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https://issues.apache.org/jira/browse/THRIFT-5544?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Liu Jiayu reassigned THRIFT-5544:
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Assignee: Liu Jiayu
> add java code gen param to support including field annotation as metadata
> -------------------------------------------------------------------------
>
> Key: THRIFT-5544
> URL: https://issues.apache.org/jira/browse/THRIFT-5544
> Project: Thrift
> Issue Type: Improvement
> Components: Java - Compiler, Java - Library
> Reporter: Liu Jiayu
> Assignee: Liu Jiayu
> Priority: Minor
> Time Spent: 50m
> Remaining Estimate: 0h
>
> Currently the code generator has a map of string to string field that denotes
> the "annotations" for a field:
> [https://github.com/apache/thrift/blob/90ea2e8398eda32da8be0b3514516e7ad932a869/compiler/cpp/src/thrift/parse/t_field.h#L109]
> It is made available to generators such as JSON (in
> [https://github.com/apache/thrift/blob/90ea2e8398eda32da8be0b3514516e7ad932a869/compiler/cpp/src/thrift/generate/t_json_generator.cc#L267-L274])
> to allow (runtime) interpretation of such metadata.
> In Java, similar mechanism exists to register field metadata (via
> [https://github.com/apache/thrift/blob/90ea2e8398eda32da8be0b3514516e7ad932a869/compiler/cpp/src/thrift/generate/t_java_generator.cc#L2862-L2865]
> which calls `org.apache.thrift.meta_data.FieldMetaData#addStructMetaDataMap`
> method to register into a centralized places. Such metadata is useful, e.g.
> the microservice framework Ameria uses it
> ([https://github.com/line/armeria/blob/5c2efebc7ba2350540d0554f530c173a49eb4c19/thrift0.13/src/main/java/com/linecorp/armeria/server/thrift/THttpService.java#L553-L554])
> to dynamically proxy requests.
> However the existing field metadata only contain information about field id,
> type, and name, but it does not contain annotations. Adding annotations will
> be useful for situations e.g. (these are useful enablement at user side, make
> possible if annotation is included)
> * some static metadata is useful at runtime for dynamic operations, e.g.
> like what `deprecated` means in the context of a field, adding `obfuscated`
> allows the user site to decide to obfuscate detailed information
> * allows for more richer and more type specific validation and
> transformation logic, e.g. since we can only have string as field type,
> adding `date_format="YYYY-MM-DD"` allows the thrift struct to be interpreted
> as a local date and thus can automatically be converted to java.time.LocalDate
> This should be a back-compatible change as the default behavior is _not_ to
> include the annotation. A second constructor can be added to allow included
> annotation to exist and register.
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