[QGIS-trac] [Quantum GIS] #3337: Query Builder's data sampler doesn't use original dataset

[Quantum GIS]

#3337: Query Builder's data sampler doesn't use original dataset
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   Reporter:  arencambre        |              Owner:  jef          
       Type:  bug               |             Status:  new          
   Priority:  minor: annoyance  |          Milestone:  Version 1.7.0
  Component:  Vectors           |            Version:  1.6.0        
   Keywords:                    |   Platform_version:  7 x86        
   Platform:  Windows           |           Must_fix:  No           
Status_info:  0                 |  
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 Suppose you use the Query Builder to filter data on a layer. Now suppose
 you want to later refine the query, perhaps by adding back some data you
 previously filtered our.

 If I click on a field on the left side and then hit '''Sample''' or
 '''All''' under '''Values''', the values are only returned from the
 filtered dataset, not from the original dataset.

 Here's where it's a problem: I have a vector layer with field
 '''rte_class''' with values '''County Roads''', '''FC Streets''', '''On
 System Highways''', and '''Toll Roads'''. I previously filtered the
 dataset so the '''SQL where clause''' says '''"rte_class" = 'On System
 Highways''''. But I wanted to go back and add another value, but I don't
 remember what it is. I clicked on '''rte_class''' under '''Fields''' and
 hit '''All''' under '''Values''', and the only value presented is '''On
 System Highways'''. The only way I got the other three fields back is to
 clear the filter and start over.

 I think that sampled data should come from the original dataset, not the
 filtered version of the data. I've been debating bug vs. enhancement for
 this, but I think it's a bug because it precludes using the Query Builder
 to relax a filter unless I clear the filter totally.

 Only after clearing the filter was I able to produce the desired where
 clause: '''"rte_class" = 'On System Highways' OR "rte_class" = 'Toll
 Roads''''.

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Ticket URL: <http://trac.osgeo.org/qgis/ticket/3337>
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