Solr conditional query fields (qf) - search

Question

Is it possible to define query fields in Solr based on certain conditions? For e.g. I've three fields text, title and product.The solr config definition:
<str name="qf">text^0.5 title^10.0 Product</str>
What I'm looking here is to include "product" as a searchable field only when certain condition is met, for e.g. if author:"Tom", then search in Product as well.
Is there a way to do that during query time using edismax ?
The alternate I've is to add the product information to either text or title of the document (where author=Tom) during index time so it'll be searchable. But, I'm trying to avoid this if possible.
Any pointers will be appreciated.
-Thanks

Answer 1

In order to search in different fields based on different conditions, there is a need to first search for that specific conditions, thus it is more or less the same as issuing multiple queries.
That said, in case there is a need to do it as a one-time query (e.g. for out-of-the-box sorting/grouping/other solr features), the nested queries can be used.
For defining two different conditions (as in the original question, but it can easily be extended with more OR clauses), the q parameter can receive following value:
_query_:"{!edismax fq=$fq1 qf=$qf1 v=$condQuery}"
OR
_query_:"{!edismax fq=$fq2 qf=$qf2 v=$condQuery}"
The query uses Parameter Dereferencing, so there is no need to manually escape any special characters before passing the parameters to solr.
fq1 - first special condition
qf1 - list of fields to search in for first special condition (fq1)
fq2 - second special condition
qf2 - list of fields to search in for first special condition (fq2)
condQuery - the actual search term/query
The fq1 may be empty in order to define a baseline (in this particular case - search in text and title, but not in product).
The raw parameters themselves will look the following way:
fq1=&qf1=text^0.5 title^10.0&fq2=author:"Tom"&qf2=text^0.5 title^10.0 Product&condQuery=5
And the Final query will be something like this:
http://localhost:8983/solr/collection1/select?q=_query_%3A%22%7B!edismax+fq%3D%24fq1+qf%3D%24qf1+v%3D%24condQuery%7D%22+OR+_query_%3A%22%7B!edismax+fq%3D%24fq2+qf%3D%24qf2+v%3D%24condQuery%7D%22&fl=*%2Cscore&wt=xml&indent=true&fq1=&qf1=text^0.5%20title^10.0&fq2=author:%22Tom%22&qf2=text^0.5%20title^10.0%20Product&condQuery=5
.. or the same query returned by solr in solr response (provided only for showing it in a structured way):
<response>
<lst name="responseHeader">
<int name="status">0</int>
<int name="QTime">1</int>
<lst name="params">
<str name="q">_query_:"{!edismax fq=$fq1 qf=$qf1 v=$condQuery}" OR _query_:"{!edismax fq=$fq2 qf=$qf2 v=$condQuery}"</str>
<str name="condQuery">5</str>
<str name="indent">true</str>
<str name="fl">*,score</str>
<str name="fq1"/>
<str name="qf1">text^0.5 title^10.0</str>
<str name="fq2">author:"Tom"</str>
<str name="qf2">text^0.5 title^10.0 Product</str>
<str name="wt">xml</str>
</lst>
</lst>
<result name="response" numFound="..." start="..." maxScore="...">
...
</result>
</response>
Even though it works, I suggest to consider the effect it would have on query time (as each condition will have a separate internal search query) and measure how it affects your specific case.

Answer 2

I didn't try it by myself, but it looks like this could be achievable by using http://wiki.apache.org/solr/FunctionQuery#Boolean_Functions

Answer 3

Shamik,
I don't think there is a way to do this in Solr that is easy. One thing to consider is managing of these rules overtime too, it would be a nightmare for a large system.
If you really wanted to do something like this, maybe you can issue two calls to Solr to get the result set.