Create a Data Access Object for Lakebase Data using JDBI

JDBI is a SQL convenience library for Java that exposes two different style APIs, a fluent style and a SQL object style. The CData JDBC Driver for Lakebase integrates connectivity to live Lakebase data in Java applications. By pairing these technologies, you gain simple, programmatic access to Lakebase data. This article walks through building a basic Data Access Object (DAO) and the accompanying code to read and write Lakebase data.

Create a DAO for the Lakebase Orders Entity

The interface below declares the desired behavior for the SQL object to create a single method for each SQL statement to be implemented.

public interface MyOrdersDAO {
  //insert new data into Lakebase
  @SqlUpdate("INSERT INTO Orders (ShipCountry, ShipCity) values (:shipCountry, :shipCity)")
  void insert(@Bind("shipCountry") String shipCountry, @Bind("shipCity") String shipCity);

  //request specific data from Lakebase (String type is used for simplicity)
  @SqlQuery("SELECT ShipCity FROM Orders WHERE ShipCountry = :shipCountry")
  String findShipCityByShipCountry(@Bind("shipCountry") String shipCountry);

  /*
   * close with no args is used to close the connection
   */
  void close();
}

Open a Connection to Lakebase

Collect the necessary connection properties and construct the appropriate JDBC URL for connecting to Lakebase.

• DatabricksInstance: The Databricks instance or server hostname, provided in the format instance-abcdef12-3456-7890-abcd-abcdef123456.database.cloud.databricks.com.
• Server: The host name or IP address of the server hosting the Lakebase database.
• Port (optional): The port of the server hosting the Lakebase database, set to 5432 by default.
• Database (optional): The database to connect to after authenticating to the Lakebase Server, set to the authenticating user's default database by default.

OAuth Client Authentication

To authenicate using OAuth client credentials, you need to configure an OAuth client in your service principal. In short, you need to do the following:

1. Create and configure a new service principal
2. Assign permissions to the service principal
3. Create an OAuth secret for the service principal

For more information, refer to the Setting Up OAuthClient Authentication section in the Help documentation.

OAuth PKCE Authentication

To authenticate using the OAuth code type with PKCE (Proof Key for Code Exchange), set the following properties:

• AuthScheme: OAuthPKCE.
• User: The authenticating user's user ID.

For more information, refer to the Help documentation.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the Lakebase JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.lakebase.jar

Fill in the connection properties and copy the connection string to the clipboard.

A connection string for Lakebase will typically look like the following:

jdbc:lakebase:DatabricksInstance=lakebase;Server=127.0.0.1;Port=5432;Database=my_database;InitiateOAuth=GETANDREFRESH;

Use the configured JDBC URL to obtain an instance of the DAO interface. The particular method shown below will open a handle bound to the instance, so the instance needs to be closed explicitly to release the handle and the bound JDBC connection.

DBI dbi = new DBI("jdbc:lakebase:DatabricksInstance=lakebase;Server=127.0.0.1;Port=5432;Database=my_database;InitiateOAuth=GETANDREFRESH;");
MyOrdersDAO dao = dbi.open(MyOrdersDAO.class);

//do stuff with the DAO

dao.close();

Read Lakebase Data

With the connection open to Lakebase, simply call the previously defined method to retrieve data from the Orders entity in Lakebase.

//disply the result of our 'find' method
String shipCity = dao.findShipCityByShipCountry("USA");
System.out.println(shipCity);

Write Lakebase Data

It is also simple to write data to Lakebase, using the previously defined method.

//add a new entry to the Orders entity
dao.insert(newShipCountry, newShipCity);

Since the JDBI library is able to work with JDBC connections, you can easily produce a SQL Object API for Lakebase by integrating with the CData JDBC Driver for Lakebase. Download a free trial and work with live Lakebase data in custom Java applications today.