How to use SQLAlchemy ORM to access Databox Data in Python

The rich ecosystem of Python modules lets you get to work quickly and integrate your systems effectively. With the CData API Driver for Python and the SQLAlchemy toolkit, you can build Databox-connected Python applications and scripts. This article shows how to use SQLAlchemy to connect to Databox data to query Databox data.

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

Connecting to Databox Data

Connecting to Databox 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 Databox Profile on disk (e.g. C:\profiles\Databox.apip). Next, set the ProfileSettings connection property to the connection string for Databox (see below).

Databox API Profile Settings

To use the Databox API, you need to generate a personal access key from your Databox account. Navigate to the Databox account settings under Data Manager and generate an API key (prefixed with pak_).

After setting the following connection properties, you are ready to connect:

• AuthScheme: Set this to APIKey.
• APIKey: Set this to your Databox personal access key.

Follow the procedure below to install SQLAlchemy and start accessing Databox through Python objects.

Install Required Modules

Use the pip utility to install the SQLAlchemy toolkit and SQLAlchemy ORM package:

pip install sqlalchemy
pip install sqlalchemy.orm

Be sure to import the appropriate modules:

from sqlalchemy import create_engine, String, Column
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

Model Databox Data in Python

You can now connect with a connection string. Use the create_engine function to create an Engine for working with Databox data.

NOTE: Users should URL encode the any connection string properties that include special characters. For more information, refer to the SQL Alchemy documentation.

engine = create_engine("api:///?Profile=C:\profiles\Databox.apip&AuthScheme=APIKey&ProfileSettings='APIKey=your_api_key'")

Declare a Mapping Class for Databox Data

After establishing the connection, declare a mapping class for the table you wish to model in the ORM (in this article, we will model the Datasets table). Use the sqlalchemy.ext.declarative.declarative_base function and create a new class with some or all of the fields (columns) defined.

base = declarative_base()
class Datasets(base):
	__tablename__ = "Datasets"
	Id = Column(String,primary_key=True)
	Title = Column(String)
	...

Query Databox Data

With the mapping class prepared, you can use a session object to query the data source. After binding the Engine to the session, provide the mapping class to the session query method.

Using the query Method

engine = create_engine("api:///?Profile=C:\profiles\Databox.apip&AuthScheme=APIKey&ProfileSettings='APIKey=your_api_key'")
factory = sessionmaker(bind=engine)
session = factory()
for instance in session.query(Datasets).filter_by(DataSourceId="4976164"):
	print("Id: ", instance.Id)
	print("Title: ", instance.Title)
	print("---------")

Alternatively, you can use the execute method with the appropriate table object. The code below works with an active session.

Using the execute Method

Datasets_table = Datasets.metadata.tables["Datasets"]
for instance in session.execute(Datasets_table.select().where(Datasets_table.c.DataSourceId == "4976164")):
	print("Id: ", instance.Id)
	print("Title: ", instance.Title)
	print("---------")

For examples of more complex querying, including JOINs, aggregations, limits, and more, refer to the Help documentation for the extension.

Free Trial & More Information

Download a free, 30-day trial of the CData API Driver for Python to start building Python apps and scripts with connectivity to Databox data. Reach out to our Support Team if you have any questions.