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a05d941e4e
Since the underlying issues with the Python bindings are now fixed, in most cases we can safely default to allowing an algorithm to run in a background thread!! So now we make this the default, and require individual algorithms which are NOT thread safe to declare this. This includes algorithms which directly manipulate the current project or layers (such as setting layer styles), alter the selections in layers, or which rely on 3rd party libraries (for now, SAGA and GRASS algorithms are marked as not thread safe... TODO - someone more familiar with these libraries can investigate and remove the flag if appropriate). Also models are marked as non-thread safe. TODO: only flag an individual model as thread-unsafe if any of its child algorithms report this flag.
146 lines
5.6 KiB
Python
146 lines
5.6 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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SelectByAttribute.py
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---------------------
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Date : May 2010
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Copyright : (C) 2010 by Michael Minn
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Email : pyqgis at michaelminn dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = 'Michael Minn'
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__date__ = 'May 2010'
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__copyright__ = '(C) 2010, Michael Minn'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsExpression,
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QgsProcessingException,
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QgsProcessingAlgorithm,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterField,
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QgsProcessingParameterEnum,
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QgsProcessingParameterString,
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QgsProcessingOutputVectorLayer)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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class SelectByAttribute(QgisAlgorithm):
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INPUT = 'INPUT'
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FIELD = 'FIELD'
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OPERATOR = 'OPERATOR'
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VALUE = 'VALUE'
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OUTPUT = 'OUTPUT'
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OPERATORS = ['=',
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'!=',
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'>',
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'>=',
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'<',
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'<=',
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'begins with',
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'contains',
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'is null',
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'is not null',
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'does not contain'
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]
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STRING_OPERATORS = ['begins with',
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'contains',
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'does not contain']
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def tags(self):
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return self.tr('select,attribute,value,contains,null,field').split(',')
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def group(self):
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return self.tr('Vector selection')
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def groupId(self):
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return 'vectorselection'
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def __init__(self):
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super().__init__()
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def flags(self):
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return super().flags() | QgsProcessingAlgorithm.FlagNoThreading
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def initAlgorithm(self, config=None):
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self.i18n_operators = ['=',
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'!=',
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'>',
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'>=',
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'<',
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'<=',
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self.tr('begins with'),
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self.tr('contains'),
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self.tr('is null'),
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self.tr('is not null'),
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self.tr('does not contain')
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]
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self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT, self.tr('Input layer')))
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self.addParameter(QgsProcessingParameterField(self.FIELD,
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self.tr('Selection attribute'), parentLayerParameterName=self.INPUT))
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self.addParameter(QgsProcessingParameterEnum(self.OPERATOR,
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self.tr('Operator'), self.i18n_operators))
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self.addParameter(QgsProcessingParameterString(self.VALUE, self.tr('Value')))
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self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Selected (attribute)')))
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def name(self):
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return 'selectbyattribute'
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def displayName(self):
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return self.tr('Select by attribute')
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def processAlgorithm(self, parameters, context, feedback):
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layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
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fieldName = self.parameterAsString(parameters, self.FIELD, context)
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operator = self.OPERATORS[self.parameterAsEnum(parameters, self.OPERATOR, context)]
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value = self.parameterAsString(parameters, self.VALUE, context)
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fields = layer.fields()
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idx = layer.fields().lookupField(fieldName)
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fieldType = fields[idx].type()
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if fieldType != QVariant.String and operator in self.STRING_OPERATORS:
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op = ''.join(['"%s", ' % o for o in self.STRING_OPERATORS])
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raise QgsProcessingException(
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self.tr('Operators {0} can be used only with string fields.').format(op))
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field_ref = QgsExpression.quotedColumnRef(fieldName)
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quoted_val = QgsExpression.quotedValue(value)
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if operator == 'is null':
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expression_string = '{} IS NULL'.format(field_ref)
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elif operator == 'is not null':
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expression_string = '{} IS NOT NULL'.format(field_ref)
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elif operator == 'begins with':
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expression_string = """%s LIKE '%s%%'""" % (field_ref, value)
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elif operator == 'contains':
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expression_string = """%s LIKE '%%%s%%'""" % (field_ref, value)
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elif operator == 'does not contain':
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expression_string = """%s NOT LIKE '%%%s%%'""" % (field_ref, value)
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else:
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expression_string = '{} {} {}'.format(field_ref, operator, quoted_val)
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expression = QgsExpression(expression_string)
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if expression.hasParserError():
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raise QgsProcessingException(expression.parserErrorString())
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layer.selectByExpression(expression_string)
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return {self.OUTPUT: parameters[self.INPUT]}
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