Kevin Burke created AVRO-4225:
---------------------------------
Summary: GenericDatumReader throws ClassCastException for schemas
with "java-class" attribute on string fields
Key: AVRO-4225
URL: https://issues.apache.org/jira/browse/AVRO-4225
Project: Apache Avro
Issue Type: Bug
Affects Versions: 1.12.1
Reporter: Kevin Burke
A minimal reproduction test case can be found here:
https://github.com/apache/avro/pull/3616
When deserializing records using {{GenericDatumReader}} with schemas that have
a {{"java-class"}} attribute on string fields (e.g., {{{}"java-class":
"java.math.BigDecimal"{}}}), Avro throws a {{{}ClassCastException{}}}.
*Schema example:*
{{{
"type": "record",
"name": "TestRecord",
"fields": [
\{"name": "price", "type": ["null", {
"type": "string",
"java-class": "java.math.BigDecimal"
}]}
]
}}}
*Stack trace:*
{{java.lang.ClassCastException: class org.apache.avro.util.Utf8 cannot be cast
to class java.lang.String
at
org.apache.avro.io.FastReaderBuilder.lambda$getTransformingStringReader$32(FastReaderBuilder.java:440)
at
org.apache.avro.io.FastReaderBuilder.lambda$createUnionReader$30(FastReaderBuilder.java:412)
at
org.apache.avro.io.FastReaderBuilder.lambda$createFieldSetter$1(FastReaderBuilder.java:181)
at
org.apache.avro.io.FastReaderBuilder$RecordReader.read(FastReaderBuilder.java:575)
at
org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:150)}}
*Root cause:*
In {{FastReaderBuilder.getTransformingStringReader()}} (line 440), the code
casts the result of {{stringReader.read()}} directly to {{{}String{}}}:
{{return (old, decoder) -> transformer.apply((String) stringReader.read(null,
decoder));}}
However, when using {{{}GenericData{}}}, the string reader returns
{{{}Utf8{}}}, not {{{}String{}}}. This causes the {{{}ClassCastException{}}}.
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