From f3dd5150c75311afdf79fd590e66c422df5ece7b Mon Sep 17 00:00:00 2001
From: Matthias Kuhn <matthias@opengis.ch>
Date: Sun, 6 Oct 2019 10:55:18 +0200
Subject: [PATCH] [db_manager] Detect CRS in advanced add layer

---
 .../plugins/db_manager/db_plugins/plugin.py   |  9 ++++++++-
 .../db_plugins/postgis/connector.py           | 19 ++++++++++++++++++-
 .../db_manager/db_plugins/postgis/plugin.py   |  3 +++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/python/plugins/db_manager/db_plugins/plugin.py b/python/plugins/db_manager/db_plugins/plugin.py
index 071cd8b2506..aff34afe651 100644
--- a/python/plugins/db_manager/db_plugins/plugin.py
+++ b/python/plugins/db_manager/db_plugins/plugin.py
@@ -52,7 +52,8 @@ from qgis.core import (
     QgsVectorLayer,
     QgsRasterLayer,
     QgsProject,
-    QgsMessageLog
+    QgsMessageLog,
+    QgsCoordinateReferenceSystem
 )
 
 from qgis.gui import (
@@ -745,6 +746,11 @@ class Table(DbItemObject):
         uri.setDataSource(schema, self.name, geomCol if geomCol else None, None, uniqueCol.name if uniqueCol else "")
         return uri
 
+    def crs(self):
+        """Returns the CRS of this table or an invalid CRS if this is not a spatial table
+        This should be overwritten by any additional db plugins"""
+        return QgsCoordinateReferenceSystem()
+
     def mimeUri(self):
         layerType = "raster" if self.type == Table.RasterType else "vector"
         return u"%s:%s:%s:%s" % (layerType, self.database().dbplugin().providerName(), self.name, self.uri().uri(False))
@@ -1144,6 +1150,7 @@ class VectorTable(Table):
         layout.addRow(zCheckBox)
         layout.addRow(mCheckBox)
         crsSelector = QgsProjectionSelectionWidget()
+        crsSelector.setCrs(self.crs())
         layout.addRow(self.tr('CRS'), crsSelector)
 
         def selectedGeometryType():
diff --git a/python/plugins/db_manager/db_plugins/postgis/connector.py b/python/plugins/db_manager/db_plugins/postgis/connector.py
index e88af5b9bf0..4bf83b4c83c 100644
--- a/python/plugins/db_manager/db_plugins/postgis/connector.py
+++ b/python/plugins/db_manager/db_plugins/postgis/connector.py
@@ -27,7 +27,7 @@ from builtins import range
 from functools import cmp_to_key
 
 from qgis.PyQt.QtCore import QRegExp, QFile, QCoreApplication
-from qgis.core import Qgis, QgsCredentials, QgsDataSourceUri
+from qgis.core import Qgis, QgsCredentials, QgsDataSourceUri, QgsCoordinateReferenceSystem
 
 from ..connector import DBConnector
 from ..plugin import ConnectionError, DbError, Table
@@ -642,6 +642,23 @@ class PostGisDBConnector(DBConnector):
         self._close_cursor(c)
         return res[0] if res is not None else None
 
+    def getCrs(self, srid):
+        if not self.has_spatial:
+            return QgsCoordinateReferenceSystem()
+
+        try:
+            c = self._execute(None, "SELECT proj4text FROM spatial_ref_sys WHERE srid = '%d'" % srid)
+        except DbError:
+            return QgsCoordinateReferenceSystem()
+        res = self._fetchone(c)
+        self._close_cursor(c)
+        if res is None:
+            return QgsCoordinateReferenceSystem()
+
+        proj4text = res[0]
+        crs = QgsCoordinateReferenceSystem.fromProj4(proj4text)
+        return crs
+
     def getSpatialRefInfo(self, srid):
         if not self.has_spatial:
             return
diff --git a/python/plugins/db_manager/db_plugins/postgis/plugin.py b/python/plugins/db_manager/db_plugins/postgis/plugin.py
index 0a1bc85492b..26471120db6 100644
--- a/python/plugins/db_manager/db_plugins/postgis/plugin.py
+++ b/python/plugins/db_manager/db_plugins/postgis/plugin.py
@@ -269,6 +269,9 @@ class PGTable(Table):
 
         return PGTableInfo(self)
 
+    def crs(self):
+        return self.database().connector.getCrs(self.srid)
+
     def tableDataModel(self, parent):
         from .data_model import PGTableDataModel