learning/prompts/code-generation/java/09_io_avro.md

Prompt:
Write a sample Java code snippet that reads data from an Avro file using Apache Beam.

Response:
Your Apache Beam pipeline can read data from Apache Avro files using the AvroIO connector. Here is an example of how to achieve this:

```java
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericRecord;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.extensions.avro.AvroIO;
import org.apache.beam.sdk.options.Default;
import org.apache.beam.sdk.options.Description;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ReadGenericAvroIO {

    private static final Logger LOG = LoggerFactory.getLogger(ReadGenericAvroIO.class);

    // Define pipeline options for the pipeline
    public interface ReadAvroOptions extends PipelineOptions {
        @Description("Path to the Avro file to read from")
        @Default.String("gs://<your-bucket-name]/[your-object-name]/filename.avro")
        String getInput();

        void setInput(String value);
    }

    public static void main(String[] args) {

        // Create pipeline options to parse command-line arguments
        ReadAvroOptions options = PipelineOptionsFactory.fromArgs(args).withValidation().as(ReadAvroOptions.class);

        // Create a pipeline
        Pipeline p = Pipeline.create(options);

        // Declare the schema of the Avro file
        String fields = "[{ \"name\": \"months\", \"type\": \"string\" }, { \"name\": \"amount\", \"type\": \"string\" }]";
        String schema = "{\"type\": \"record\", \"name\": \"AvroRecord\",\"fields\":" + fields + "}";

        // Parse the schema string into a Schema object
        Schema avroSchema = new Schema.Parser().parse(schema);

        // Read the Avro file using the AvroIO connector
        p.apply(AvroIO.readGenericRecords(avroSchema).from(options.getInput()))
        // Parse the GenericRecord object into a string and log it
         .apply("Parse and log", ParDo.of(new DoFn<GenericRecord, String>() {
            @ProcessElement
            public void processElement(ProcessContext c) {
                GenericRecord record = c.element();
                String message = "Month: " + record.get("month") + ". Amount: " + record.get("amount");
                LOG.info(message);
                c.output(message);
            }
        }));

        // Execute the pipeline
        p.run();
    }
}
```

The `ReadAvroOptions` interface is used to define the command-line argument `--input`, which specifies the path to the Avro file. This code uses pipeline options to define the required argument.