Thorsten Hake created AVRO-2702:
-----------------------------------
Summary: Avro ResolvingGrammarGenerator does not honor
"avro.java.string" property in inner record schemas
Key: AVRO-2702
URL: https://issues.apache.org/jira/browse/AVRO-2702
Project: Apache Avro
Issue Type: Bug
Components: java
Affects Versions: 1.9.1
Reporter: Thorsten Hake
Attachments: Bar.kt
The type property "avro.java.string" is being used to qualify the CharSequence
implementation of a string type in java. This property will be set in the java
code generated by the avro maven plugin, if the <stringType> property is set to
"String".
However the ResolvingGrammarGenerator, which helps in matching the writer
schema to the reader schema, does not honor this property for inner records
within unions. Instead of deserializing to java.lang.String, the strings of the
inner record will be deserialized to org.apache.avro.util.Utf8. String
properties belonging to the outer record will be correctly deserialized to
java.lang.String.
If you try to deserialize an Avro record from a schema that has an inner record
within an union type with the java code generated by the maven plugin
(<stringType> is set to "String"), you'll get a ClassCastException:
{noformat}
Caused by: java.lang.ClassCastException: class org.apache.avro.util.Utf8 cannot
be cast to class java.lang.String
{noformat}
This is because the generated java code expects the strings to be deserialized
according to the "avro.java.string" property which does not happen for the
inner record.
I would expect that the deserializer treats the strings in the inner record the
same as the strings in the outer record.
Example:
writer schema:
{code:json}
{
"type": "record",
"name": "foo",
"fields": [
{
"name": "k",
"type": "string"
},
{
"name": "value",
"type": [
"null",
{
"type": "record",
"name": "bar",
"fields": [
{
"name": "str",
"type": "string"
}
]
}
]
}
]
}
{code}
reader schema:
{code:json}
{
"type": "record",
"name": "foo",
"fields": [
{
"name": "k",
"type": {
"type": "string",
"avro.java.string": "String"
}
},
{
"name": "value",
"type": [
"null",
{
"type": "record",
"name": "bar",
"fields": [
{
"name": "str",
"type": {
"type": "string",
"avro.java.string": "String"
}
}
]
}
]
}
]
}
{code}
You'll find some example kotlin code demonstrating the problem in the attached
Bar.kt.
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