[
https://issues.apache.org/jira/browse/ARROW-11114?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17257936#comment-17257936
]
Nick B commented on ARROW-11114:
--------------------------------
[~fan_li_ya] Sure, I took a first pass at a solution in this PR:
https://github.com/apache/arrow/pull/9088
> [Java] Metadata serialization is broken for Field class
> -------------------------------------------------------
>
> Key: ARROW-11114
> URL: https://issues.apache.org/jira/browse/ARROW-11114
> Project: Apache Arrow
> Issue Type: Bug
> Components: Java
> Affects Versions: 2.0.0
> Reporter: Nick B
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> org.apache.arrow.vector.types.pojo.Field uses asymmetric serialization and
> deserialization for the metadata field, causing it to fail to deserialize
> with the following error:
> {noformat}
> Exception in thread "main"
> com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot
> deserialize instance of `java.util.ArrayList` out of START_OBJECT
> tokenException in thread "main"
> com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot
> deserialize instance of `java.util.ArrayList` out of START_OBJECT token at
> [Source: (File); line: 10, column: 20] (through reference chain:
> org.apache.arrow.vector.types.pojo.Schema["fields"]->java.util.ArrayList[0]->org.apache.arrow.vector.types.pojo.Field["metadata"])
> {noformat}
> This is because the class [serializes
> metadata|https://github.com/apache/arrow/blob/dfef236f7587e4168ac1e07bd09e42d9373beb70/java/vector/src/main/java/org/apache/arrow/vector/types/pojo/Field.java#L274]
> as {{Map<String, String>}} but [expects to deserialize
> it|https://github.com/apache/arrow/blob/dfef236f7587e4168ac1e07bd09e42d9373beb70/java/vector/src/main/java/org/apache/arrow/vector/types/pojo/Field.java#L87]
> as {{List<Map<String, String>>}}.
> MCVE: [https://gist.github.com/nbruno/983cb7faf41dc20a0810ae80fe33562d]
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
