Xapian discuss - Dec 2009 - Combined search in multiple fields help

Hello,

I want to let user specify by drop down list to what fields his query will be
searched. For example "Full-text" or "Title+Author", then
user enters search query as usual (without using prefixes). But how to modify
query so it cover two fields in a right way?

For a starter how I think about modifying query to limit it just to single
globally selected field:
1. after user enters free-text query I parse it as usual via parse_query(),
2. then I iterate through resulting Xapian::Query by get_terms and apend A or S
prefix to evey term (after Z if Z is present, and not appending where other
prefix is already applied (for example H)).
(Btw, is this optimal strategy?)

What I think about multiple fields and where it fail:
There is two situation depending on default_op().
'or') I just duplicate parsed query as whole and add different prefix to
each of them, then combine these big queries with 'or'.
'and') hard part begin, probably I should duplicate each term, add one
prefix to original and other to clone and combine it with OR with existing term.
Right? Will this be possible? Any suggestions?

Don.

Hi Don,

Probably the simplest way to do this (if I understand your
requirements correctly) is to use QueryParser::add_prefix()
(http://shrunk.net/63b17360 ).  If you provide an empty field name,
any prefixes you set will be added to 'bare' terms. So if you want to
search prefixes XA and XB by default:

qp = QueryParser();
...
qp.add_prefix("", "XA");
qp.add_prefix("", "XB");
...

If you make this dependent on the dropdown value the user has
selected, I think it will do what you want.

Tom


2009/12/13 Do. <do1 at yandex.ru>:
> Hello,
>
> I want to let user specify by drop down list to what fields his query will
be searched. For example "Full-text" or "Title+Author", then
user enters search query as usual (without using prefixes). But how to modify
query so it cover two fields in a right way?
>
> For a starter how I think about modifying query to limit it just to single
globally selected field:
> 1. after user enters free-text query I parse it as usual via parse_query(),
> 2. then I iterate through resulting Xapian::Query by get_terms and apend A
or S prefix to evey term (after Z if Z is present, and not appending where other
prefix is already applied (for example H)).
> (Btw, is this optimal strategy?)
>
> What I think about multiple fields and where it fail:
> There is two situation depending on default_op().
> 'or') I just duplicate parsed query as whole and add different
prefix to each of them, then combine these big queries with 'or'.
> 'and') hard part begin, probably I should duplicate each term, add
one prefix to original and other to clone and combine it with OR with existing
term. Right? Will this be possible? Any suggestions?
>
> Don.
>
>
>
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