Hi everybody

I have the following problem. I'm doing a FullTextQuery and would like to use Projection instead of retrieving the objects from the Database.

I stored a key Value in the lucene index. - which is retrieved by my projection. - But i also need to know the "_hibernate_class" field value, but the projection does not return it (checking with luke it clearly is stored in the index)

I tried:

fullTextQuery.setProjection("keyobject",DocumentBuilder.CLASS_FIELDNAME)

and also

fullTextQuery.setProjection("keyobject", "_hibernate_class")

both leave me hanging with no value returned for [1] and the correct keyobject for [0].

Is hibernate-search hiding this field from me? - and if so, is there a way to retrieve it anyway?

Thanks for reading,

greetings
JP

Update - I found a (simple) way to access the filed anyway:

fullTextQuery.setProjection("keyobject", FullTextQuery.DOCUMENT)

And in the resulting projection array i can access the filed of the lucene document and get my classname:

Document doc = (Document)objects[1];
String classname = doc.getField("_hibernate_class").stringValue();


But I am not sure how much overhead this is creating - and i am still unsure why _hibernate_class can't be projected "normally".

So any information is still appreciated.

Thanks again for reading.

Hi,

the reason you cannot project on _hibernate_class is that is neither a configured indexed property nor a valid ProjectionConstant. You are basically projecting on a field which is (currently) not part of the public API. The classname is currently indexed due to the fact that it is possible to have instances of more than one entity in the same index. In this case it is of course not enough any more to just rely on the entity id.

One could argue why CLASS_FIELDNAME is not treated as ProjectionConstant as well. I don't have a clear answer for that right now.

--Hardy

thanks for the answer. - i'll use the lucene document projection for now.

If the class ever gets add to the projection constants i'll change my implementation to use that.

The lucene document is loaded anyway when searching, so i guess and hope accessing it via projection will not create that much overhead - and i think it is better to access the lucenedoc then to store the objects class in another field (by using a classbridge) and accessing that field via projection.

+1 to expose managed object class via a Projection constant

You should create a Jira issue for it then.

Done.

http://opensource.atlassian.com/project ... SEARCH-296