Matt Grimwade created AVRO-1678:
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Summary: JSON encoding of empty record should be "{}"
Key: AVRO-1678
URL: https://issues.apache.org/jira/browse/AVRO-1678
Project: Avro
Issue Type: Bug
Components: java
Affects Versions: 1.7.7
Reporter: Matt Grimwade
An empty record (i.e. an instance of a record schema with no fields) should be
encoded in JSON as {{"{}"}}. (This is my interpretation of [the
spec|https://avro.apache.org/docs/1.7.7/spec.html#schema_record], which states
only that records are encoded as JSON objects.)
However as of Avro 1.7.7, the Java implementation yields {{""}}. This is the
case for both generic and specific datum writers. Here is a failing test case
(using generic):
{code}
@Test
public void testThis() throws Exception {
Schema emptyRecordSchema = new
Schema.Parser().parse("{\"type\":\"record\",\"name\":\"EmptyRecord\",\"fields\":[]}");
Schema arraySchema = Schema.createArray(emptyRecordSchema);
GenericRecord emptyRecord = (GenericRecord)
GenericData.get().newRecord(null, emptyRecordSchema);
GenericArray<GenericRecord> emptyArray = new
GenericData.Array<>(arraySchema, Collections.<GenericRecord>emptyList());
GenericArray<GenericRecord> arrayContainingEmptyRecord = new
GenericData.Array<>(arraySchema, Arrays.asList(emptyRecord));
Assert.assertThat(toJson(emptyArray), Matchers.is("[]")); // OK
Assert.assertThat(toJson(arrayContainingEmptyRecord), Matchers.is("[{}]"));
// OK
Assert.assertThat(toJson(emptyRecord), Matchers.is("{}")); // fail: json is
""
}
private static String toJson(GenericContainer record) throws IOException {
Schema schema = record.getSchema();
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
ParsingEncoder encoder = EncoderFactory.get().jsonEncoder(schema, buffer);
@SuppressWarnings("unchecked") DatumWriter<GenericContainer> writer =
GenericData.get().createDatumWriter(schema);
writer.write(record, encoder);
encoder.flush();
return new String(buffer.toByteArray(), StandardCharsets.UTF_8);
}
{code}
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