mirror of
https://github.com/qgis/QGIS.git
synced 2025-04-09 00:05:52 -04:00
1e13d733c2
initAlgorithm() method This allows 2 benefits: - algorithms can be subclassed and have subclasses add additional parameters/outputs to the algorithm. With the previous approach of declaring parameters/outputs in the constructor, it's not possible to call virtual methods to add additional parameters/ outputs (since you can't call virtual methods from a constructor). - initAlgorithm takes a variant map argument, allowing the algorithm to dynamically adjust its declared parameters and outputs according to this configuration map. This potentially allows model algorithms which can be configured to have variable numbers of parameters and outputs at run time. E.g. a "router" algorithm which directs features to one of any number of output sinks depending on some user configured criteria.
92 lines
3.6 KiB
Python
92 lines
3.6 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
"""
|
|
***************************************************************************
|
|
SelectByExpression.py
|
|
---------------------
|
|
Date : July 2014
|
|
Copyright : (C) 2014 by Michael Douchin
|
|
***************************************************************************
|
|
* *
|
|
* 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__ = 'Michael Douchin'
|
|
__date__ = 'July 2014'
|
|
__copyright__ = '(C) 2014, Michael Douchin'
|
|
|
|
# This will get replaced with a git SHA1 when you do a git archive
|
|
|
|
__revision__ = '$Format:%H$'
|
|
|
|
from qgis.core import (QgsExpression,
|
|
QgsVectorLayer,
|
|
QgsProcessingParameterVectorLayer,
|
|
QgsProcessingParameterExpression,
|
|
QgsProcessingParameterEnum,
|
|
QgsProcessingOutputVectorLayer)
|
|
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
|
|
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
|
|
|
|
|
|
class SelectByExpression(QgisAlgorithm):
|
|
|
|
INPUT = 'INPUT'
|
|
EXPRESSION = 'EXPRESSION'
|
|
OUTPUT = 'OUTPUT'
|
|
METHOD = 'METHOD'
|
|
|
|
def group(self):
|
|
return self.tr('Vector selection tools')
|
|
|
|
def __init__(self):
|
|
super().__init__()
|
|
|
|
def initAlgorithm(self, config=None):
|
|
self.methods = [self.tr('creating new selection'),
|
|
self.tr('adding to current selection'),
|
|
self.tr('removing from current selection'),
|
|
self.tr('selecting within current selection')]
|
|
|
|
self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT, self.tr('Input layer')))
|
|
|
|
self.addParameter(QgsProcessingParameterExpression(self.EXPRESSION,
|
|
self.tr('Expression'), parentLayerParameterName=self.INPUT))
|
|
self.addParameter(QgsProcessingParameterEnum(self.METHOD,
|
|
self.tr('Modify current selection by'), self.methods, 0))
|
|
|
|
self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Selected (attribute)')))
|
|
|
|
def name(self):
|
|
return 'selectbyexpression'
|
|
|
|
def displayName(self):
|
|
return self.tr('Select by expression')
|
|
|
|
def processAlgorithm(self, parameters, context, feedback):
|
|
layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
|
|
|
|
method = self.parameterAsEnum(parameters, self.METHOD, context)
|
|
|
|
if method == 0:
|
|
behavior = QgsVectorLayer.SetSelection
|
|
elif method == 1:
|
|
behavior = QgsVectorLayer.AddToSelection
|
|
elif method == 2:
|
|
behavior = QgsVectorLayer.RemoveFromSelection
|
|
elif method == 3:
|
|
behavior = QgsVectorLayer.IntersectSelection
|
|
|
|
expression = self.parameterAsString(parameters, self.EXPRESSION, context)
|
|
qExp = QgsExpression(expression)
|
|
if qExp.hasParserError():
|
|
raise GeoAlgorithmExecutionException(qExp.parserErrorString())
|
|
|
|
layer.selectByExpression(expression, behavior)
|
|
return {self.OUTPUT: parameters[self.INPUT]}
|