PyQGIS - Adding layer from PostGis database on QGIS interface

Question

I have the same problem, bellow my code if some one can help me please.

from qgis.core import *
from qgis.core import QgsProject
from PyQt5.QtCore import QFileInfo
from qgis.core import QgsVectorLayer, QgsDataSourceUri
def run_script(iface):
 uri = QgsDataSourceUri()
 uri.setConnection("localhost", "5432", "Base_test", "user", "****")
 uri.setDataSource("public", "mytable", "geom","")
 vlayer = QgsVectorLayer(uri.uri(), "mytable", "user")
 QgsMapLayerRegistry.instance().addMapLayers([layer])

When I run this code I haven't un error but i see nothing on my QGIS interface.

I'm using, QGIS 3.12.

---

from qgis.core import *
from qgis.core import QgsProject
from PyQt5.QtCore import QFileInfo
from qgis.core import QgsVectorLayer, QgsDataSourceUri
from qgis.utils import *
import processing
def run_script(iface):
 uri = QgsDataSourceUri()
 uri.setConnection("localhost", "5432", "Base_test", "Nassim", "*****")
 uri.setDataSource("public", "BPE", "geom")
 layer = QgsVectorLayer(uri.uri(), "BPE", "Nassim")
 QgsProject.instance().addMapLayer(layer)

This is my code whith the solution given by @Vincent Bré, but it still doesn't work

• PolyGeo: You say that you "have the same problem" but the same problem as what?
• ThomasG77: Did you run run_script(iface)? It's because all the code you show us is only declaring the function but you need to call it to work
• nmokht97: Sorry PolyGeo, I juste made un copy past from an other post, my problème it's: i can't display my layer on QGIS interface whene I load it from Postgis DB
• nmokht97: I have a new problem now, this solution seems working but it bug my QGIS app and i need to restart it.

Answer 1

You should use QgsProject instead of QgsMapLayerRegistry.

To add a single layer, you can use the addMapLayer method.

You can use the following code:

uriPG = QgsDataSourceUri()
uriPG.setConnection("localhost", "5432", "database", "user", "password")
uriPG.setDataSource("schema", "name_table", "geometry_column")
layer = QgsVectorLayer(uriPG.uri(), "name_table_in_qgis", "user")
QgsProject.instance().addMapLayer(layer)

• nmokht97: Thank you for your answser, it stil not working for me. I don't know why besacuse it's excatlty you code what I put whith the good parameters .in addition, it makes my QGIS buggy and you have to relaunch it
• Vincent Bré: Do you have an error message?
• nmokht97: no error message
• Vincent Bré: My code works. You run it from the Python console in QGIS? Make sure you check the name of your table, the geometry column
• nmokht97: >>>exec(open('C:/Users/NASSIM~1.MOK/AppData/Local/Temp/tmpmv2m58vg.py'.encode('utf-8')).read())

Answer 2

I made a modification on layer = QgsVectorLayer(uri.uri(), "BPE", "") removing the user in this function, what stope the bug, I'm sure of my parameters because when I load the same table frome postgis using the interface all is ok. but whene I'm using Pyqgis it give me "unusing layer"

uriPG = QgsDataSourceUri()
uriPG.setConnection("localhost", "5432", "Base_test", "Nassim", "******")
uriPG.setDataSource("public", "CABLES", "geom")
layer = QgsVectorLayer(uriPG.uri(), "BPE",)
if not layer.isValid():
 print("Layer %s did not load" %layer.name()) 

QgsProject.instance().addMapLayer(layer)

bellow the picture of my result in the console and QGIS interface

it gives " an using layer"

enter image description here

• nmokht97: I fixed my problem, I juste changed in 'code'layer = QgsVectorLayer(uriPG.uri(), "BPE","postgres") , I don't use my own user here.