Creating a Gmail Add-on

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Creating a Gmail Add-on

45 minutes 1 Credit


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Gmail add-ons automate tasks within Gmail, saving time and effort for users. Gmail add-ons can examine incoming messages, then act on these messages in various ways, such as:

  • Displaying additional information for the user in the Gmail UI.

  • Connecting to non-Google services, to retrieve information or take other actions.

  • Providing an interactive interface to allow the user to control the add-on or send information to another service.

What you'll do

In this hands-on lab you create a Gmail Add-on that allows you to quickly change the labels of an email thread.

Setup and requirements

Before you click the Start Lab button

Read these instructions. Labs are timed and you cannot pause them. The timer, which starts when you click Start Lab, shows how long lab resources will be made available to you.

This Qwiklabs hands-on lab lets you do the lab activities yourself in a real cloud environment, not in a simulation or demo environment. It does so by giving you new, temporary credentials that you use to sign in and access Gmail for the duration of the lab.

What you need

To complete this lab, you need:

  • Access to a standard internet browser (Chrome browser recommended).

  • Time to complete the lab.

  1. Make sure you are signed into Qwiklabs using an incognito window.

  2. When ready, click start lab button.

    A new panel appears with the temporary credentials that you must use for this lab.

    If you need to pay for the lab, a pop-up will open for you to select your payment method.

  3. Note your lab credentials. You use them to sign in to Gmail for this lab.

    If you use other credentials, you will get errors or incur charges.
  4. Click Open Gmail.

  5. Click Next in the Sign in dialog.

  6. Enter the Qwiklabs provided Password and click Next.

  7. If needed, click Accept to accept the terms.

Gmail opens. Click Get started, and then close any further information windows.

You are now in Gmail, looking at your Inbox.

Task 1. Create the script project

Launch Apps Script

  1. Click this link to Apps Script to open in a new tab or browser window. A new project opens.
Note: Apps Script places the project file in your Drive root folder.
  1. Click Use classic editor.

  2. Click Dismiss in the Try the brand new Apps Script editor! dialog.

Name the project

  1. Click Untitled project in the upper left.

  2. Name the project Gmail Add-on Quickstart, and then click OK.

Create the script file,

  1. Replace the file contents with the following:

/** * Copyright Google LLC * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /** * Returns the array of cards that should be rendered for the current * e-mail thread. The name of this function is specified in the * manifest 'onTriggerFunction' field, indicating that this function * runs every time the add-on is started. * * @param {Object} e The data provided by the Gmail UI. * @return {Card[]} */ function buildAddOn(e) { // Activate temporary Gmail add-on scopes. var accessToken = e.messageMetadata.accessToken; GmailApp.setCurrentMessageAccessToken(accessToken); var messageId = e.messageMetadata.messageId; var message = GmailApp.getMessageById(messageId); // Get user and thread labels as arrays to enable quick sorting and indexing. var threadLabels = message.getThread().getLabels(); var labels = getLabelArray(GmailApp.getUserLabels()); var labelsInUse = getLabelArray(threadLabels); // Create a section for that contains all user Labels. var section = CardService.newCardSection() .setHeader("<font color=\"#1257e0\"><b>Available User Labels</b></font>"); // Create a checkbox group for user labels that are added to prior section. var checkboxGroup = CardService.newSelectionInput() .setType(CardService.SelectionInputType.CHECK_BOX) .setFieldName('labels') .setOnChangeAction(CardService.newAction().setFunctionName('toggleLabel')); // Add checkbox with name and selected value for each User Label. for(var i = 0; i < labels.length; i++) { checkboxGroup.addItem(labels[i], labels[i], labelsInUse.indexOf(labels[i])!= -1); } // Add the checkbox group to the section. section.addWidget(checkboxGroup); // Build the main card after adding the section. var card = CardService.newCardBuilder() .setHeader(CardService.newCardHeader() .setTitle('Quick Label') .setImageUrl('')) .addSection(section) .build(); return [card]; } /** * Updates the labels on the current thread based on * user selections. Runs via the OnChangeAction for * each CHECK_BOX created. * * @param {Object} e The data provided by the Gmail UI. */ function toggleLabel(e){ var selected = e.formInputs.labels; // Activate temporary Gmail add-on scopes. var accessToken = e.messageMetadata.accessToken; GmailApp.setCurrentMessageAccessToken(accessToken); var messageId = e.messageMetadata.messageId; var message = GmailApp.getMessageById(messageId); var thread = message.getThread(); if (selected != null){ for each (var label in GmailApp.getUserLabels()) { if(selected.indexOf(label.getName()) != -1){ thread.addLabel(label); } else { thread.removeLabel(label); } } } else { for each (var label in GmailApp.getUserLabels()) { thread.removeLabel(label); } } } /** * Converts an GmailLabel object to a array of strings. * Used for easy sorting and to determine if a value exists. * * @param {labelsObjects} A GmailLabel object array. * @return {lables[]} An array of labels names as strings. */ function getLabelArray(labelsObjects){ var labels = []; for(var i = 0; i < labelsObjects.length; i++) { labels[i] = labelsObjects[i].getName(); } labels.sort(); return labels; }
  1. Before saving, you'll need to update the script manifest to avoid errors.

Task 2. Update the script manifest

Update the manifest (appsscript.json) to provide the add-on with required deployment information.

  1. In the script editor, select the View > Show manifest file menu item.

  2. Name your project Gmail Add-on Quickstart, and click OK. This opens the manifest file, appsscript.json in the editor.

  3. Replace the content of the manifest (appsscript.json)with the following:


{ "oauthScopes": [ "", "", "" ], "gmail": { "name": "Gmail Add-on Quickstart - QuickLabels", "logoUrl": "", "contextualTriggers": [{ "unconditional": { }, "onTriggerFunction": "buildAddOn" }], "openLinkUrlPrefixes": [ "" ], "primaryColor": "#4285F4", "secondaryColor": "#4285F4" } }
  1. Select File > Save all to save these changes to the manifest and This step provides the add-on with required deployment information. If you get an error, save again.
Create a new Apps Script project

Task 3. Deploy the add-on

  1. In the script editor, select Publish > Deploy from manifest....
  2. In the Deployments dialog, click the Install add-on link.
  3. After receiving the Deployment installed message, click Close. Creating a new deployment is not necessary, as you are using the head deployment only.
  4. Open the Gmail add-on settings tab.
  5. This brings you to the Setting dialog at the Add-ons tab.


When you have completed these steps, the add-on appears in the Installed developer add-ons list and becomes available for use in Gmail.


If you don't see your add-on in the Installed developer add-ons list, refresh the brower window. If the add-on is still not in the list, return to the Gmail Add-on Quickstart tab, uninstall and reinstall the add-on from the Publish > Deploy from manifest... window.

Task 4. Run the add-on

  1. Return to your Gmail tab and refresh the tab.
  2. Choose a message in Gmail and open it.

Create some labels

  1. Click the Labels button ( f04272c3ab0e04d6.png) from the Gmail menu bar above the email.

  2. Click Create new.

  3. Enter "Test 1" as your label name and click the Create button.

  4. Repeat these steps to create another label named "Test 2".

  5. Your installed add-ons appear in the right menu of the open email thread. Click on the ab2be82fe58f4252.pngicon that corresponds to the "Gmail Add-on Quickstart" you just installed.

  6. The add-on should place a contextual card on the right-side of the window, with a message asking for authorization. Click the Authorize access link to open a dialog where you can authorize the add-on.

  7. Select the student account that should authorize the add-on.

  8. If next dialog may informs you that the app is not verified:

  • Click Advanced.

  • At the bottom of the dialog, click Go to Gmail Add-on Quickstart (unsafe).

  • In the new dialog, type "Continue" into the text field, then click Next.

  1. Read the notice in the next dialog carefully, then click Allow.

  2. Once authorized, the add-on should automatically refresh and start operating.

Task 5. Use the add-on

  1. You should see that Test 1 and the Test 2 labels are checked under the Available User Labels section of the add-on.
  2. Click Test 2 checkbox to deselect the label. This will remove the label from that thread.
  3. Verify that the appropriate labels have been applied by navigating back to the inbox and observing that only the Test 1 label is still applied and Test 2 has been removed.
  4. Open a different email.
  5. Select Test 1 and Test 2 checkboxes enabling them both.
  6. Return to the inbox and observe that both labels have been applied to the email thread.
Create and use the Gmail Add-on


You now have an idea of what Gmail add-ons are capable of. You could do many other things like displaying other recent threads that the sender has started or translating the text of an email from one language to another without leaving Gmail.

Completion Badge

Finish your quest

This self-paced lab is part of the Qwiklabs Quest, Workspace Integrations. A Quest is a series of related labs that form a learning path.

Completing this Quest earns you the badge above, to recognize your achievement. You can make your badge (or badges) public and link to them in your online resume or social media account. Enroll in this Quest and get immediate completion credit if you’ve taken this lab. See other available Qwiklabs Quests.

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Manual Last Updated April 29, 2022
Lab Last Tested February 15, 2022

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