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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright 2020 Confluent Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# A simple example demonstrating use of AvroDeserializer.
import argparse
import os
from confluent_kafka import Consumer
from confluent_kafka.serialization import SerializationContext, MessageField
from confluent_kafka.schema_registry import SchemaRegistryClient
from confluent_kafka.schema_registry.avro import AvroDeserializer
class User(object):
"""
User record
Args:
name (str): User's name
favorite_number (int): User's favorite number
favorite_color (str): User's favorite color
"""
def __init__(self, name=None, favorite_number=None, favorite_color=None):
self.name = name
self.favorite_number = favorite_number
self.favorite_color = favorite_color
def dict_to_user(obj, ctx):
"""
Converts object literal(dict) to a User instance.
Args:
obj (dict): Object literal(dict)
ctx (SerializationContext): Metadata pertaining to the serialization
operation.
"""
if obj is None:
return None
return User(name=obj['name'],
favorite_number=obj['favorite_number'],
favorite_color=obj['favorite_color'])
def main(args):
topic = args.topic
is_specific = args.specific == "true"
if is_specific:
schema = "user_specific.avsc"
else:
schema = "user_generic.avsc"
path = os.path.realpath(os.path.dirname(__file__))
with open(f"{path}/avro/{schema}") as f:
schema_str = f.read()
sr_conf = {'url': args.schema_registry}
schema_registry_client = SchemaRegistryClient(sr_conf)
avro_deserializer = AvroDeserializer(schema_registry_client,
schema_str,
dict_to_user)
consumer_conf = {'bootstrap.servers': args.bootstrap_servers,
'group.id': args.group,
'auto.offset.reset': "earliest"}
consumer = Consumer(consumer_conf)
consumer.subscribe([topic])
while True:
try:
# SIGINT can't be handled when polling, limit timeout to 1 second.
msg = consumer.poll(1.0)
if msg is None:
continue
user = avro_deserializer(msg.value(), SerializationContext(msg.topic(), MessageField.VALUE))
if user is not None:
print("User record {}: name: {}\n"
"\tfavorite_number: {}\n"
"\tfavorite_color: {}\n"
.format(msg.key(), user.name,
user.favorite_number,
user.favorite_color))
except KeyboardInterrupt:
break
consumer.close()
if __name__ == '__main__':
parser = argparse.ArgumentParser(description="AvroDeserializer example")
parser.add_argument('-b', dest="bootstrap_servers", required=True,
help="Bootstrap broker(s) (host[:port])")
parser.add_argument('-s', dest="schema_registry", required=True,
help="Schema Registry (http(s)://host[:port]")
parser.add_argument('-t', dest="topic", default="example_serde_avro",
help="Topic name")
parser.add_argument('-g', dest="group", default="example_serde_avro",
help="Consumer group")
parser.add_argument('-p', dest="specific", default="true",
help="Avro specific record")
main(parser.parse_args())
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