Create a Data Access Object for BigQuery Data using JDBI



A brief overview of creating a SQL Object API for BigQuery data in 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 BigQuery integrates connectivity to live BigQuery data in Java applications. By pairing these technologies, you gain simple, programmatic access to BigQuery data. This article walks through building a basic Data Access Object (DAO) and the accompanying code to read and write BigQuery data.

Create a DAO for the BigQuery 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 BigQuery @SqlUpdate("INSERT INTO Orders (ShipCity, Freight) values (:shipCity, :freight)") void insert(@Bind("shipCity") String shipCity, @Bind("freight") String freight); //request specific data from BigQuery (String type is used for simplicity) @SqlQuery("SELECT Freight FROM Orders WHERE ShipCity = :shipCity") String findFreightByShipCity(@Bind("shipCity") String shipCity); /* * close with no args is used to close the connection */ void close(); }

Open a Connection to BigQuery

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

Google uses the OAuth authentication standard. To access Google APIs on behalf of individual users, you can use the embedded credentials or you can register your own OAuth app.

OAuth also enables you to use a service account to connect on behalf of users in a Google Apps domain. To authenticate with a service account, you will need to register an application to obtain the OAuth JWT values.

In addition to the OAuth values, you will need to specify the DatasetId and ProjectId. See the "Getting Started" chapter of the help documentation for a guide to using OAuth.

Built-in Connection String Designer

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

java -jar cdata.jdbc.googlebigquery.jar

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

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

jdbc:googlebigquery:DataSetId=MyDataSetId;ProjectId=MyProjectId;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:googlebigquery:DataSetId=MyDataSetId;ProjectId=MyProjectId;InitiateOAuth=GETANDREFRESH"); MyOrdersDAO dao = dbi.open(MyOrdersDAO.class); //do stuff with the DAO dao.close();

Read BigQuery Data

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

//disply the result of our 'find' method String freight = dao.findFreightByShipCity("New York"); System.out.println(freight);

Write BigQuery Data

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

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

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

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