How to use SQLAlchemy ORM to access SAP Netweaver Gateway Data in Python

Create Python applications and scripts that use SQLAlchemy Object-Relational Mappings of SAP Netweaver Gateway data.

The rich ecosystem of Python modules lets you get to work quickly and integrate your systems effectively. With the CData Python Connector for SAP Netweaver Gateway and the SQLAlchemy toolkit, you can build SAP Netweaver Gateway-connected Python applications and scripts. This article shows how to use SQLAlchemy to connect to SAP Netweaver Gateway data to query, update, delete, and insert SAP Netweaver Gateway data.

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

Connecting to SAP Netweaver Gateway Data

Connecting to SAP Netweaver Gateway 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.

SAP Gateway allows both basic and OAuth 2.0 authentication. You can use basic authentication to connect to your own account, or you can use OAuth to enable other users to retrieve data from your service with their accounts. In addition to authenticating, set the following connection properties to access SAP Gateway tables.

Url: Set this to the URL of your environment, or to the full URL of the service. For example, the full URL might appear as: https://sapes5.sapdevcenter.com/sap/opu/odata/IWBEP/GWSAMPLE_BASIC/. In this example, the environment URL would just be: https://sapes5.sapdevcenter.com.
Namespace: Set the appropriate Service Namespace. In the example above, IWBEP is the namespace. It is optional if the full URL to the service is specified.
Service: Set this to the service you want to retrieve data from. In the example above, the service is GWSAMPLE_BASIC. It is not required if the full URL is specified.

Authenticate via Basic Authentication

In basic authentication, you use your login credentials to connect. Set the following properties:

User: This is the username you use to log in to SAP Gateway.
Password: This is the password you use to log in to SAP Gateway.

Authenticate via OAuth Authentication

You can connect to SAP Gateway using the embedded OAuth connectivity (without setting any additional authentication connection properties). When you connect, the OAuth endpoint opens in your browser. Log in and grant permissions to complete the OAuth process. See the OAuth section in the online Help documentation for more information on other OAuth authentication flows.

Follow the procedure below to install SQLAlchemy and start accessing SAP Netweaver Gateway 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 SAP Netweaver Gateway Data in Python

You can now connect with a connection string. Use the create_engine function to create an Engine for working with SAP Netweaver Gateway 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("sapgateway:///?User=user&Password=password&URL=https://sapes5.sapdevcenter.com/sap/opu/odata/IWBEP/GWSAMPLE_BASIC/&InitiateOAuth=GETANDREFRESH&OAuthSettingsLocation=/PATH/TO/OAuthSettings.txt")

Declare a Mapping Class for SAP Netweaver Gateway 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 SalesOrderLineItems 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 SalesOrderLineItems(base):
	__tablename__ = "SalesOrderLineItems"
	ProductID = Column(String,primary_key=True)
	Quantity = Column(String)
	...

Query SAP Netweaver Gateway 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("sapgateway:///?User=user&Password=password&URL=https://sapes5.sapdevcenter.com/sap/opu/odata/IWBEP/GWSAMPLE_BASIC/&InitiateOAuth=GETANDREFRESH&OAuthSettingsLocation=/PATH/TO/OAuthSettings.txt")
factory = sessionmaker(bind=engine)
session = factory()
for instance in session.query(SalesOrderLineItems).filter_by(Quantity="15"):
	print("ProductID: ", instance.ProductID)
	print("Quantity: ", instance.Quantity)
	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


SalesOrderLineItems_table = SalesOrderLineItems.metadata.tables["SalesOrderLineItems"]
for instance in session.execute(SalesOrderLineItems_table.select().where(SalesOrderLineItems_table.c.Quantity == "15")):
	print("ProductID: ", instance.ProductID)
	print("Quantity: ", instance.Quantity)
	print("---------")

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

Insert SAP Netweaver Gateway Data

To insert SAP Netweaver Gateway data, define an instance of the mapped class and add it to the active session. Call the commit function on the session to push all added instances to SAP Netweaver Gateway.


new_rec = SalesOrderLineItems(ProductID="placeholder", Quantity="15")
session.add(new_rec)
session.commit()

Update SAP Netweaver Gateway Data

To update SAP Netweaver Gateway data, fetch the desired record(s) with a filter query. Then, modify the values of the fields and call the commit function on the session to push the modified record to SAP Netweaver Gateway.


updated_rec = session.query(SalesOrderLineItems).filter_by(SOME_ID_COLUMN="SOME_ID_VALUE").first()
updated_rec.Quantity = "15"
session.commit()

Delete SAP Netweaver Gateway Data

To delete SAP Netweaver Gateway data, fetch the desired record(s) with a filter query. Then delete the record with the active session and call the commit function on the session to perform the delete operation on the provided records (rows).


deleted_rec = session.query(SalesOrderLineItems).filter_by(SOME_ID_COLUMN="SOME_ID_VALUE").first()
session.delete(deleted_rec)
session.commit()

Free Trial & More Information

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