These may represent additional layers such as layers which
are not included in the map layer registry, or paths to
layers which have not yet been loaded into QGIS.
literal defaults, and qgis expression defaults) and automatically
handle unique value constraints on layers
Add a new method QgsVectorLayerUtils::createFeature which returns
a new feature which includes all relevant defaults. Any fields
with unique value constraints will be guaranteed to have a value
which is unique for the field.
Currently only in use by the split feature tool.
Sponsored by Canton of Zug and the QGEP project
Returns a new unique attribute value for a layer. For numeric
fields this is the max attribute value + 1, for strings we
attempt to create a unique value by append _1, _2, etc to either
a specified 'seed' value, or failing that to the end of the
value of that field from the first feature in the layer.
a substring from a vector data provider
Base implementation iterates through all features, but
providers can override with optimised versions. Native
implementations for postgres, spatialite and OGR included.
Within the attribute table, there is a new button to trigger actions
which are not based on individual features but instead on the whole layer.
Normally they will perform actions based on all features or the selection.
In addition to this, a lot of cleanup has been done.
- A new favorite grouping system was added, which the symbols list
widget defaults to
- The selected tag / smartgroup in the symbols list widget now
persists when switching layers (and across sessions)
- The symbols list widget will update the tag / smartgroup combo
box when users add / rename / remove categories
- Users can now directly tag, as well as add to favorites, symbols
while saving those to the style database
- To streamline style management, groups have been removed and
fully replaced by tags
- Tags have been integrated into the import/export user interface
Implements a method in QgsGeometry and a processing algorithm to
calculate the pole of inaccessibility for a surface, which is the
most distant internal point from the boundary of the surface. This function
uses the 'polylabel' algorithm (Vladimir Agafonkin, 2016), which is an iterative
approach guaranteed to find the true pole of inaccessibility within a specified
tolerance. More precise tolerances require more iterations and will take longer
to calculate.
default value SQL clauses
QgsVectorDataProvider now has two methods:
- defaultValueClause: returns SQL fragment which must be evaluated
by the provider to obtain the default value, eg sequence values
- defaultValue: returns the literal constant default value
for a field
Warnings are shown, but features can be committed. Fields which
fail an unenforced constraint are now shaded in yellow to differentiate
from the red failure for enforced constraints.
Non-enforced constraints just show a warning to the user, but
do not prevent committing the feature. Enforced constraints
block users from comitting non compliant features.
Any constraints detected by the provider are always
enforced.
and not any constraints enforced by the provider
Because:
1. we want to keep browsing features nice and responsive. It's nice to give
feedback as to whether the value checks out, but not if it's too slow to
do so. Some constraints (eg unique) can be expensive to test. A user can
freely remove a layer-based constraint if it proves to be too slow to
test, but they are unlikely to have any control over provider-side
constraints
2. the provider has already accepted the value, so presumably it doesn't
violate the constraint and there's no point rechecking!
