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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.
159 lines
6.5 KiB
Python
159 lines
6.5 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ExecuteSQL.py -- use virtual layers to execute SQL on any sources
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---------------------
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Date : Jan 2016
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Copyright : (C) 2016 by Hugo Mercier
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Email : hugo dot mercier at oslandia 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__ = 'Hugo Mercier'
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__date__ = 'January 2016'
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__copyright__ = '(C) 2016, Hugo Mercier'
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# This will get replaced with a git SHA1 when you do a git archive323
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__revision__ = '$Format:%H$'
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from qgis.core import (QgsFeature,
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QgsVirtualLayerDefinition,
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QgsVectorLayer,
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QgsCoordinateReferenceSystem,
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QgsWkbTypes,
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QgsApplication,
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QgsProcessingUtils)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import ParameterString
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from processing.core.parameters import ParameterMultipleInput
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from processing.core.parameters import ParameterCrs
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from processing.core.parameters import ParameterSelection
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from processing.core.outputs import OutputVector
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class ExecuteSQL(QgisAlgorithm):
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""" This algorithm allows executing an SQL query on a set of input
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vector layers thanks to the virtual layer provider
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"""
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INPUT_DATASOURCES = 'INPUT_DATASOURCES'
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INPUT_QUERY = 'INPUT_QUERY'
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INPUT_UID_FIELD = 'INPUT_UID_FIELD'
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INPUT_GEOMETRY_FIELD = 'INPUT_GEOMETRY_FIELD'
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INPUT_GEOMETRY_TYPE = 'INPUT_GEOMETRY_TYPE'
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INPUT_GEOMETRY_CRS = 'INPUT_GEOMETRY_CRS'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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def group(self):
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return self.tr('Vector general tools')
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def __init__(self):
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super().__init__()
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def initAlgorithm(self, config=None):
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self.addParameter(ParameterMultipleInput(name=self.INPUT_DATASOURCES,
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description=self.tr('Additional input datasources (called input1, .., inputN in the query)'),
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optional=True))
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self.addParameter(ParameterString(name=self.INPUT_QUERY,
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description=self.tr('SQL query'),
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multiline=True))
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self.addParameter(ParameterString(name=self.INPUT_UID_FIELD,
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description=self.tr('Unique identifier field'), optional=True))
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self.addParameter(ParameterString(name=self.INPUT_GEOMETRY_FIELD,
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description=self.tr('Geometry field'), optional=True))
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self.geometryTypes = [
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self.tr('Autodetect'),
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self.tr('No geometry'),
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'Point',
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'LineString',
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'Polygon',
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'MultiPoint',
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'MultiLineString',
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'MultiPolygon']
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self.addParameter(ParameterSelection(self.INPUT_GEOMETRY_TYPE,
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self.tr('Geometry type'), self.geometryTypes, optional=True))
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self.addParameter(ParameterCrs(self.INPUT_GEOMETRY_CRS,
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self.tr('CRS'), optional=True))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('SQL Output')))
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def name(self):
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return 'executesql'
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def displayName(self):
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return self.tr('Execute SQL')
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def processAlgorithm(self, parameters, context, feedback):
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layers = self.getParameterValue(self.INPUT_DATASOURCES)
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query = self.getParameterValue(self.INPUT_QUERY)
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uid_field = self.getParameterValue(self.INPUT_UID_FIELD)
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geometry_field = self.getParameterValue(self.INPUT_GEOMETRY_FIELD)
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geometry_type = self.getParameterValue(self.INPUT_GEOMETRY_TYPE)
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geometry_crs = self.getParameterValue(self.INPUT_GEOMETRY_CRS)
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df = QgsVirtualLayerDefinition()
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layerIdx = 1
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if layers:
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for layerSource in layers.split(';'):
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layer = QgsProcessingUtils.mapLayerFromString(layerSource, context)
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if layer:
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df.addSource('input{}'.format(layerIdx), layer.id())
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layerIdx += 1
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if query == '':
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raise GeoAlgorithmExecutionException(
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self.tr('Empty SQL. Please enter valid SQL expression and try again.'))
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else:
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df.setQuery(query)
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if uid_field:
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df.setUid(uid_field)
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if geometry_type == 1: # no geometry
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df.setGeometryWkbType(QgsWkbTypes.NullGeometry)
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else:
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if geometry_field:
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df.setGeometryField(geometry_field)
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if geometry_type > 1:
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df.setGeometryWkbType(geometry_type - 1)
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if geometry_crs:
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crs = QgsCoordinateReferenceSystem(geometry_crs)
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if crs.isValid():
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df.setGeometrySrid(crs.postgisSrid())
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vLayer = QgsVectorLayer(df.toString(), "temp_vlayer", "virtual")
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if not vLayer.isValid():
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raise GeoAlgorithmExecutionException(vLayer.dataProvider().error().message())
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writer = self.getOutputFromName(self.OUTPUT_LAYER).getVectorWriter(vLayer.fields(),
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vLayer.wkbType() if geometry_type != 1 else 1,
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vLayer.crs(), context)
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features = QgsProcessingUtils.getFeatures(vLayer, context)
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total = 100.0 / vLayer.featureCount() if vLayer.featureCount() else 0
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outFeat = QgsFeature()
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for current, inFeat in enumerate(features):
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outFeat.setAttributes(inFeat.attributes())
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if geometry_type != 1:
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outFeat.setGeometry(inFeat.geometry())
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writer.addFeature(outFeat, QgsFeatureSink.FastInsert)
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feedback.setProgress(int(current * total))
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del writer
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