Using iface in standalone PyQGIS script

Question

I am practicing QGIS python API and I made a standalone script to create .qgs file and import some layers from PostGIS database. Now I need to zoom to imported layer but I saw that it is not possible via iface.setActiveLayer(vlayer) and then iface.zoomToActiveLayer() because I cannot use iface for standalone script.

Is there any other way to zoom to an imported layer?

This is what I have done so far:

import subprocess
subprocess.call([r'batch.bat'])
import qgis.core
print('Importovan')
import glob
import os
import sys
from qgis.core import (QgsProject, QgsRasterLayer,QgsVectorLayer,QgsApplication,QgsCoordinateReferenceSystem)
from qgis.gui import QgisInterface,QgsMapCanvas
from PyQt5.QtCore import QFileInfo
from PyQt5.QtSql import *
from qgis.core import QgsDataSourceUri
import qgis.utils
strProjectName = "my_project.qgs"
# start the qgis application
QgsApplication.setPrefixPath(r"C:\OSGeo4W64\apps\qgis", True)
qgs = QgsApplication([], False)
qgs.initQgis()
# start a project
project = QgsProject.instance()
selectedcrs="EPSG:4326"
target_crs = QgsCoordinateReferenceSystem()
target_crs.createFromUserInput(selectedcrs)
project.setCrs(target_crs)
canvas=QgsMapCanvas()
iface=QgisInterface.QgsMapCanvas()
project_path = strProjectName
###############################
db = QSqlDatabase.addDatabase('QPSQL')
# check to see if it is valid
if db.isValid():
 print ("QPSQL db is valid")
 # set the parameters needed for the connection
 db.setHostName('localhost')
 db.setDatabaseName('request')
 db.setPort(int(5433))
 db.setUserName('postgres')
 db.setPassword('postgres')
 uri = QgsDataSourceUri()
 uri.setConnection("localhost", "5433", "request", "postgres", "postgres")
 #open (create) the connection
 if db.open():
 print ("Opened %s" % uri.uri())
 uri.setDataSource ("rodno_razvrstani_podaci", 'statistika_2017', 'wkb_geometry')
 vlayer=QgsVectorLayer (uri .uri(False), 'statistika_2017', "postgres")
 project.addMapLayer(vlayer)
 
 else:
 err = db.lastError()
 print (err.driverText())
db.close()
#This is where script breaks
qgis.utils.iface.setActiveLayer(vlayer)
#iface.zoomToActiveLayer()
###############################
# write the project file
project.write(project_path)
# stop qgis
qgs.exitQgis() 

Answer 1

You don't need iface to zoom to a layer. It's sufficient to set the map canvas extent as the layer extent.

...
canvas.setExtent(vlayer.extent()) 
project.write(project_path)