Python QgsVectorLayer.updateFeature方法代码示例

# 需要导入模块: from qgis.core import QgsVectorLayer [as 别名]
# 或者: from qgis.core.QgsVectorLayer import updateFeature [as 别名]
    def add_flooded_field(self, shapefile_path):
        """Create the layer from the local shp adding the flooded field.

        .. versionadded:: 3.3

        Use this method to add a calculated field to a shapefile. The shapefile
        should have a field called 'count' containing the number of flood
        reports for the field. The field values will be set to 0 if the count
        field is < 1, otherwise it will be set to 1.

        :param shapefile_path: Path to the shapefile that will have the flooded
            field added.
        :type shapefile_path: basestring

        :return: A vector layer with the flooded field added.
        :rtype: QgsVectorLayer
        """
        layer = QgsVectorLayer(
            shapefile_path, self.tr('Jakarta Floods'), 'ogr')
        # Add a calculated field indicating if a poly is flooded or not
        # from PyQt4.QtCore import QVariant
        layer.startEditing()
        field = QgsField('flooded', QVariant.Int)
        layer.dataProvider().addAttributes([field])
        layer.commitChanges()
        layer.startEditing()
        idx = layer.fieldNameIndex('flooded')
        expression = QgsExpression('state > 0')
        expression.prepare(layer.pendingFields())
        for feature in layer.getFeatures():
            feature[idx] = expression.evaluate(feature)
            layer.updateFeature(feature)
        layer.commitChanges()
        return layer

# 需要导入模块: from qgis.core import QgsVectorLayer [as 别名]
# 或者: from qgis.core.QgsVectorLayer import updateFeature [as 别名]
    def add_flooded_field(self, shapefile_path):
        """Create the layer from the local shp adding the flooded field.

        .. versionadded:: 3.3

        Use this method to add a calculated field to a shapefile. The shapefile
        should have a field called 'count' containing the number of flood
        reports for the field. The field values will be set to 0 if the count
        field is < 1, otherwise it will be set to 1.

        :param shapefile_path: Path to the shapefile that will have the flooded
            field added.
        :type shapefile_path: basestring

        :return: A vector layer with the flooded field added.
        :rtype: QgsVectorLayer
        """
        layer = QgsVectorLayer(
            shapefile_path, self.tr('Jakarta Floods'), 'ogr')
        # Add a calculated field indicating if a poly is flooded or not
        # from qgis.PyQt.QtCore import QVariant
        layer.startEditing()
        # Add field with integer from 0 to 4 which represents the flood
        # class. Its the same as 'state' field except that is being treated
        # as a string.
        # This is used for cartography
        flood_class_field = QgsField('floodclass', QVariant.Int)
        layer.addAttribute(flood_class_field)
        layer.commitChanges()
        layer.startEditing()
        flood_class_idx = layer.fields().lookupField('floodclass')
        flood_class_expression = QgsExpression('to_int(state)')
        context = QgsExpressionContext()
        context.setFields(layer.fields())
        flood_class_expression.prepare(context)

        # Add field with boolean flag to say if the area is flooded
        # This is used by the impact function
        flooded_field = QgsField('flooded', QVariant.Int)
        layer.dataProvider().addAttributes([flooded_field])
        layer.commitChanges()
        layer.startEditing()
        flooded_idx = layer.fields().lookupField('flooded')
        flood_flag_expression = QgsExpression('state > 0')
        flood_flag_expression.prepare(context)
        for feature in layer.getFeatures():
            context.setFeature(feature)
            feature[flood_class_idx] = flood_class_expression.evaluate(context)
            feature[flooded_idx] = flood_flag_expression.evaluate(context)
            layer.updateFeature(feature)
        layer.commitChanges()
        return layer

# 需要导入模块: from qgis.core import QgsVectorLayer [as 别名]
# 或者: from qgis.core.QgsVectorLayer import updateFeature [as 别名]
def checkCartoDBId(layer, convert=False):
    """Check if layer has cartodb_id field"""
    new_layer = layer

    if convert and layer.fieldNameIndex('cartodb_id') == -1:
        checkTempDir()
        temp = tempfile.NamedTemporaryFile()
        error = QgsVectorFileWriter.writeAsVectorFormat(layer, temp.name, 'utf-8', None, 'ESRI Shapefile')
        if error == QgsVectorFileWriter.NoError:
            new_layer = QgsVectorLayer(temp.name + '.shp', layer.name(), 'ogr')
            new_layer.dataProvider().addAttributes([QgsField('cartodb_id', QVariant.Int)])
            new_layer.updateFields()
            features = new_layer.getFeatures()
            i = 1
            for feature in features:
                fid = feature.id()
                aid = new_layer.fieldNameIndex('cartodb_id')
                attrs = {aid: i}
                new_layer.dataProvider().changeAttributeValues({fid : attrs})
                i = i + 1
                new_layer.updateFeature(feature)
    return new_layer

# 需要导入模块: from qgis.core import QgsVectorLayer [as 别名]
# 或者: from qgis.core.QgsVectorLayer import updateFeature [as 别名]
    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
        self.assertTrue(ml.isValid())
        fields = ml.fields()

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

        self.assertEqual(next(ml.dataProvider().getFeatures())['value'], 0.9)

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

        self.assertEqual(next(ml.dataProvider().getFeatures())['value'], 9.9)

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

        self.assertEqual(next(ml.dataProvider().getFeatures())['value'], 9.9)
        self.assertEqual(next(ml.getFeatures())['value'], 9.9)

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

        self.assertEqual(next(ml.dataProvider().getFeatures())['value'], 10)

        # Check that we get a QgsEditError exception when the commit fails
        with self.assertRaises(QgsEditError):
            with edit(ml) as l:
                l.rollBack()