From 61812648a39f0be4554ade766f9ab87d40fb30a1 Mon Sep 17 00:00:00 2001
From: Matthias Kuhn <matthias@opengis.ch>
Date: Wed, 18 Sep 2019 09:31:22 +0200
Subject: [PATCH] Add API to hook into resolveReferences

---
 python/core/auto_generated/qgsmaplayer.sip.in | 8 ++++++++
 src/app/qgsgeometryvalidationservice.cpp      | 5 ++++-
 src/core/qgsmaplayer.cpp                      | 1 +
 src/core/qgsmaplayer.h                        | 8 ++++++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/python/core/auto_generated/qgsmaplayer.sip.in b/python/core/auto_generated/qgsmaplayer.sip.in
index dcf8d75ea35..7dabfa8ede7 100644
--- a/python/core/auto_generated/qgsmaplayer.sip.in
+++ b/python/core/auto_generated/qgsmaplayer.sip.in
@@ -1398,6 +1398,14 @@ Sets the coordinate transform context to ``transformContext``
 
   signals:
 
+    void beforeResolveReferences( QgsProject *project );
+%Docstring
+Emitted when all layers are loaded and references can be resolved,
+just before the references of this layer are resolved.
+
+.. versionadded:: 3.10
+%End
+
     void statusChanged( const QString &status );
 %Docstring
 Emit a signal with status (e.g. to be caught by QgisApp and display a msg on status bar)
diff --git a/src/app/qgsgeometryvalidationservice.cpp b/src/app/qgsgeometryvalidationservice.cpp
index 6d69f4fa2b4..f9dff0aa0ee 100644
--- a/src/app/qgsgeometryvalidationservice.cpp
+++ b/src/app/qgsgeometryvalidationservice.cpp
@@ -99,7 +99,10 @@ void QgsGeometryValidationService::onLayersAdded( const QList<QgsMapLayer *> &la
         mLayerChecks.remove( vectorLayer );
       } );
 
-      enableLayerChecks( vectorLayer );
+      connect( vectorLayer, &QgsMapLayer::beforeResolveReferences, this, [this, vectorLayer]()
+      {
+        enableLayerChecks( vectorLayer );
+      } );
     }
   }
 }
diff --git a/src/core/qgsmaplayer.cpp b/src/core/qgsmaplayer.cpp
index c5b79b914b9..a210e1efae7 100644
--- a/src/core/qgsmaplayer.cpp
+++ b/src/core/qgsmaplayer.cpp
@@ -612,6 +612,7 @@ QString QgsMapLayer::decodedSource( const QString &source, const QString &dataPr
 
 void QgsMapLayer::resolveReferences( QgsProject *project )
 {
+  emit beforeResolveReferences( project );
   if ( m3DRenderer )
     m3DRenderer->resolveReferences( *project );
 }
diff --git a/src/core/qgsmaplayer.h b/src/core/qgsmaplayer.h
index 31adb317784..70e368da208 100644
--- a/src/core/qgsmaplayer.h
+++ b/src/core/qgsmaplayer.h
@@ -1254,6 +1254,14 @@ class CORE_EXPORT QgsMapLayer : public QObject
 
   signals:
 
+    /**
+     * Emitted when all layers are loaded and references can be resolved,
+     * just before the references of this layer are resolved.
+     *
+     * \since QGIS 3.10
+     */
+    void beforeResolveReferences( QgsProject *project );
+
     //! Emit a signal with status (e.g. to be caught by QgisApp and display a msg on status bar)
     void statusChanged( const QString &status );