[Qgis-developer] QgsDataProvider and supportsSubsetString

Nathan Woodrow madmanwoo at gmail.com
Mon Apr 29 23:55:56 PDT 2013


Also not there is previsions to add this kind of thing to QgsFeatureRequest

- Nathan

On Tue, Apr 30, 2013 at 4:33 PM, Chris Crook <ccrook at linz.govt.nz> wrote:

> Hi All
> As we are looking at API tidy ups (I understand), would there be any
> support for providing a bit more granularity in supportsSubsetString.  At
> the moment this is a simple boolean, and the GUI offers a SQL based subset
> string builder.
> However not all providers naturally use SQL based strings.  I'm interested
> in adding subset capability to the delimited text provider, whichi I've
> done using QgsExpression as the basis for subsets.  This works very well
> except that the GUI isn't an expression builder.  I think there may be
> similar issues with the WFS provider.
> What I am proposing is something more like an enum
> QgsDataProvider::SubsetStringType, which could then be interrogated by the
> properties dialog to select the appropriate query builder dialog.
> Logically this would supplant the supportsSubsetString boolean which could
> be deprecated, replaced with
> virtual QgsDataProvider::SubsetStringType
> QgsDataProvider::subsetStringType(){ return NoSubsetString; }
> Other types could be SqlSubsetString, ExpressionSubsetString, ...?
> Thoughts anyone?
> Thanks
> Chris
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