QGIS/python/plugins/processing/algs/qgis/Merge.py

# -*- coding: utf-8 -*-

"""
***************************************************************************
    Gridify.py
    ---------------------
    Date                 : May 2010
    Copyright            : (C) 2010 by Michael Minn
    Email                : pyqgis at michaelminn dot com
***************************************************************************
*                                                                         *
*   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 Minn'
__date__ = 'May 2010'
__copyright__ = '(C) 2010, Michael Minn'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

import os

from qgis.PyQt.QtGui import QIcon
from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsFields,
                       QgsField,
                       QgsFeatureRequest,
                       QgsFeatureSink,
                       QgsProcessingUtils,
                       QgsProcessingParameterMultipleLayers,
                       QgsProcessingParameterDefinition,
                       QgsProcessingParameterFeatureSink,
                       QgsProcessingOutputVectorLayer,
                       QgsMapLayer)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterMultipleInput
from processing.core.outputs import OutputVector
from processing.tools import dataobjects

pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]


class Merge(QgisAlgorithm):
    LAYERS = 'LAYERS'
    OUTPUT = 'OUTPUT'

    def icon(self):
        return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'merge_shapes.png'))

    def group(self):
        return self.tr('Vector general tools')

    def __init__(self):
        super().__init__()
        self.addParameter(QgsProcessingParameterMultipleLayers(self.LAYERS,
                                                               self.tr('Layers to merge'),
                                                               QgsProcessingParameterDefinition.TypeVectorAny))

        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Merged')))
        self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Merged')))

        self.input_layers = []
        self.fields = None
        self.add_layer_field = None
        self.add_path_field = None
        self.sink = None
        self.dest_id = None
        self.dest_crs = None

    def name(self):
        return 'mergevectorlayers'

    def displayName(self):
        return self.tr('Merge vector layers')

    def prepareAlgorithm(self, parameters, context, feedback):
        self.input_layers = self.parameterAsLayerList(parameters, self.LAYERS, context)
        layers = []
        self.fields = QgsFields()
        totalFeatureCount = 0
        for layer in self.input_layers:
            if layer.type() != QgsMapLayer.VectorLayer:
                raise GeoAlgorithmExecutionException(
                    self.tr('All layers must be vector layers!'))

            if (len(layers) > 0):
                if (layer.wkbType() != layers[0].wkbType()):
                    raise GeoAlgorithmExecutionException(
                        self.tr('All layers must have same geometry type!'))

            layers.append(layer)
            totalFeatureCount += layer.featureCount()

            for sindex, sfield in enumerate(layer.fields()):
                found = None
                for dfield in self.fields:
                    if (dfield.name().upper() == sfield.name().upper()):
                        found = dfield
                        if (dfield.type() != sfield.type()):
                            raise GeoAlgorithmExecutionException(
                                self.tr('{} field in layer {} has different '
                                        'data type than in other layers.'.format(sfield.name(), layerSource)))

                if not found:
                    self.fields.append(sfield)

        self.add_layer_field = False
        if self.fields.lookupField('layer') < 0:
            self.fields.append(QgsField('layer', QVariant.String, '', 100))
            self.add_layer_field = True
        self.add_path_field = False
        if self.fields.lookupField('path') < 0:
            self.fields.append(QgsField('path', QVariant.String, '', 200))
            self.add_path_field = True

        total = 100.0 / totalFeatureCount if totalFeatureCount else 1
        self.dest_crs = layers[0].crs()
        (self.sink, self.dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                                         self.fields, layers[0].wkbType(), self.dest_crs)
        return True

    def processAlgorithm(self, context, feedback):

        featureCount = 0
        for layer in self.layers:
            for feature in layer.getFeatures(QgsFeatureRequest().setDestinationCrs(self.dest_crs)):
                if feedback.isCanceled():
                    break

                sattributes = feature.attributes()
                dattributes = []
                for dindex, dfield in enumerate(self.fields):
                    if self.add_layer_field and dfield.name() == 'layer':
                        dattributes.append(layer.name())
                        continue
                    if self.add_path_field and dfield.name() == 'path':
                        dattributes.append(layer.publicSource())
                        continue

                    if (dfield.type() == QVariant.Int, QVariant.UInt, QVariant.LongLong, QVariant.ULongLong):
                        dattribute = 0
                    elif (dfield.type() == QVariant.Double):
                        dattribute = 0.0
                    else:
                        dattribute = ''

                    for sindex, sfield in enumerate(layer.fields()):
                        if (sfield.name().upper() == dfield.name().upper()):
                            if (sfield.type() != dfield.type()):
                                raise GeoAlgorithmExecutionException(
                                    self.tr('Attribute type mismatch'))
                            dattribute = sattributes[sindex]
                            break

                    dattributes.append(dattribute)

                feature.setAttributes(dattributes)
                self.sink.addFeature(feature, QgsFeatureSink.FastInsert)
                featureCount += 1
                feedback.setProgress(int(featureCount * self.total))
        return True

    def postProcessAlgorithm(self, context, feedback):
        return {self.OUTPUT: self.dest_id}