Getting Started

Let’s build a simple Tableau extension that displays the summary data from Tableau when a user clicks a bar in a bar chart.

First create a new Tableau extension in Anvil by selecting “Blank app” and then “Tableau Extension”:

https://extension-documentation.s3.amazonaws.com/media/blank_app.PNG https://extension-documentation.s3.amazonaws.com/media/tableau_extension.PNG

Download and add a trex file to Tableau

In order to add an extension built in Anvil to Tableau it needs to be added to the dashboard using a .trex file. The trex file is first downloaded from Anvil and then dropped in to your Tableau dashboard.

In Anvil:

  1. Click the green “Test in Tableau” button in the top right.

  2. A popup will appear, click “Click here to download the manifest file for your extension”, the trex file should appear in your downloads.

In Tableau:

  1. Go to the dashboard, drag and drop the “Extension” object wherever you’d like.

  2. In the bottom left of the alert that appears, select “Access Local Extensions” and locate the .trex file from step 2.

https://extension-documentation.s3.amazonaws.com/media/download_trex.gif

Write some code

Now that we’re connected to our dashboard let’s add some components and code.

  • Rename Form1 to MainForm

  • Add a label to the UI and change its Python name to label_1

  • Paste the following in the code section of the MainForm

 1# client_code/MainForm
 2from ._anvil_designer import MainFormTemplate
 3from anvil import *
 4from trexjacket.api import get_dashboard
 5
 6class MainForm(MainFormTemplate):
 7    def __init__(self, **properties):
 8        self.init_components(**properties)
 9        self.dashboard = get_dashboard() # we now have a Python object that represents our dashboard!!
10        self.dashboard.register_event_handler('selection_changed', self.show_selections)
11
12    def show_selections(self, event):
13        print(event.worksheet.selected_records)
14        self.label_1.text = str(event.worksheet.get_selected_marks())

In the form code above, we do 2 important things:

  1. Get the current Tableau dashboard using get_dashboard. This returns a Dashboard object and contains many useful attributes and methods such as datasources, filters, parameters, and worksheets.

  2. Bind the show_selections method of our Anvil form to the selection_changed event of the Tableau dashboard using register_event_handler. The selection_changed event triggers show_selections whenever the user selects / unselects marks.

Congrats, you now have a working Tableau extension!
https://extension-documentation.s3.amazonaws.com/media/firstexample.gif

Additionally, output from the print statement appears in the Anvil IDE:

https://extension-documentation.s3.amazonaws.com/media/output_in_anvil.PNG

Download the resources!

Click here to clone the Anvil App

Click here to download the Tableau workbook