# ES 7.8.0 plugin development - onIndexModule questions

**URL:** <https://discuss.elastic.co/t/es-7-8-0-plugin-development-onindexmodule-questions/263848>\
**Category:** Elasticsearch\
**Created:** [February 10, 2021, 10:16am UTC](https://discuss.elastic.co/t/es-7-8-0-plugin-development-onindexmodule-questions/263848 "2021-02-10T10:16:15Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Tom\_Elias](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/tom_elias/32/72245_2.png) [@Tom\_Elias](https://discuss.elastic.co/u/Tom_Elias)\
**Post date:** [February 10, 2021, 10:16am UTC](https://discuss.elastic.co/t/es-7-8-0-plugin-development-onindexmodule-questions/263848/1 "2021-02-10T10:16:15Z")

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Hello,  
I am currently developing a plugin for Elasticsearch and trying out the new dense\_vector data type.  
what i'm currently trying to do is register a PostIndexOperationListener and IndexOperationEventListener objects for any index which has a dense\_vector field in my cluster. i do this by overriding onIndexModule in my plugin, but unfortunately i can't get the index mapping except by reflection of the private members of IndexModule (IndexModule -\> IndexSettings -\> IndexMetadata -\> ImmutableOpenMap...).  
is there another way i can explore the index mapping from within onIndexModule method?

another issue is when adding a new dense\_vector field to an existing index, i would like to be able to react to the mappings change and install my listeners. however, in the onIndexModule method, again using reflection, i get the version of the mappings before the change is applied (meaning the new field is not in the mappings).  
is there a way i can react to the mappings change and get the most updated version of the mappings?

Thanks,  
-- Tom Elias.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [March 10, 2021, 10:16am UTC](https://discuss.elastic.co/t/es-7-8-0-plugin-development-onindexmodule-questions/263848/2 "2021-03-10T10:16:27Z")

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