在 avro 文件中存储空值

我有一些 json 数据，如下所示：

  {
    "id": 1998983092,
    "name": "Test Name 1",
    "type": "search string",
    "creationDate": "2017-06-06T13:49:15.091+0000",
    "lastModificationDate": "2017-06-28T14:53:19.698+0000",
    "lastModifiedUsername": "[email protected] /cdn-cgi/l/email-protection",
    "lockedQuery": false,
    "lockedByUsername": null
  }

我可以毫无问题地将lockedQuery null 值添加到GenericRecord 对象中。

GenericRecord record = new GenericData.Record(schema);
if(json.isNull("lockedQuery")){
    record.put("lockedQuery", null);
} 

但是，稍后当我尝试将该 GenericRecord 对象写入 avro 文件时，出现空指针异常。

File file = new File("~/test.arvo");
DatumWriter<GenericRecord> datumWriter = new GenericDatumWriter<>(schema);
DataFileWriter<GenericRecord> dataFileWriter = new DataFileWriter<>(datumWriter);
dataFileWriter.create(schema, file);
for(GenericRecord record: masterList) {
    dataFileWriter.append(record); // NULL POINTER HERE
}

当我运行该代码时，出现以下异常。非常感谢有关如何将空值处理到 Avro 文件中的任何提示。提前致谢。

java.lang.NullPointerException: null of boolean in field lockedQuery of 
com.mydomain.test1.domain.MyAvroRecord
Exception in thread "main" java.lang.RuntimeException: 
org.apache.avro.file.DataFileWriter$AppendWriteException: 
java.lang.NullPointerException: null of boolean in field lockedQuery of 
com.mydomain.test1.domain.MyAvroRecord
at com.mydomain.avro.App.main(App.java:198)
Caused by: org.apache.avro.file.DataFileWriter$AppendWriteException: 
java.lang.NullPointerException: null of boolean in field lockedQuery of 
com.mydomain.test1.domain.MyAvroRecord
at org.apache.avro.file.DataFileWriter.append(DataFileWriter.java:308)

编辑：这是 MyAvroRecord

public class MyAvroRecord {
    long id;
    String name;
    String type;
    Date timestamp;
    Date lastModifcationDate;
    String lastModifiedUsername;
    Boolean lockedQuery;

能够将 Avro 字段设置为null你应该在 Avro 模式中允许这样做，通过添加null作为该字段的可能类型之一。看一下 Avro 文档中的示例：

{
  "type": "record",
  "name": "MyRecord",
  "fields" : [
    {"name": "userId", "type": "long"},              // mandatory field
    {"name": "userName", "type": ["null", "string"]} // optional field 
  ]
}

here userName被声明为复合类型，可以是null or string。这种定义允许设置userName字段为空。作为对比userId只能包含长值，因此尝试设置userId为 null 将导致NullPointerException.