I want to create a custom processing tool for geocoding in QGIS.
It will reproduce the "Batch Nominatim geocoder" geoalgorithm, besides several things:
- another URL of a geocoder will be used instead of the the Nominatim
- there will be no limitations in requests
From the "Batch Nominatim geocoder" I would like to inherit: GUI, functionality and logic.
I tried to create a model in the Graphical Modeler and export it as a Python Processing Script, however it does not look like what I need.
"""
Model exported as python.
Name : geocoding
Group : STMA
With QGIS : 32205
"""
from qgis.core import QgsProcessing
from qgis.core import QgsProcessingAlgorithm
from qgis.core import QgsProcessingMultiStepFeedback
from qgis.core import QgsProcessingParameterVectorLayer
from qgis.core import QgsProcessingParameterFeatureSink
import processing
class Geocoding(QgsProcessingAlgorithm):
def initAlgorithm(self, config=None):
self.addParameter(QgsProcessingParameterVectorLayer('Adressen', 'adressen', types=[QgsProcessing.TypeVector], defaultValue=None))
self.addParameter(QgsProcessingParameterFeatureSink('Geocodiert', 'geocodiert', type=QgsProcessing.TypeVectorAnyGeometry, createByDefault=True, supportsAppend=True, defaultValue=None))
def processAlgorithm(self, parameters, context, model_feedback):
# Use a multi-step feedback, so that individual child algorithm progress reports are adjusted for the
# overall progress through the model
feedback = QgsProcessingMultiStepFeedback(1, model_feedback)
results = {}
outputs = {}
# Batch Nominatim geocoder
alg_params = {
'FIELD': 'Anschrift',
'INPUT': parameters['Adressen'],
'OUTPUT': parameters['Geocodiert']
}
outputs['BatchNominatimGeocoder'] = processing.run('native:batchnominatimgeocoder', alg_params, context=context, feedback=feedback, is_child_algorithm=True)
results['Geocodiert'] = outputs['BatchNominatimGeocoder']['OUTPUT']
return results
def name(self):
return 'geocoding'
def displayName(self):
return 'geocoding'
def group(self):
return 'STMA'
def groupId(self):
return ''
def createInstance(self):
return Geocoding()
I could find this geoalgorithm in QGIS/src/core/geocoding/qgsnominatimgeocoder.cpp on the GitHub. This is the part with an URL:
QgsNominatimGeocoder::QgsNominatimGeocoder( const QString &countryCodes, const QString &endpoint )
: QgsGeocoderInterface()
, mCountryCodes( countryCodes )
, mEndpoint( QStringLiteral( "https://nominatim.qgis.org/search" ) )
But C++ is simply beyond my programming skills.
Another (maybe a feasible) solution is to reproduce the "Google Maps Geocoder" plugin developed by @ndawson. It is basically a processing tool, similar to "Batch Nominatim geocoder" but implemented for Google Maps. This plugin is available on the GitHub: https://github.com/north-road/qgis-google-maps-geocoder. Unfortunately the geocoding in this plugin is dependent on the QgsGoogleMapsGeocoder class, not a simple request to Google Maps API.
What are my available approaches?
Perhaps it is in general impossible because I simply collide with copyrights of the core developer (Mathieu Pellerin @nirvn).
