/**
* Get a map of field names to default values for an Avro schema.
*
* @param avroRecordSchema The schema to get the map of field names to values.
* @return The map.
*/
public static Map<String, Object> getDefaultValueMap(Schema avroRecordSchema) {
List<Field> defaultFields = new ArrayList<Field>();
for (Field f : avroRecordSchema.getFields()) {
if (f.defaultValue() != null) {
// Need to create a new Field here or we will get
// org.apache.avro.AvroRuntimeException: Field already used:
// schemaVersion
defaultFields.add(new Field(f.name(), f.schema(), f.doc(), f.defaultValue(), f.order()));
}
}
Schema defaultSchema = Schema.createRecord(defaultFields);
Schema emptyRecordSchema = Schema.createRecord(new ArrayList<Field>());
DatumWriter<GenericRecord> writer = new GenericDatumWriter<GenericRecord>(emptyRecordSchema);
DatumReader<GenericRecord> reader =
new GenericDatumReader<GenericRecord>(emptyRecordSchema, defaultSchema);
GenericRecord emptyRecord = new GenericData.Record(emptyRecordSchema);
GenericRecord defaultRecord =
AvroUtils.readAvroEntity(AvroUtils.writeAvroEntity(emptyRecord, writer), reader);
Map<String, Object> defaultValueMap = new HashMap<String, Object>();
for (Field f : defaultFields) {
defaultValueMap.put(f.name(), defaultRecord.get(f.name()));
}
return defaultValueMap;
}
/**
* Given an avro Schema.Field instance, make a clone of it.
*
* @param field The field to clone.
* @return The cloned field.
*/
public static Field cloneField(Field field) {
return new Field(field.name(), field.schema(), field.doc(), field.defaultValue());
}