Hi, Lucene Document is a set of fields. Each field has a name and a textual value. There is no notion of nested fields (filed inside a filed). Do not focus too much on the XML representation of the index obtained from Luke. Read Lucene documentation instead. When indexing a java bean then what in fact has to happen is that you have to transform tree-like data structure to a linear form: to one vector (document) of vectors (fields). And this means that you have to lose some information. In this case you are loosing mandatory - courseName relation. Thus you have to keep this relation in arbitrary field in index - as long as you want to have just ONE student Bob in your index. One option here is what I have described before - adding a new fields into Student. These fileds will somehow keep the mandatory - courseName relation.
If you can have many Bobs in the index then the Student class can not be a searchable root and you have to change you Compass mappings. Regards, Lukas http://blog.lukas-vlcek.com/ On Thu, Jul 30, 2009 at 11:36 PM, Paolo DiCanio <domur...@yahoo.co.uk>wrote: > > Thanks Steven, > > I guess the index structure that I need in order to perform my query is: > > <doc id='1'> > <field name='courseName'> > <val>cooking</val> > <field name='mandatory'> > <val>N</val> > </field> > </field> > <field name='courseName'> > <val>art</val> > <field name='mandatory'> > <val>Y</val> > </field> > <field name='name'> > <val>Bob</val> > </field> > </doc> > > But I'm not sure how to map my domain classes in order to achieve this (or > even if it's possible) > > > Steven A Rowe wrote: > > > > Hi Donal, > > > > I looked at the XML index dump you provided, and I can see that there is > > only one document in the index. This document matches your query. I've > > pasted it below, without the "$/*"-named fields I'm assuming Compass adds > > to manage Lucene document -> Grails object mapping, and with just the > > "name" attribute on the field elements: > > > > <doc id='1'> > > <field name='courseName'> > > <val>cooking</val> > > <val>art</val> > > </field> > > <field name='mandatory'> > > <val>N</val> > > <val>Y</val> > > </field> > > <field name='name'> > > <val>Bob</val> > > </field> > > </doc> > > > > Compass's Lucene document to Grails object mapping is your problem here. > > > > In Lucene-land, the query (+courseName:cooking +mandatory:Y) matches the > > above document, because the document contains those values in those > > fields. > > > > So with that query, based on the Lucene document structure, you seem to > be > > asking the question: "Which student attends a cooking course and also > > attends a mandatory course?". Bob is a match. > > > > Steve > > > >> -----Original Message----- > >> From: Donal Murtagh [mailto:domur...@yahoo.co.uk] > >> Sent: Thursday, July 30, 2009 3:10 PM > >> To: java-user@lucene.apache.org > >> Subject: Re: Querying across object relationships > >> > >> Basically the classes I'm indexing have the following relationships: > >> > >> Student 1------* Attendance 1------* Course > >> > >> The > >> only root class is Student, i.e. only instances of this class can be > >> returned from a search. I have a Student object graph that could be > >> represented in JSON as follows: > >> > >> { > >> name: Bob, > >> attendances: [ > >> {mandatory: N, course: {name: cooking}}, > >> {mandatory: Y, course: {name: art}}] > >> } > >> > >> When I search for an instance of Student using the query: > >> > >> "+courseName:cooking +mandatory:Y" > >> > >> Bob > >> is returned because, because he attends a course named "cooking" and he > >> attends a mandatory course (named "art).. But what I really want to > >> search for is students that attend a mandatory cooking course. It > >> doesn't appear to be possible to do this based on the responses > >> provided here: > >> http://stackoverflow.com/questions/1202422/lucene-query- > >> syntax/1203186#1203186 > >> > >> I > >> opened the Student index in Luke, exported it to XML and have appended > >> the results here: > >> http://pastebin.com/m6e5bbcf3 > >> > >> I don't really know how to interpret this > >> myself, but thanks in advance for any further help you can provide. > >> > >> - Don > >> > >> > >> > >> > > > > > > -- > View this message in context: > http://www.nabble.com/Querying-across-object-relationships-tp24727196p24747745.html > Sent from the Lucene - Java Users mailing list archive at Nabble.com. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > >
