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https://issues.apache.org/jira/browse/AVRO-530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17731530#comment-17731530
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Christophe Le Saec commented on AVRO-530:
-----------------------------------------
*Back to this JIRA :*
[~kniemitalo] :
- the proposed [PR|https://github.com/apache/avro/pull/1768] works also with
"forward references" (tested with your example)
- it preserves Canonical Form result, with example, it generates :
{code:json}
{"name":"Main","type":"record",fields":[{"name":"f1","type":{"name":"Sub","type":"enum","symbols":["OPEN","CLOSE"]}},{"name":"f2","type":"Sub"}]}
{code}
But, in java, it also allow recursing type, as
{code:json}
{ "protocol" : "recurse", "types": [
{"name": "Parent", "type": "record", "fields": [{"name": "childs", "type":{
"type":"array", "items": "Child"}}]},
{"name": "Child", "type": "record", "fields": [{"name": "parent", "type":
"Parent"}]}
]}
{code}
that works fine until we try to serialize it with encoder ... throwing
StackOverflowError exception ...
({_}in rust, borrowing mechanism seems to prevent that kind of issue{_})
> allow for mutual recursion in type definitions
> ----------------------------------------------
>
> Key: AVRO-530
> URL: https://issues.apache.org/jira/browse/AVRO-530
> Project: Apache Avro
> Issue Type: Improvement
> Components: spec
> Affects Versions: 1.3.2
> Reporter: Jeff Hodges
> Assignee: Christophe Le Saec
> Priority: Major
> Labels: pull-request-available
>
> Suppose you have these two types in your protocol:
> {code}
> {"name": "User", "type": "record", "fields": [{"name": "current_status",
> "type": "Status"}]}
> {"name": "Status", "type": "record", "fields": [{"name": "author", "type":
> "User"}]}
> {code}
> This will raise an error! The current workaround is to define one of them at
> their first usage. Like:
> {code}
> {"name": "User", "type": "record", "fields": [{"name": "current_status",
> "type": {"name": "Status", "type": "record", "fields": [.. lots of fields
> ...]}]}
> {code}
> But this is incredibly unwieldy. It would be really nice for the spec to
> require all the parsers to allow for mutual recursion, instead. It could be
> done by implementing a two-pass parser. One pass to acquire names referenced,
> and a second to fill in those names with their appropriate references.
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