Attach QgsSourceSelectProviderRegistry to QgsGui

And make it a singleton

python/gui/qgsgui.sip

@@ -38,6 +38,12 @@ class QgsGui
  :rtype: QgsEditorWidgetRegistry
 %End
 
+    static QgsSourceSelectProviderRegistry *sourceSelectProviderRegistry();
+%Docstring
+ Returns the global source select provider registry, used for managing all known source select widget factories.
+ :rtype: QgsSourceSelectProviderRegistry
+%End
+
     static QgsShortcutsManager *shortcutsManager();
 %Docstring
  Returns the global shortcuts manager, used for managing a QAction and QShortcut sequences.

python/gui/qgssourceselectproviderregistry.sip

@@ -14,6 +14,9 @@ class QgsSourceSelectProviderRegistry
  This class keeps a list of source select providers that may add items to the QgsDataSourceManagerDialog
  When created, it automatically adds providers from data provider plugins (e.g. PostGIS, WMS, ...)
 
+ QgsSourceSelectProviderRegistry is not usually directly created, but rather accessed through
+ QgsGui.sourceSelectProviderRegistry().
+
 .. versionadded:: 3.0
 %End
 

src/gui/qgsgui.cpp

@@ -19,6 +19,7 @@
 #include "qgseditorwidgetregistry.h"
 #include "qgslayertreeembeddedwidgetregistry.h"
 #include "qgsmaplayeractionregistry.h"
+#include "qgssourceselectproviderregistry.h"
 #include "qgslayoutitemregistry.h"
 #include "qgslayoutitemguiregistry.h"
 #include "qgslayoutviewrubberband.h"
@@ -45,6 +46,11 @@ QgsEditorWidgetRegistry *QgsGui::editorWidgetRegistry()
   return instance()->mEditorWidgetRegistry;
 }
 
+QgsSourceSelectProviderRegistry *QgsGui::sourceSelectProviderRegistry()
+{
+  return instance()->mSourceSelectProviderRegistry;
+}
+
 QgsShortcutsManager *QgsGui::shortcutsManager()
 {
   return instance()->mShortcutsManager;
@@ -71,6 +77,7 @@ QgsGui::~QgsGui()
   delete mLayerTreeEmbeddedWidgetRegistry;
   delete mEditorWidgetRegistry;
   delete mMapLayerActionRegistry;
+  delete mSourceSelectProviderRegistry;
   delete mShortcutsManager;
   delete mNative;
 }
@@ -87,6 +94,7 @@ QgsGui::QgsGui()
   mShortcutsManager = new QgsShortcutsManager();
   mLayerTreeEmbeddedWidgetRegistry = new QgsLayerTreeEmbeddedWidgetRegistry();
   mMapLayerActionRegistry = new QgsMapLayerActionRegistry();
+  mSourceSelectProviderRegistry = new QgsSourceSelectProviderRegistry();
   mLayoutItemGuiRegistry = new QgsLayoutItemGuiRegistry();
   mLayoutItemGuiRegistry->populate();
 }

src/gui/qgsgui.h

@@ -25,6 +25,7 @@ class QgsEditorWidgetRegistry;
 class QgsShortcutsManager;
 class QgsLayerTreeEmbeddedWidgetRegistry;
 class QgsMapLayerActionRegistry;
+class QgsSourceSelectProviderRegistry;
 class QgsNative;
 class QgsLayoutItemGuiRegistry;
 
@@ -61,6 +62,11 @@ class GUI_EXPORT QgsGui
      */
     static QgsEditorWidgetRegistry *editorWidgetRegistry();
 
+    /**
+     * Returns the global source select provider registry, used for managing all known source select widget factories.
+     */
+    static QgsSourceSelectProviderRegistry *sourceSelectProviderRegistry();
+
     /**
      * Returns the global shortcuts manager, used for managing a QAction and QShortcut sequences.
      */
@@ -89,6 +95,7 @@ class GUI_EXPORT QgsGui
 
     QgsNative *mNative = nullptr;
     QgsEditorWidgetRegistry *mEditorWidgetRegistry = nullptr;
+    QgsSourceSelectProviderRegistry *mSourceSelectProviderRegistry = nullptr;
     QgsShortcutsManager *mShortcutsManager = nullptr;
     QgsLayerTreeEmbeddedWidgetRegistry *mLayerTreeEmbeddedWidgetRegistry = nullptr;
     QgsMapLayerActionRegistry *mMapLayerActionRegistry = nullptr;

src/gui/qgssourceselectproviderregistry.h

@@ -25,6 +25,9 @@ class QgsSourceSelectProvider;
  * This class keeps a list of source select providers that may add items to the QgsDataSourceManagerDialog
  * When created, it automatically adds providers from data provider plugins (e.g. PostGIS, WMS, ...)
  *
+ * QgsSourceSelectProviderRegistry is not usually directly created, but rather accessed through
+ * QgsGui::sourceSelectProviderRegistry().
+ *
  * \since QGIS 3.0
  */
 class GUI_EXPORT QgsSourceSelectProviderRegistry

tests/src/python/test_qgssourceselectprovider.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 """
-Test the QgsSourceSelectProvider class
+Test the QgsSourceSelectProvider 
+and QgsSourceSelectProviderRegistry classes
 
 Run with: ctest -V -R PyQgsSourceSelectProvider
 
@@ -12,7 +13,7 @@
 
 import os
 import tempfile
-from qgis.gui import (QgsSourceSelectProvider, QgsSourceSelectProviderRegistry, QgsAbstractDataSourceWidget)
+from qgis.gui import (QgsGui, QgsSourceSelectProvider, QgsSourceSelectProviderRegistry, QgsAbstractDataSourceWidget)
 from qgis.testing import start_app, unittest
 from qgis.PyQt.QtGui import QIcon
 from qgis.PyQt.QtWidgets import QWidget
@@ -90,9 +91,8 @@ def testConcreteClass(self):
         self.assertEqual(provider.ordering(), 1)
         self.assertTrue(isinstance(provider.icon(), QIcon))
 
-    def testRegistry(self):
+    def _testRegistry(self, registry):
 
-        registry = QgsSourceSelectProviderRegistry()
         registry.addProvider(ConcreteSourceSelectProvider())
         registry.addProvider(ConcreteSourceSelectProvider2())
 
@@ -113,13 +113,21 @@ def testRegistry(self):
         # Get not existent by name
         self.assertFalse(registry.providerByName('Oh This Is Missing!'))
 
-        # Get providers by provider key
+        # Get providers by data provider key
         self.assertGreater(len(registry.providersByKey('MyTestProviderKey')), 0)
         self.assertGreater(len(registry.providersByKey('MyTestProviderKey2')), 0)
 
         # Get not existent by key
         self.assertEqual(len(registry.providersByKey('Oh This Is Missing!')), 0)
 
+    def testRegistry(self):
+        registry = QgsSourceSelectProviderRegistry()
+        self._testRegistry(registry)
+
+    def testRegistrySingleton(self):
+        registry = QgsGui.sourceSelectProviderRegistry()
+        self._testRegistry(registry)
+
 
 if __name__ == '__main__':
     unittest.main()