[jira] [Created] (KAFKA-3134) Missing required configuration "value.deserializer" when initializing a KafkaConsumer with a valid "valueDeserializer"

[Yifan Ying (JIRA)]

Yifan Ying created KAFKA-3134:
---------------------------------

             Summary: Missing required configuration "value.deserializer" when 
initializing a KafkaConsumer with a valid "valueDeserializer"
                 Key: KAFKA-3134
                 URL: https://issues.apache.org/jira/browse/KAFKA-3134
             Project: Kafka
          Issue Type: Bug
    Affects Versions: 0.9.0.0
            Reporter: Yifan Ying


I tried to initialize a KafkaConsumer object using 

{code}
public KafkaConsumer(Properties properties, Deserializer<K> keyDeserializer,
                         Deserializer<V> valueDeserializer)
{code}

Then I got an exception as follows:
{code}
Caused by: org.apache.kafka.common.config.ConfigException: Missing required 
configuration "value.deserializer" which has no default value.
        at org.apache.kafka.common.config.ConfigDef.parse(ConfigDef.java:148)
        at 
org.apache.kafka.common.config.AbstractConfig.<init>(AbstractConfig.java:49)
        at 
org.apache.kafka.common.config.AbstractConfig.<init>(AbstractConfig.java:56)
        at 
org.apache.kafka.clients.consumer.ConsumerConfig.<init>(ConsumerConfig.java:336)
        at 
org.apache.kafka.clients.consumer.KafkaConsumer.<init>(KafkaConsumer.java:518)
        .....
{code}

Then I went ConsumerConfig.java file and found this block of code causing the 
problem:
{code}
public static Map<String, Object> addDeserializerToConfig(Map<String, Object> 
configs,
                                                              Deserializer<?> 
keyDeserializer,
                                                              Deserializer<?> 
valueDeserializer) {
        Map<String, Object> newConfigs = new HashMap<String, Object>();
        newConfigs.putAll(configs);
        if (keyDeserializer != null)
            newConfigs.put(KEY_DESERIALIZER_CLASS_CONFIG, 
keyDeserializer.getClass());
        if (keyDeserializer != null)
            newConfigs.put(VALUE_DESERIALIZER_CLASS_CONFIG, 
valueDeserializer.getClass());
        return newConfigs;
    }

    public static Properties addDeserializerToConfig(Properties properties,
                                                     Deserializer<?> 
keyDeserializer,
                                                     Deserializer<?> 
valueDeserializer) {
        Properties newProperties = new Properties();
        newProperties.putAll(properties);
        if (keyDeserializer != null)
            newProperties.put(KEY_DESERIALIZER_CLASS_CONFIG, 
keyDeserializer.getClass().getName());
        if (keyDeserializer != null)
            newProperties.put(VALUE_DESERIALIZER_CLASS_CONFIG, 
valueDeserializer.getClass().getName());
        return newProperties;
    }
{code}

Instead of checking valueDeserializer, the code checks keyDeserializer every 
time. So when keyDeserializer is null but valueDeserializer is not, the 
valueDeserializer property will never get set. 




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