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[FEATURE] Add `with edit(layer):` to python

Example:

    with edit(layer):
        f=layer.getFeatures().next()
        f[0]=5
        layer.updateFeature(f)

This will automatically call commitChanges() in the end.
If any exception occurs, it will rollBack() all the changes.
  • Loading branch information
m-kuhn committed Aug 12, 2015
1 parent 45d4dbe commit 35fc2902f332435f3f8ccbce53cfc6c9fe8611a8
Showing with 98 additions and 0 deletions.
  1. +21 −0 python/__init__.py
  2. +1 −0 tests/src/python/CMakeLists.txt
  3. +76 −0 tests/src/python/test_syntactic_sugar.py
@@ -72,6 +72,27 @@ def __hash__(self):
except ImportError:
pass

# Define a `with edit(layer)` statement

class edit:
def __init__(self,layer):
self.layer = layer

def __enter__(self):
assert self.layer.startEditing()
return self.layer

def __exit__(self, ex_type, ex_value, traceback):
if ex_type is None:
assert self.layer.commitChanges()
return True
else:
self.layer.rollBack()
return False

from qgis import core
core.edit = edit


def mapping_feature(feature):
geom = feature.geometry()
@@ -52,6 +52,7 @@ ADD_PYTHON_TEST(PyQgsSpatialiteProvider test_provider_spatialite.py)
ADD_PYTHON_TEST(PyQgsShapefileProvider test_provider_shapefile.py)
ADD_PYTHON_TEST(PyQgsMemoryProvider test_provider_memory.py)
ADD_PYTHON_TEST(PyQgsVectorColorRamp test_qgsvectorcolorramp.py)
ADD_PYTHON_TEST(PyQgsSyntacticSugar test_syntactic_sugar.py)

IF (NOT WIN32)
ADD_PYTHON_TEST(PyQgsLogger test_qgslogger.py)
@@ -0,0 +1,76 @@
# -*- coding: utf-8 -*-
"""QGIS Unit tests for some syntactic sugar in python
.. note:: This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
"""
__author__ = 'Matthias Kuhn'
__date__ = '12.8.2015'
__copyright__ = 'Copyright 2015, The QGIS Project'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'

import qgis

from utilities import (unittest,
TestCase,
getQgisTestApp
)
from qgis.core import (edit,
QgsFeature,
QgsGeometry,
QgsVectorLayer
)

getQgisTestApp()

class TestSyntacticSugar(TestCase):

def testEdit(self):
"""Test `with edit(layer):` code"""

ml=QgsVectorLayer("Point?crs=epsg:4236&field=id:integer&field=value:double",
"test_data", "memory")
# Data as list of x, y, id, value
assert ml.isValid()
fields=ml.fields()

# Check insert
with edit(ml):
feat=QgsFeature(fields)
feat['id']=1
feat['value']=0.9
assert ml.addFeature(feat)

assert ml.dataProvider().getFeatures().next()['value']==0.9

# Check update
with edit(ml):
f = ml.getFeatures().next()
f['value']=9.9
assert ml.updateFeature(f)

assert ml.dataProvider().getFeatures().next()['value']==9.9

# Check for rollBack after exceptions
with self.assertRaises(NameError):
with edit(ml):
f = ml.getFeatures().next()
f['value']=3.8
crashycrash()

assert ml.dataProvider().getFeatures().next()['value']==9.9
assert ml.getFeatures().next()['value']==9.9

# Check for `as`
with edit(ml) as l:
f = l.getFeatures().next()
f['value']=10
assert l.updateFeature(f)

assert ml.dataProvider().getFeatures().next()['value']==10

if __name__ == "__main__":
unittest.main()

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