Fix PostGIS dataprovider to check for unique data with SQL where clause

[jpalmer]

The method QgsPostgresProvider::uniqueData within qgspostgresprovider.cpp should be updated to use the SQL where cause for determining if the set primary key provides unique data.

i.e

  if ( !sqlWhereClause.isEmpty() )
  {
    sql += " where " + sqlWhereClause;
  }

[jef]

the where clause can be changed later, to the id needs to be unique even without the where clause. An alternative would be to create a view with the desired clause.

[jef]

s/to/so/

[jpalmer]

The case I was wanting to implement already involves a view. It would be useful to use the where cause to show different spatial datasets based on this view.

How about modifying the QgsPostgresProvider::setSubsetString method to recheck for the unique primary key by calling the QgsPostgresProvider::uniqueData() method?

I would be really great to have this feature so I can build a python plug-in to dynamically add and view multiple vector layers based on a dataset identifier.

[jef]

Replying to jpalmer:

How about modifying the QgsPostgresProvider::setSubsetString method to recheck for the unique primary key by calling the QgsPostgresProvider::uniqueData() method?

good point. Thanks.

Fixed in r11703