Running PyQGIS script on hundreds of layers

Question

I would like to repeat this script on hundreds of layers using PyQGIS 3.16.

I wanted to import it in the Modeler from the QGIS toolbox and then run the script in a batch process to select my hundreds of layers. The problem is that I can't switch from the Python console to the QGIS toolbox, I systematically get errors ("iface is not defined", "SyntaxError: (unicode error) 'utf8' codec can't decode byte 0x8e....") and I can't solve them... I also tried to make the script in the same table according to the attributes of a field "name" to repeat it when the name of the object changes but nothing happens using the function: "getFeature()" but the loop does not happen.

Would you have a solution?

from qgis.utils import iface
from PyQt5.QtCore import QVariant

layer = iface.activeLayer() #Click layer in layer tree
idfield = 'num_page_1' #Change to match the name of your field


coords = [[round(f.geometry().centroid().asPoint().x(),0),round(f.geometry().centroid().asPoint().y(),0),f.id()] for f in layer.getFeatures()]
coords.sort(key=lambda k: (k[1],-k[0]), reverse=True)
order = [i[2] for i in coords]

i = layer.fields().indexFromName(idfield)
attrMap = {id: {i:e} for e,id in enumerate(order,1)}
layer.dataProvider().changeAttributeValues(attrMap)

Answer 1

List the geopackages and layers like this:

import os
geopackage_folder = r'/home/bera/GIS/Data/testdata'

for item in os.listdir(geopackage_folder): #List everything in the folder above.
    fullname = os.path.join(geopackage_folder, item)
    if fullname.endswith('.gpkg'): #Find the geopackages
        print(item)

        #Process each geopackage layer
        layer = QgsVectorLayer(fullname,"test","ogr") #https://stackoverflow.com/questions/57015320/how-to-list-all-layers-on-geopackage-using-pyqgis
        subLayers = layer.dataProvider().subLayers()
        for subLayer in subLayers:
            name = subLayer.split('!!::!!')[1]
            print(name)
            uri = "%s|layername=%s" % (fullname, name,)
            subLayer = QgsVectorLayer(uri, name, 'ogr')
            
            #Do something with subLayer (one geopackage table) here