Use Dash to Build to Web Apps on Excel Online Data

The rich ecosystem of Python modules lets you get to work quickly and integrate your systems more effectively. With the CData Python Connector for Excel Online, the pandas module, and the Dash framework, you can build Excel Online-connected web applications for Excel Online data. This article shows how to connect to Excel Online with the CData Connector and use pandas and Dash to build a simple web app for visualizing Excel Online data.

With built-in, optimized data processing, the CData Python Connector offers unmatched performance for interacting with live Excel Online data in Python. When you issue complex SQL queries from Excel Online, the driver pushes supported SQL operations, like filters and aggregations, directly to Excel Online and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations).

Connecting to Excel Online Data

Connecting to Excel Online data looks just like connecting to any relational data source. Create a connection string using the required connection properties. For this article, you will pass the connection string as a parameter to the create_engine function.

You can connect to a workbook by providing authentication to Excel Online and then setting the following properties:

• Workbook: Set this to the name or Id of the workbook.

  If you want to view a list of information about the available workbooks, execute a query to the Workbooks view after you authenticate.

• UseSandbox: Set this to true if you are connecting to a workbook in a sandbox account. Otherwise, leave this blank to connect to a production account.

You use the OAuth authentication standard to authenticate to Excel Online. See the Getting Started section in the help documentation for a guide. Getting Started also guides you through executing SQL to worksheets and ranges.

After installing the CData Excel Online Connector, follow the procedure below to install the other required modules and start accessing Excel Online through Python objects.

Install Required Modules

Use the pip utility to install the required modules and frameworks:

pip install pandas
pip install dash
pip install dash-daq

Visualize Excel Online Data in Python

Once the required modules and frameworks are installed, we are ready to build our web app. Code snippets follow, but the full source code is available at the end of the article.

First, be sure to import the modules (including the CData Connector) with the following:

import os
import dash
import dash_core_components as dcc
import dash_html_components as html
import pandas as pd
import cdata.excelonline as mod
import plotly.graph_objs as go

You can now connect with a connection string. Use the connect function for the CData Excel Online Connector to create a connection for working with Excel Online data.

cnxn = mod.connect("InitiateOAuth=GETANDREFRESH;OAuthSettingsLocation=/PATH/TO/OAuthSettings.txt")")

Execute SQL to Excel Online

Use the read_sql function from pandas to execute any SQL statement and store the result set in a DataFrame.

df = pd.read_sql("SELECT Id, Column1 FROM Test_xlsx_Sheet1 WHERE Column2 = 'Bob'", cnxn)

Configure the Web App

With the query results stored in a DataFrame, we can begin configuring the web app, assigning a name, stylesheet, and title.

app_name = 'dash-excelonlineedataplot'

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
app.title = 'CData + Dash'

Configure the Layout

The next step is to create a bar graph based on our Excel Online data and configure the app layout.

trace = go.Bar(x=df.Id, y=df.Column1, name='Id')

app.layout = html.Div(children=[html.H1("CData Extension + Dash", style={'textAlign': 'center'}),
	dcc.Graph(
		id='example-graph',
		figure={
			'data': [trace],
			'layout':
			go.Layout(title='Excel Online Test_xlsx_Sheet1 Data', barmode='stack')
		})
], className="container")

Set the App to Run

With the connection, app, and layout configured, we are ready to run the app. The last lines of Python code follow.

if __name__ == '__main__':
    app.run_server(debug=True)

Now, use Python to run the web app and a browser to view the Excel Online data.

python excelonline-dash.py

Free Trial & More Information

Download a free, 30-day trial of the CData Python Connector for Excel Online to start building Python apps with connectivity to Excel Online data. Reach out to our Support Team if you have any questions.

Full Source Code

import os
import dash
import dash_core_components as dcc
import dash_html_components as html
import pandas as pd
import cdata.excelonline as mod
import plotly.graph_objs as go

cnxn = mod.connect("InitiateOAuth=GETANDREFRESH;OAuthSettingsLocation=/PATH/TO/OAuthSettings.txt")

df = pd.read_sql("SELECT Id, Column1 FROM Test_xlsx_Sheet1 WHERE Column2 = 'Bob'", cnxn)
app_name = 'dash-excelonlinedataplot'

external_stylesheets = ['https://codepen.io/chriddyp/pen/bWLwgP.css']

app = dash.Dash(__name__, external_stylesheets=external_stylesheets)
app.title = 'CData + Dash'
trace = go.Bar(x=df.Id, y=df.Column1, name='Id')

app.layout = html.Div(children=[html.H1("CData Extension + Dash", style={'textAlign': 'center'}),
	dcc.Graph(
		id='example-graph',
		figure={
			'data': [trace],
			'layout':
			go.Layout(title='Excel Online Test_xlsx_Sheet1 Data', barmode='stack')
		})
], className="container")

if __name__ == '__main__':
    app.run_server(debug=True)