Create a Data Access Object for Alchemy 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 Alchemy integrates connectivity to live Alchemy data in Java applications. By pairing these technologies, you gain simple, programmatic access to Alchemy data. This article explains how to build a basic Data Access Object (DAO) and the accompanying code to read Alchemy data.

Create a DAO for the Alchemy ContractsForOwner 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 MyContractsForOwnerDAO {
  //request specific data from Alchemy (String type is used for simplicity)
  @SqlQuery("SELECT Name FROM ContractsForOwner WHERE Owner = :owner")
  String findNameByOwner(@Bind("owner") String owner);

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

Open a Connection to Alchemy

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

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

Alchemy API Profile Settings

Alchemy uses API key authentication. The API key is supplied in the request URL path. To obtain an API key:

1. Sign in to your Alchemy account at https://dashboard.alchemy.com.
2. Open an existing app or create a new one.
3. Copy the app's API key from the API Key dialog.

After obtaining your API key, set the following connection properties:

• AuthScheme: Set this to APIKey.
• Network: Optional. The blockchain network slug for NFT API requests (for example, eth-mainnet, base-mainnet, polygon-mainnet). Defaults to eth-mainnet.

Set the following in the ProfileSettings connection property:

• APIKey: Set this to your Alchemy app API key.

Built-in Connection String Designer

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

java -jar cdata.jdbc.api.jar

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

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

jdbc:api:Profile=C:\profiles\Alchemy.apip;AuthScheme=APIKey;Network=eth-mainnet;ProfileSettings='APIKey=your_api_key';

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:api:Profile=C:\profiles\Alchemy.apip;AuthScheme=APIKey;Network=eth-mainnet;ProfileSettings='APIKey=your_api_key';");
MyContractsForOwnerDAO dao = dbi.open(MyContractsForOwnerDAO.class);

//do stuff with the DAO

dao.close();

Read Alchemy Data

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

//disply the result of our 'find' method
String name = dao.findNameByOwner("0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045");
System.out.println(name);

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