[jira] [Created] (NIFI-6204) Avro with a default field of type long fails with ClassCastException

["Lars Francke (JIRA)" <ji...@apache.org>]

Lars Francke created NIFI-6204:
----------------------------------

             Summary: Avro with a default field of type long fails with ClassCastException
                 Key: NIFI-6204
                 URL: https://issues.apache.org/jira/browse/NIFI-6204
             Project: Apache NiFi
          Issue Type: Bug
            Reporter: Lars Francke
         Attachments: Avro-issue.xml, Screen Shot 2019-04-11 at 00.33.51.png, Screen Shot 2019-04-11 at 00.38.31.png

I get this error:
{code}org.apache.avro.file.DataFileWriter$AppendWriteException: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Long{code}

I've attached an example workflow plus screenshots.

Basically: Converting a schema like this

{code}
{
 "name": "foobar",
 "type": "record",
 "fields": [
   { "name": "a", "type": "string" }
 ]
}
{code}

into this
{code}
{
 "name": "foobar",
 "type": "record",
 "fields": [
   { "name": "a", "type": "string" },
   { "name": "b", "type": "long", "default": 100 }
 ]
}
{code}

fails because of this snippet in {{AvroTypeUtil}}:
{code}
        // see if the Avro schema has any fields that aren't in the RecordSchema, and if those fields have a default
        // value then we want to populate it in the GenericRecord being produced
        for (final Field field : avroSchema.getFields()) {
            final Optional<RecordField> recordField = recordSchema.getField(field.name());
            if (!recordField.isPresent() && rec.get(field.name()) == null && field.defaultVal() != null) {
                rec.put(field.name(), field.defaultVal());
            }
        }
{code}

This relies on {{field.defaultVal()}} returning the correct type.
The field that this relies on is a {{JsonNode}} from Jackson. So it parses the Schema and the "default" field is parsed into an {{IntNode}} which is then put into the record and that is not a Long so the cast fails when Avro tries to write it later.

Now Jackson has no way of knowing that this is supposed to be a LongNode instead of an IntNode. I'm not sure if Avro should catch this or NiFi and I also have no good idea on how to fix this.



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