Preview links with smart chips

This page explains how to build a Google Workspace Add-on that lets Google Docs, Sheets, and Slides users preview links from a third-party service.

A Google Workspace Add-on can detect your service's links and prompt users to preview them. You can configure an add-on to preview multiple URL patterns, such as links to support cases, sales leads, and employee profiles.

How users preview links

To preview links, users interact with smart chips and cards.

When users type or paste a URL into a document or spreadsheet, Google Docs or Google Sheets prompts them to replace the link with a smart chip. The smart chip displays an icon and short title or description of the link's content. When the user hovers over the chip, they see a card interface that previews more information about the file or link.

The following video shows how a user converts a link into a smart chip and previews a card:

How users preview links in Slides

Third-party smart chips aren't supported for link previews in Slides. When users type or paste a URL into a presentation, Slides prompts them to replace the link with its title as linked text instead of a chip. When the user hovers over the link title, they see a card interface that previews information about the link.

The following image shows how a link preview renders in Slides:

Prerequisites

Apps Script

• A Google Workspace account.
• A Google Workspace Add-on. To build an add-on, follow this quickstart.

Node.js

• A Google Workspace account.
• A Google Workspace Add-on. To build an add-on, follow this quickstart.

Note: The Node.js code samples in this guide are written to run as a Cloud Function

Python

• A Google Workspace account.
• A Google Workspace Add-on. To build an add-on, follow this quickstart.

Note: The Python code samples in this guide are written to run as a Cloud Function using Python 3.9.

Java

• A Google Workspace account.
• A Google Workspace Add-on. To build an add-on, follow this quickstart.

Optional: Set up authentication to a third-party service

If your add-on connects to a service that requires authorization, users must authenticate to the service to preview links. This means that when users paste a link from your service into a Docs, Sheets, or Slides file for the first time, your add-on must invoke the authorization flow.

To set up an OAuth service or custom authorization prompt, see Connect your add-on to a third-party service.

Set up link previews for your add-on

This section explains how to set up link previews for your add-on, which includes the following steps:

1. Configure link previews in your add-on's manifest.
2. Build the smart chip and card interface for your links.

Configure link previews

To configure link previews, specify the following sections and fields in your add-on's manifest:

1. Under the addOns section, add the docs field to extend Docs, the sheets field to extend Sheets, and the slides field to extend Slides.

2. In each field, implement the linkPreviewTriggers trigger that includes a runFunction (You define this function in the following section, Build the smart chip and card).

   To learn about what fields you can specify in the linkPreviewTriggers trigger, see the reference documentation for Apps Script manifests or deployment resources for other runtimes.

3. In the oauthScopes field, add the scope https://www.googleapis.com/auth/workspace.linkpreview so that users can authorize the add-on to preview links on their behalf.

As an example, see the oauthScopes and addons section of the following manifest that configures link previews for a support case service.

Note: For Slides, labelText and localizedLabelText don't render, but you must include labelText for when Slides starts supporting third-party smart chips. localizedLabelText is optional.

{
  "oauthScopes": [
    "https://www.googleapis.com/auth/workspace.linkpreview"
  ],
  "addOns": {
    "common": {
      "name": "Preview support cases",
      "logoUrl": "https://www.example.com/images/company-logo.png",
      "layoutProperties": {
        "primaryColor": "#dd4b39"
      }
    },
    "docs": {
      "linkPreviewTriggers": [
        {
          "runFunction": "caseLinkPreview",
          "patterns": [
            {
              "hostPattern": "example.com",
              "pathPrefix": "support/cases"
            },
            {
              "hostPattern": "*.example.com",
              "pathPrefix": "cases"
            },
            {
              "hostPattern": "cases.example.com"
            }
          ],
          "labelText": "Support case",
          "logoUrl": "https://www.example.com/images/support-icon.png",
          "localizedLabelText": {
            "es": "Caso de soporte"
          }
        }
      ]
    },
    "sheets": {
      "linkPreviewTriggers": [
        {
          "runFunction": "caseLinkPreview",
          "patterns": [
            {
              "hostPattern": "example.com",
              "pathPrefix": "support/cases"
            },
            {
              "hostPattern": "*.example.com",
              "pathPrefix": "cases"
            },
            {
              "hostPattern": "cases.example.com"
            }
          ],
          "labelText": "Support case",
          "logoUrl": "https://www.example.com/images/support-icon.png",
          "localizedLabelText": {
            "es": "Caso de soporte"
          }
        }
      ]
    },
    "slides": {
      "linkPreviewTriggers": [
        {
          "runFunction": "caseLinkPreview",
          "patterns": [
            {
              "hostPattern": "example.com",
              "pathPrefix": "support/cases"
            },
            {
              "hostPattern": "*.example.com",
              "pathPrefix": "cases"
            },
            {
              "hostPattern": "cases.example.com"
            }
          ],
          "labelText": "Support case",
          "logoUrl": "https://www.example.com/images/support-icon.png",
          "localizedLabelText": {
            "es": "Caso de soporte"
          }
        }
      ]
    }
  }
}

In the example, the Google Workspace Add-on previews links for a company's support case service. The add-on specifies three URL patterns to preview links. Whenever a link matches one of the URL patterns, the callback function caseLinkPreview builds and displays a card and a smart chip in Docs, Sheets, or Slides, and replaces the URL with the link title.

Build the smart chip and card

To return a smart chip and card for a link, you must implement any functions that you specified in the linkPreviewTriggers object.

When a user interacts with a link that matches a specified URL pattern, the linkPreviewTriggers trigger fires and its callback function passes the event object EDITOR_NAME.matchedUrl.url as an argument. You use the payload of this event object to build the smart chip and card for your link preview.

For example, if a user previews the link https://www.example.com/cases/123456 in Docs, the following event payload is returned:

JSON

{
  "docs": {
    "matchedUrl": {
        "url": "https://www.example.com/support/cases/123456"
    }
  }
}

To create the card interface, you use widgets to display information about the link. You can also build actions that let users open the link or modify its contents. For a list of available widgets and actions, see Supported components for preview cards.

To build the smart chip and card for a link preview:

1. Implement the function that you specified in the linkPreviewTriggers section of your add-on's manifest:
   1. The function must accept an event object containing EDITOR_NAME.matchedUrl.url as an argument and return a single Card object.
   2. If your service requires authorization, the function must also invoke the authorization flow.
2. For each preview card, implement any callback functions that provide widget interactivity for the interface. For example, if you include a button that says "View link," you can create an action that specifies a callback function to open the link in a new window. To learn more about widget interactions, see Add-on actions.

Note: For link previews, the card response is cached for each user for 5 minutes. During that time, if a user previews a link, they receive the cached response. The cache is cleared when the user refreshes the file, or after 5 minutes. If the title of the returned card has changed, the app then prompts the user to refresh the title.

The following code creates the callback function caseLinkPreview for Docs:

Apps Script

apps-script/3p-resources/3p-resources.gs

View on GitHub

/**
* Entry point for a support case link preview.
*
* @param {!Object} event The event object.
* @return {!Card} The resulting preview link card.
*/
function caseLinkPreview(event) {

  // If the event object URL matches a specified pattern for support case links.
  if (event.docs.matchedUrl.url) {

    // Uses the event object to parse the URL and identify the case details.
    const caseDetails = parseQuery(event.docs.matchedUrl.url);

    // Builds a preview card with the case name, and description
    const caseHeader = CardService.newCardHeader()
      .setTitle(`Case ${caseDetails["name"][0]}`);
    const caseDescription = CardService.newTextParagraph()
      .setText(caseDetails["description"][0]);

    // Returns the card.
    // Uses the text from the card's header for the title of the smart chip.
    return CardService.newCardBuilder()
      .setHeader(caseHeader)
      .addSection(CardService.newCardSection().addWidget(caseDescription))
      .build();
  }
}

/**
* Extracts the URL parameters from the given URL.
*
* @param {!string} url The URL to parse.
* @return {!Map} A map with the extracted URL parameters.
*/
function parseQuery(url) {
  const query = url.split("?")[1];
  if (query) {
    return query.split("&")
    .reduce(function(o, e) {
      var temp = e.split("=");
      var key = temp[0].trim();
      var value = temp[1].trim();
      value = isNaN(value) ? value : Number(value);
      if (o[key]) {
        o[key].push(value);
      } else {
        o[key] = [value];
      }
      return o;
    }, {});
  }
  return null;
}

Node.js

node/3p-resources/index.js

View on GitHub

/**
 * 
 * A support case link preview.
 *
 * @param {!URL} url The event object.
 * @return {!Card} The resulting preview link card.
 */
function caseLinkPreview(url) {
  // Builds a preview card with the case name, and description
  // Uses the text from the card's header for the title of the smart chip.
  // Parses the URL and identify the case details.
  const name = `Case ${url.searchParams.get("name")}`;
  return {
    action: {
      linkPreview: {
        title: name,
        previewCard: {
          header: {
            title: name
          },
          sections: [{
            widgets: [{
              textParagraph: {
                text: url.searchParams.get("description")
              }
            }]
          }]
        }
      }
    }
  };
}

Python

python/3p-resources/create_link_preview/main.py

View on GitHub

def case_link_preview(url):
    """A support case link preview.
    Args:
      url: A matching URL.
    Returns:
      The resulting preview link card.
    """

    # Parses the URL and identify the case details.
    query_string = parse_qs(url.query)
    name = f'Case {query_string["name"][0]}'
    # Uses the text from the card's header for the title of the smart chip.
    return {
        "action": {
            "linkPreview": {
                "title": name,
                "previewCard": {
                    "header": {
                        "title": name
                    },
                    "sections": [{
                        "widgets": [{
                            "textParagraph": {
                                "text": query_string["description"][0]
                            }
                        }]
                    }],
                }
            }
        }
    }

Java

java/3p-resources/src/main/java/CreateLinkPreview.java

View on GitHub

/**
 * A support case link preview.
 *
 * @param url A matching URL.
 * @return The resulting preview link card.
 */
JsonObject caseLinkPreview(URL url) throws UnsupportedEncodingException {
  // Parses the URL and identify the case details.
  Map<String, String> caseDetails = new HashMap<String, String>();
  for (String pair : url.getQuery().split("&")) {
      caseDetails.put(URLDecoder.decode(pair.split("=")[0], "UTF-8"), URLDecoder.decode(pair.split("=")[1], "UTF-8"));
  }

  // Builds a preview card with the case name, and description
  // Uses the text from the card's header for the title of the smart chip.
  JsonObject cardHeader = new JsonObject();
  String caseName = String.format("Case %s", caseDetails.get("name"));
  cardHeader.add("title", new JsonPrimitive(caseName));

  JsonObject textParagraph = new JsonObject();
  textParagraph.add("text", new JsonPrimitive(caseDetails.get("description")));

  JsonObject widget = new JsonObject();
  widget.add("textParagraph", textParagraph);

  JsonArray widgets = new JsonArray();
  widgets.add(widget);

  JsonObject section = new JsonObject();
  section.add("widgets", widgets);

  JsonArray sections = new JsonArray();
  sections.add(section);

  JsonObject previewCard = new JsonObject();
  previewCard.add("header", cardHeader);
  previewCard.add("sections", sections);

  JsonObject linkPreview = new JsonObject();
  linkPreview.add("title", new JsonPrimitive(caseName));
  linkPreview.add("previewCard", previewCard);

  JsonObject action = new JsonObject();
  action.add("linkPreview", linkPreview);

  JsonObject renderActions = new JsonObject();
  renderActions.add("action", action);

  return renderActions;
}

Supported components for preview cards

Google Workspace Add-ons support the following widgets and actions for link preview cards:

Apps Script

Card Service field	Type
TextParagraph	Widget
DecoratedText	Widget
Image	Widget
IconImage	Widget
ButtonSet	Widget
TextButton	Widget
ImageButton	Widget
Grid	Widget
Divider	Widget
OpenLink	Action
Navigation	Action Only the updateCard method is supported.

JSON

Card (google.apps.card.v1) field	Type
TextParagraph	Widget
DecoratedText	Widget
Image	Widget
Icon	Widget
ButtonList	Widget
Button	Widget
Grid	Widget
Divider	Widget
OpenLink	Action
Navigation	Action Only the updateCard method is supported.

Complete example: Support case add-on

The following example features a Google Workspace Add-on that previews links to a company's support cases in Google Docs.

The example does the following:

• Previews links to support cases, such as https://www.example.com/support/cases/1234. The smart chip displays a support icon, and the preview card includes the case ID and a description.
• If the user's locale is set to Spanish, the smart chip localizes its labelText into Spanish.

Manifest

Apps Script

apps-script/3p-resources/appsscript.json

View on GitHub

{
  "timeZone": "America/New_York",
  "exceptionLogging": "STACKDRIVER",
  "runtimeVersion": "V8",
  "oauthScopes": [
    "https://www.googleapis.com/auth/workspace.linkpreview",
    "https://www.googleapis.com/auth/workspace.linkcreate"
  ],
  "addOns": {
    "common": {
      "name": "Manage support cases",
      "logoUrl": "https://developers.google.com/workspace/add-ons/images/support-icon.png",
      "layoutProperties": {
        "primaryColor": "#dd4b39"
      }
    },
    "docs": {
      "linkPreviewTriggers": [
        {
          "runFunction": "caseLinkPreview",
          "patterns": [
            {
              "hostPattern": "example.com",
              "pathPrefix": "support/cases"
            },
            {
              "hostPattern": "*.example.com",
              "pathPrefix": "cases"
            },
            {
              "hostPattern": "cases.example.com"
            }
          ],
          "labelText": "Support case",
          "localizedLabelText": {
            "es": "Caso de soporte"
          },
          "logoUrl": "https://developers.google.com/workspace/add-ons/images/support-icon.png"
        }
      ],
      "createActionTriggers": [
        {
          "id": "createCase",
          "labelText": "Create support case",
          "localizedLabelText": {
            "es": "Crear caso de soporte"
          },
          "runFunction": "createCaseInputCard",
          "logoUrl": "https://developers.google.com/workspace/add-ons/images/support-icon.png"
        }
      ]
    }
  }
}

JSON

Note: To use the following manifest, replace the URL value with the URL of the deployed function. You can deploy the function using the code sample.

{
  "oauthScopes": [
    "https://www.googleapis.com/auth/workspace.linkpreview"
  ],
  "addOns": {
    "common": {
      "name": "Preview support cases",
      "logoUrl": "https://developers.google.com/workspace/add-ons/images/support-icon.png",
      "layoutProperties": {
        "primaryColor": "#dd4b39"
      }
    },
    "docs": {
      "linkPreviewTriggers": [
        {
          "runFunction": "URL",
          "patterns": [
            {
              "hostPattern": "example.com",
              "pathPrefix": "support/cases"
            },
            {
              "hostPattern": "*.example.com",
              "pathPrefix": "cases"
            },
            {
              "hostPattern": "cases.example.com"
            }
          ],
          "labelText": "Support case",
          "localizedLabelText": {
            "es": "Caso de soporte"
          },
          "logoUrl": "https://developers.google.com/workspace/add-ons/images/support-icon.png"
        }
      ]
    }
  }
}

Code

Apps Script

apps-script/3p-resources/3p-resources.gs

View on GitHub

/**
* Entry point for a support case link preview.
*
* @param {!Object} event The event object.
* @return {!Card} The resulting preview link card.
*/
function caseLinkPreview(event) {

  // If the event object URL matches a specified pattern for support case links.
  if (event.docs.matchedUrl.url) {

    // Uses the event object to parse the URL and identify the case details.
    const caseDetails = parseQuery(event.docs.matchedUrl.url);

    // Builds a preview card with the case name, and description
    const caseHeader = CardService.newCardHeader()
      .setTitle(`Case ${caseDetails["name"][0]}`);
    const caseDescription = CardService.newTextParagraph()
      .setText(caseDetails["description"][0]);

    // Returns the card.
    // Uses the text from the card's header for the title of the smart chip.
    return CardService.newCardBuilder()
      .setHeader(caseHeader)
      .addSection(CardService.newCardSection().addWidget(caseDescription))
      .build();
  }
}

/**
* Extracts the URL parameters from the given URL.
*
* @param {!string} url The URL to parse.
* @return {!Map} A map with the extracted URL parameters.
*/
function parseQuery(url) {
  const query = url.split("?")[1];
  if (query) {
    return query.split("&")
    .reduce(function(o, e) {
      var temp = e.split("=");
      var key = temp[0].trim();
      var value = temp[1].trim();
      value = isNaN(value) ? value : Number(value);
      if (o[key]) {
        o[key].push(value);
      } else {
        o[key] = [value];
      }
      return o;
    }, {});
  }
  return null;
}

Node.js

node/3p-resources/index.js

View on GitHub

/**
 * Responds to any HTTP request related to link previews.
 *
 * @param {Object} req An HTTP request context.
 * @param {Object} res An HTTP response context.
 */
exports.createLinkPreview = (req, res) => {
  const event = req.body;
  if (event.docs.matchedUrl.url) {
    const url = event.docs.matchedUrl.url;
    const parsedUrl = new URL(url);
    // If the event object URL matches a specified pattern for preview links.
    if (parsedUrl.hostname === 'example.com') {
      if (parsedUrl.pathname.startsWith('/support/cases/')) {
        return res.json(caseLinkPreview(parsedUrl));
      }
    }
  }
};


/**
 * 
 * A support case link preview.
 *
 * @param {!URL} url The event object.
 * @return {!Card} The resulting preview link card.
 */
function caseLinkPreview(url) {
  // Builds a preview card with the case name, and description
  // Uses the text from the card's header for the title of the smart chip.
  // Parses the URL and identify the case details.
  const name = `Case ${url.searchParams.get("name")}`;
  return {
    action: {
      linkPreview: {
        title: name,
        previewCard: {
          header: {
            title: name
          },
          sections: [{
            widgets: [{
              textParagraph: {
                text: url.searchParams.get("description")
              }
            }]
          }]
        }
      }
    }
  };
}

Python

python/3p-resources/create_link_preview/main.py

View on GitHub

from typing import Any, Mapping
from urllib.parse import urlparse, parse_qs

import flask
import functions_framework


@functions_framework.http
def create_link_preview(req: flask.Request):
    """Responds to any HTTP request related to link previews.
    Args:
      req: An HTTP request context.
    Returns:
      An HTTP response context.
    """
    event = req.get_json(silent=True)
    if event["docs"]["matchedUrl"]["url"]:
        url = event["docs"]["matchedUrl"]["url"]
        parsed_url = urlparse(url)
        # If the event object URL matches a specified pattern for preview links.
        if parsed_url.hostname == "example.com":
            if parsed_url.path.startswith("/support/cases/"):
                return case_link_preview(parsed_url)

    return {}




def case_link_preview(url):
    """A support case link preview.
    Args:
      url: A matching URL.
    Returns:
      The resulting preview link card.
    """

    # Parses the URL and identify the case details.
    query_string = parse_qs(url.query)
    name = f'Case {query_string["name"][0]}'
    # Uses the text from the card's header for the title of the smart chip.
    return {
        "action": {
            "linkPreview": {
                "title": name,
                "previewCard": {
                    "header": {
                        "title": name
                    },
                    "sections": [{
                        "widgets": [{
                            "textParagraph": {
                                "text": query_string["description"][0]
                            }
                        }]
                    }],
                }
            }
        }
    }

Java

java/3p-resources/src/main/java/CreateLinkPreview.java

View on GitHub

import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonPrimitive;

import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.Map;

public class CreateLinkPreview implements HttpFunction {
  private static final Gson gson = new Gson();

  /**
   * Responds to any HTTP request related to link previews.
   *
   * @param request An HTTP request context.
   * @param response An HTTP response context.
   */
  @Override
  public void service(HttpRequest request, HttpResponse response) throws Exception {
    JsonObject event = gson.fromJson(request.getReader(), JsonObject.class);
    String url = event.getAsJsonObject("docs")
        .getAsJsonObject("matchedUrl")
        .get("url")
        .getAsString();
    URL parsedURL = new URL(url);
    // If the event object URL matches a specified pattern for preview links.
    if ("example.com".equals(parsedURL.getHost())) {
      if (parsedURL.getPath().startsWith("/support/cases/")) {
        response.getWriter().write(gson.toJson(caseLinkPreview(parsedURL)));
        return;
      }
    }

    response.getWriter().write("{}");
  }


  /**
   * A support case link preview.
   *
   * @param url A matching URL.
   * @return The resulting preview link card.
   */
  JsonObject caseLinkPreview(URL url) throws UnsupportedEncodingException {
    // Parses the URL and identify the case details.
    Map<String, String> caseDetails = new HashMap<String, String>();
    for (String pair : url.getQuery().split("&")) {
        caseDetails.put(URLDecoder.decode(pair.split("=")[0], "UTF-8"), URLDecoder.decode(pair.split("=")[1], "UTF-8"));
    }

    // Builds a preview card with the case name, and description
    // Uses the text from the card's header for the title of the smart chip.
    JsonObject cardHeader = new JsonObject();
    String caseName = String.format("Case %s", caseDetails.get("name"));
    cardHeader.add("title", new JsonPrimitive(caseName));

    JsonObject textParagraph = new JsonObject();
    textParagraph.add("text", new JsonPrimitive(caseDetails.get("description")));

    JsonObject widget = new JsonObject();
    widget.add("textParagraph", textParagraph);

    JsonArray widgets = new JsonArray();
    widgets.add(widget);

    JsonObject section = new JsonObject();
    section.add("widgets", widgets);

    JsonArray sections = new JsonArray();
    sections.add(section);

    JsonObject previewCard = new JsonObject();
    previewCard.add("header", cardHeader);
    previewCard.add("sections", sections);

    JsonObject linkPreview = new JsonObject();
    linkPreview.add("title", new JsonPrimitive(caseName));
    linkPreview.add("previewCard", previewCard);

    JsonObject action = new JsonObject();
    action.add("linkPreview", linkPreview);

    JsonObject renderActions = new JsonObject();
    renderActions.add("action", action);

    return renderActions;
  }

}

Related resources

• Preview links from Google Books with smart chips
• Test your add-on
• Google Docs manifest
• Card interfaces for link previews