[AVRO-1664] PHP library can't serialise records with optional (union-null) values

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.7
• Fix Version/s: 1.10.0
• Component/s: php

Environment

php 5.5.15 OS X 10.9

• Assignee: Siad Ardroumli
• Reporter: Paul Banks
• Created: 24/Apr/15 19:49
• Updated: 02/Jul/20 12:22
• Resolved: 08/Jun/20 16:09

Description

PHP avro serialising doesn't appear to support "optional" fields in records.

Consider the PHP script below:

<?php

require_once('lib/avro.php');

$schema_json = <<<_JSON
{"name":"member",
 "type":"record",
 "fields":[{"name":"one", "type":"int"},
           {"name":"two", "type":["null", "string"]}
           ]}
_JSON;

$schema = AvroSchema::parse($schema_json);

// Our datum is missing the 'optional' field (i.e. it's null)
$datum = array("one" => 1);

$io = new AvroStringIO();
$writer = new AvroIODatumWriter($schema);
$encoder = new AvroIOBinaryEncoder($io);
$writer->write($datum, $encoder);
$bin = $io->string();

echo bin2hex($bin) . "\n";

My understanding from documentation is that this should work and output the encoded binary in hex.

Instead it throws:

PHP Fatal error:  Uncaught exception 'AvroIOTypeException' with message 'The datum array (
  'one' => 1,
) is not an example of schema {"type":"record","name":"member","fields":[{"name":"one","type":"int"},{"name":"two","type":["null","string"]}]}'

It's possible that this is not a valid usage of Avro and I'm mistaken in my expectations, so I tried the python library as a comparison. Sure enough the following script works as expected:

from avro import schema
from avro import io
from StringIO import StringIO

s = schema.parse("""
    {"name":"member",
    "type":"record",
    "fields":[{"name":"one", "type":"int"},
              {"name":"two", "type":["null", "string"]}
             ]}""")

writer = StringIO()
encoder = io.BinaryEncoder(writer)
datum_writer = io.DatumWriter(s)
datum_writer.write({"one": 1}, encoder)

print writer.getvalue().encode("hex")

which outputs:

$ python avro_test.py
0200

As expected.