Use Dash to Build to Web Apps on Stack Exchange Data

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

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

Connecting to Stack Exchange Data

Connecting to Stack Exchange 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.

Start by setting the Profile connection property to the location of the Stack Exchange Profile on disk (e.g. C:\profiles\StackExchange.apip). Next, set the ProfileSettings connection property to the connection string for Stack Exchange (see below).

Stack Exchange API Profile Settings

Register an application on StackApps to obtain an API Key. The Site property specifies which Stack Exchange site to query (e.g., stackoverflow).

After installing the CData Stack Exchange Connector, follow the procedure below to install the other required modules and start accessing Stack Exchange 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 Stack Exchange 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.api as mod
import plotly.graph_objs as go

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

cnxn = mod.connect("Profile=C:\profiles\StackExchange.apip;ProfileSettings='APIKey=your_api_key;Site=stackoverflow';")

Execute SQL to Stack Exchange

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 AnswerId, CreationDate FROM Answers WHERE IsAccepted = 'true'", 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-apiedataplot'

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 Stack Exchange data and configure the app layout.

trace = go.Bar(x=df.AnswerId, y=df.CreationDate, name='AnswerId')

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='Stack Exchange Answers 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 Stack Exchange data.

python api-dash.py

Free Trial & More Information

Download a free, 30-day trial of the CData API Driver for Python to start building Python apps with connectivity to Stack Exchange 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.api as mod
import plotly.graph_objs as go

cnxn = mod.connect("Profile=C:\profiles\StackExchange.apip;ProfileSettings='APIKey=your_api_key;Site=stackoverflow';")

df = pd.read_sql("SELECT AnswerId, CreationDate FROM Answers WHERE IsAccepted = 'true'", cnxn)
app_name = 'dash-apidataplot'

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.AnswerId, y=df.CreationDate, name='AnswerId')

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='Stack Exchange Answers Data', barmode='stack')
		})
], className="container")

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