Xapian discuss - Mar 2007 - Phrase query problem with python api

Hi all,

I'm pretty new to xapian and I can't seem to see what's wrong with
this code.

      1 '''
      2 This module provides some examples of how to use the xapian API
      3 '''
      4
      5 import xapian
      6 def test_near():
      7     xapian.Query(xapian.Query.OP_PHRASE, 'abc', 'def')
      8     q_phrase = xapian.Query(xapian.Query.OP_PHRASE, ("smoke",
"test", "tuple"))
      9     q_xor = xapian.Query(xapian.Query.OP_XOR,
(xapian.Query('smoke'), q_phrase, 'string'))
     10     q_phrase_comp = xapian.Query(xapian.Query.OP_PHRASE,
(q_phrase, q_xor))

The query in line 10 bombs out with:

Traceback (most recent call last):
  File
"/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/nose-0.9.2-py2.4.egg/nose/case.py",
line 52, in runTest
    self.testFunc()
  File "/Users/victorng/dev/bzr_repo/test_xapian.py", line 10, in
test_near
    q_phrase_comp = xapian.Query(xapian.Query.OP_PHRASE, (q_phrase, q_xor))
  File
"/Library/Frameworks/Python.framework/Versions/2.4/lib/python2.4/site-packages/xapian.py",
line 473, in __init__
    _xapian.Query_swiginit(self,_xapian.new_Query(*args))
RuntimeError: unknown error in Xapian


Aren't PHRASE queries allowed to take arbitrary subqueries or does it
only allow some kinds of subqueries?

vic

Victor Ng wrote:
> line 473, in __init__
>    _xapian.Query_swiginit(self,_xapian.new_Query(*args))
> RuntimeError: unknown error in Xapian
> 
> 
> Aren't PHRASE queries allowed to take arbitrary subqueries or does it
> only allow some kinds of subqueries?
PHRASE queries aren't allowed to contain subqueries which are PHRASE or 
NEAR subqueries.  In SVN Xapian, the exception message from your code is 
more helpful:

xapian.UnimplementedError: Can't use NEAR/PHRASE with a subexpression 
containing NEAR or PHRASE

Actually, if I recall correctly, NEAR and PHRASE pretty much only accept 
single-term subqueries currently, though I may be out of date on this 
point.  I've never needed to perform these kinds of queries - if you can 
find examples of real-world queries which need support for this, it 
might encourage someone to develop support for it sooner rather than later.

-- 
Richard