I'm looking for a way to convert a POJO to an avro object in a generic way. The implementation should be robust to any changes of the POJO-class. I have achieved it but filling the avro record explicitly (see example below).
Is there a way to get rid of the hard-coded field names and just fill the avro record from the object? Is reflection the only way, or does avro provide this functionality out of the box?
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData.Record;
import org.apache.avro.reflect.ReflectData;
public class PojoToAvroExample {
static class PojoParent {
public final Map<String, String> aMap = new HashMap<String, String>();
public final Map<String, Integer> anotherMap = new HashMap<String, Integer>();
}
static class Pojo extends PojoParent {
public String uid;
public Date eventTime;
}
static Pojo createPojo() {
Pojo foo = new Pojo();
foo.uid = "123";
foo.eventTime = new Date();
foo.aMap.put("key", "val");
foo.anotherMap.put("key", 42);
return foo;
}
public static void main(String[] args) {
// extract the avro schema corresponding to Pojo class
Schema schema = ReflectData.get().getSchema(Pojo.class);
System.out.println("extracted avro schema: " + schema);
// create avro record corresponding to schema
Record avroRecord = new Record(schema);
System.out.println("corresponding empty avro record: " + avroRecord);
Pojo foo = createPojo();
// TODO: to be replaced by generic variant:
// something like avroRecord.importValuesFrom(foo);
avroRecord.put("uid", foo.uid);
avroRecord.put("eventTime", foo.eventTime);
avroRecord.put("aMap", foo.aMap);
avroRecord.put("anotherMap", foo.anotherMap);
System.out.println("expected avro record: " + avroRecord);
}
}