
}
];
let view = {
type: 'home',
title: {
type: 'plain_text',
text: 'Keep notes!'
},
blocks: blocks
}
return JSON.stringify(view);
};
The blocks array definied in the code snippet above is prototyped with Block Kit Builder.
In the actual source code, the function is dynamic, and it takes additional content from the interactive button and modal.
Handling user interaction
Once a user clicks the button, a modal opens.
Notice that the action_id is specified in the message building block. Use the identifier to retrieve the data we need. Once a user clicks the button, the API server sends your Request URL a payload for the user action, which contains a trigger_id. You'll need this to open a modal.
app.post('/slack/actions', async(req, res) => {
const { token, trigger_id, user, actions, type } = JSON.parse(req.body.payload);
if(actions && actions[0].action_id.match(/add_/)) {
openModal(trigger_id);
}
});
Opening a modal
This is how you create form elements (input box and a drop-down menu with a submit button) in a modal view. For this example, we'll make a form with a multi-line text input and a pick-a-color dropdown.
To open the modal, call the views.open API method:
const openModal = async(trigger_id) => {
const modal = {
type: 'modal',
title: {
type: 'plain_text',
text: 'Create a stickie note'
},
submit: {
type: 'plain_text',
text: 'Create'
},
blocks: [
// Text input
{
"type": "input",
"block_id": "note01",
"label": {
"type": "plain_text",
"text": "Note"
},
"element": {
"action_id": "content",
"type": "plain_text_input",
"placeholder": {
"type": "plain_text",
"text": "Take a note... "
},
"multiline": true
}
},
// Drop-down menu
{
"type": "input",
"block_id": "note02",
"label": {
"type": "plain_text",
"text": "Color",
},
"element": {
"type": "static_select",
"action_id": "color",
"options": [
{
"text": {
"type": "plain_text",
"text": "yellow"
},
"value": "yellow"
},
{
"text": {
"type": "plain_text",
"text": "blue"
},
"value": "blue"
}
]
}
}
]
};
const args = {
token: process.env.SLACK_BOT_TOKEN,
trigger_id: trigger_id,
view: JSON.stringify(modal)
};
const result = await axios.post('https://slack.com/api/views.open', qs.stringify(args));
};
The code snippet seems long, but as you can see, it's mostly just constructing a JSON for the form UI. See how it's built on Block Kit Builder.
Handling the form submission
The submission from a user is handled in the same way the button click from the Home tab was handled.
When the form in the modal is submitted, a payload is sent to the same endpoint of the action. You can differentiate the submission by checking the type in the payload data. The full code snippet from the index.js file is below:
app.post('/slack/actions', async(req, res) => {
//console.log(JSON.parse(req.body.payload));
const { token, trigger_id, user, actions, type } = JSON.parse(req.body.payload);
// Button with "add_" action_id clicked --
if(actions && actions[0].action_id.match(/add_/)) {
// Open a modal window with forms to be submitted by a user
appHome.openModal(trigger_id);
}
// Modal forms submitted --
else if(type === 'view_submission') {
res.send(''); // Make sure to respond to the server to avoid an error
const ts = new Date();
const { user, view } = JSON.parse(req.body.payload);
const data = {
timestamp: ts.toLocaleString(),
note: view.state.values.note01.content.value,
color: view.state.values.note02.color.selected_option.value
}
appHome.displayHome(user.id, data);
}
});
Updating the App Home view
Append the newly acquired data from the user to the current view block, and re-render the Home tab view using the views.publish API method.
In this example, we're using a persistent database with the node-json-db module. Each time a user adds a new note, the data is pushed to the data array. We'll create a new data block in JSON, then append it to the existing JSON, and finally display the new view by calling the views.publish API method.
You can see the source code in the appHome.js file below:
const updateView = async(user) => {
// Intro message -
let blocks = [
{
type: "section",
text: {
type: "mrkdwn",
text: "Hello! Make a note of things you don't want to forget."
},
accessory: {
type: "button",
action_id: "add_note",
text: {
type: "plain_text",
text: "Add sticky note",
emoji: true
}
}
},
{
type: "divider"
}
];
// Append new data blocks after the intro -
let newData = [];
try {
const rawData = db.getData(`/${user}/data/`);
newData = rawData.slice().reverse(); // Reverse to make the latest first
newData = newData.slice(0, 50); // Just display 20. Block Kit display has some limit.
} catch(error) {
//console.error(error);
};
if(newData) {
let noteBlocks = [];
for (const o of newData) {
const color = (o.color) ? o.color : 'yellow';
let note = o.note;
if (note.length > 3000) {
note = note.substr(0, 2980) + '... _(truncated)_'
console.log(note.length);
}
noteBlocks = [
{
type: "section",
text: {
type: "mrkdwn",
text: note
},
accessory: {
type: "image",
image_url: `https://cdn.glitch.com/0d5619da-dfb3-451b-9255-5560cd0da50b%2Fstickie_${color}.png`,
alt_text: "stickie note"
}
},
{
"type": "context",
"elements": [
{
"type": "mrkdwn",
"text": o.timestamp
}
]
},
{
type: "divider"
}
];
blocks = blocks.concat(noteBlocks);
}
}
// The final view -
let view = {
type: 'home',
title: {
type: 'plain_text',
text: 'Keep notes!'
},
blocks: blocks
}
return JSON.stringify(view);
};
/* Display App Home */
const displayHome = async(user, data) => {
if(data) {
// Store in a local DB
db.push(`/${user}/data[]`, data, true);
}
const args = {
token: process.env.SLACK_BOT_TOKEN,
user_id: user,
view: await updateView(user)
};
const result = await axios.post(`${apiUrl}/views.publish`, qs.stringify(args));
try {
if(result.data.error) {
console.log(result.data.error);
}
} catch(e) {
console.log(e);
}
};
Try it out
To enable your app, go to your Slack workspace, choose Apps from the sidebar menu, and select your app. See how the App Home view works by playing around with the app!
