Reindexing objects is not automatically running on ruby on rails

[mzane42]

Hi,
i'm using Sunspot Solr for indexing and searching in our Ruby on Rails application with MangoDB
database (Mongo mapper)

The searching works well, but objects aren't automatically indexed to Solr when i make changes on my database.

I tried manually index on a class itself:

Top.reindex
Sunspot.commit

Or, I added on sunspot.yml :

auto_commit_after_request: true

I also autocommit with some interval on solrconfig.xml :

<autoCommit>
<maxDocs>10000</maxDocs>
<maxTime>15000</maxTime>
</autoCommit>

All this solutions failed to reindex automatically my objects, unless i reindex all objects with rake task :

bundle exec rake sunspot:reindex

Any other solutions ?

Thanks a lot.