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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.
187 lines
7.5 KiB
Python
187 lines
7.5 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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FieldPyculator.py
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---------------------
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Date : August 2012
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Copyright : (C) 2012 by Victor Olaya
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Email : volayaf at gmail 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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from builtins import str
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__author__ = 'Victor Olaya & NextGIS'
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__date__ = 'August 2012'
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__copyright__ = '(C) 2012, Victor Olaya & NextGIS'
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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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import sys
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsFeature,
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QgsField,
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QgsFeatureSink,
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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 ParameterVector
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from processing.core.parameters import ParameterString
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from processing.core.parameters import ParameterNumber
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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 FieldsPyculator(QgisAlgorithm):
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INPUT_LAYER = 'INPUT_LAYER'
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FIELD_NAME = 'FIELD_NAME'
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FIELD_TYPE = 'FIELD_TYPE'
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FIELD_LENGTH = 'FIELD_LENGTH'
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FIELD_PRECISION = 'FIELD_PRECISION'
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GLOBAL = 'GLOBAL'
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FORMULA = 'FORMULA'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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RESULT_VAR_NAME = 'value'
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TYPES = [QVariant.Int, QVariant.Double, QVariant.String]
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def group(self):
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return self.tr('Vector table 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.type_names = [self.tr('Integer'),
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self.tr('Float'),
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self.tr('String')]
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self.addParameter(ParameterVector(self.INPUT_LAYER,
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self.tr('Input layer')))
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self.addParameter(ParameterString(self.FIELD_NAME,
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self.tr('Result field name'), 'NewField'))
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self.addParameter(ParameterSelection(self.FIELD_TYPE,
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self.tr('Field type'), self.type_names))
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self.addParameter(ParameterNumber(self.FIELD_LENGTH,
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self.tr('Field length'), 1, 255, 10))
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self.addParameter(ParameterNumber(self.FIELD_PRECISION,
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self.tr('Field precision'), 0, 10, 0))
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self.addParameter(ParameterString(self.GLOBAL,
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self.tr('Global expression'), multiline=True, optional=True))
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self.addParameter(ParameterString(self.FORMULA,
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self.tr('Formula'), 'value = ', multiline=True))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Calculated')))
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def name(self):
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return 'advancedpythonfieldcalculator'
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def displayName(self):
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return self.tr('Advanced Python field calculator')
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def processAlgorithm(self, parameters, context, feedback):
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fieldName = self.getParameterValue(self.FIELD_NAME)
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fieldType = self.getParameterValue(self.FIELD_TYPE)
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fieldLength = self.getParameterValue(self.FIELD_LENGTH)
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fieldPrecision = self.getParameterValue(self.FIELD_PRECISION)
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code = self.getParameterValue(self.FORMULA)
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globalExpression = self.getParameterValue(self.GLOBAL)
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output = self.getOutputFromName(self.OUTPUT_LAYER)
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layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_LAYER), context)
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fields = layer.fields()
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fields.append(QgsField(fieldName, self.TYPES[fieldType], '',
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fieldLength, fieldPrecision))
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writer = output.getVectorWriter(fields, layer.wkbType(), layer.crs(), context)
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outFeat = QgsFeature()
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new_ns = {}
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# Run global code
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if globalExpression.strip() != '':
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try:
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bytecode = compile(globalExpression, '<string>', 'exec')
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exec(bytecode, new_ns)
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except:
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raise GeoAlgorithmExecutionException(
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self.tr("FieldPyculator code execute error.Global code block can't be executed!\n{0}\n{1}").format(str(sys.exc_info()[0].__name__), str(sys.exc_info()[1])))
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# Replace all fields tags
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fields = layer.fields()
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num = 0
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for field in fields:
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field_name = str(field.name())
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replval = '__attr[' + str(num) + ']'
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code = code.replace('<' + field_name + '>', replval)
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num += 1
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# Replace all special vars
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code = code.replace('$id', '__id')
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code = code.replace('$geom', '__geom')
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need_id = code.find('__id') != -1
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need_geom = code.find('__geom') != -1
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need_attrs = code.find('__attr') != -1
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# Compile
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try:
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bytecode = compile(code, '<string>', 'exec')
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except:
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raise GeoAlgorithmExecutionException(
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self.tr("FieldPyculator code execute error. Field code block can't be executed!\n{0}\n{1}").format(str(sys.exc_info()[0].__name__), str(sys.exc_info()[1])))
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# Run
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features = QgsProcessingUtils.getFeatures(layer, context)
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total = 100.0 / layer.featureCount() if layer.featureCount() else 0
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for current, feat in enumerate(features):
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feedback.setProgress(int(current * total))
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attrs = feat.attributes()
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feat_id = feat.id()
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# Add needed vars
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if need_id:
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new_ns['__id'] = feat_id
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if need_geom:
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geom = feat.geometry()
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new_ns['__geom'] = geom
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if need_attrs:
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pyattrs = [a for a in attrs]
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new_ns['__attr'] = pyattrs
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# Clear old result
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if self.RESULT_VAR_NAME in new_ns:
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del new_ns[self.RESULT_VAR_NAME]
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# Exec
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exec(bytecode, new_ns)
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# Check result
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if self.RESULT_VAR_NAME not in new_ns:
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raise GeoAlgorithmExecutionException(
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self.tr("FieldPyculator code execute error\n"
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"Field code block does not return '{0}' variable! "
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"Please declare this variable in your code!").format(self.RESULT_VAR_NAME))
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# Write feature
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outFeat.setGeometry(feat.geometry())
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attrs.append(new_ns[self.RESULT_VAR_NAME])
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outFeat.setAttributes(attrs)
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writer.addFeature(outFeat, QgsFeatureSink.FastInsert)
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del writer
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def checkParameterValues(self, parameters, context):
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# TODO check that formula is correct and fields exist
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return super(FieldsPyculator, self).checkParameterValues(parameters, context)
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