[PATCH] OGRLayer::GetFeature() does not clear filters

[warmerdam]

Calling GetFeature(id) after setting filters will not get that feature if it is excluded by the filters. I am not convinced this is the correct behavior.

NOTE: this is in the situation of using the default OGRLayer::GetFeature() implementation.

[Even Rouault]

I also agree, and this behaviour goes against the documentation of the function : "Success or failure of this operation is unaffected by the spatial or attribute filters."

Ideally we should clear the filters when entering OGRLayer::GetFeature() and restoring them when exiting, but for implementations that have overridden SetAttributeFilter() and/or SetSpatialFilter() and don't call the base methods, I don't know how we can do the restauration.

[Even Rouault]

Attached a proposed fixed for that issue :

• it adds a m_pszAttrQueryString attribute in OGRLayer that is set by OGRLayer::SetAttributeFilter(), and must be set by specialized implementations that don't fallback on OGRLayer::SetAttributeFilter()
• OGRLayer::GetFeature(): unset attribute&spatial filters, and restore them back
• test_ogrsf: add testing that attribute&spatial filters are ignored by GetFeature(), and well restored afterwards
• fix OGDI GetFeature() so that it doesn't evaluate attribute&spatial filters
• make PG, MySQL, MSSQLSpatial, OCI, SDE, PGeo, ODBC, WALK, IDB, SQLite and INGRES driver set the m_pszAttrQueryString attribute in their SetAttributeFilter() implementation. For those drivers, the generic GetFeature() is called on tables without feature id column that use, so if not setting m_pszAttrQueryString, the generic GetFeature() wouldn't be able to restore the original attribute filter

[warmerdam]

Wow, sounds good. Don't hesitate to apply it.

I think it's worth sending an email clarifying the behavior expectations to the mailing list and perhaps make it clear in the GetFeature() docs that it is not / should not be affected by filters in place.

Thanks!

[Even Rouault]

trunk r26688 "GetFeature(): make sure that the behaviour is not influenced by attribute or spatial filters in the generic implementation (by adding a m_pszAttrQueryString layer member to properly save/restore attribute filter); upgrade OGDI, PG, MySQL, MSSQLSpatial, OCI, SDE, PGeo, ODBC, WALK, IDB, SQLite and Ingres driver to be compliant with expected behaviour; make test_ogrsf test the intended behaviour (#5309)"