fix null temporal properties

python/core/auto_generated/mesh/qgsmeshlayertemporalproperties.sip.in

@@ -89,6 +89,22 @@ Returns the method used to match dataset from temporal capabilities
 Sets the method used to match dataset from temporal capabilities
 
 :param matchingMethod: the matching method
+%End
+
+    bool isValid() const;
+%Docstring
+Returns whether the instance is valid
+
+.. versionadded:: 3.22
+%End
+
+    void setIsValid( bool isValid );
+%Docstring
+Sets whether the instance is valid
+
+:param isValid: whether the instance is valid
+
+.. versionadded:: 3.22
 %End
 
 };

python/core/auto_generated/mesh/qgsmeshrenderersettings.sip.in

@@ -747,6 +747,13 @@ Returns the active vector dataset group
 Sets the active vector dataset group
 
 .. versionadded:: 3.14
+%End
+
+    bool hasSettings( int datasetGroupIndex ) const;
+%Docstring
+Returns whether the group with ``index`` has render settings (scalar or vector)
+
+.. versionadded:: 3.22
 %End
 
 };

src/core/mesh/qgsmeshlayer.cpp

@@ -49,8 +49,8 @@ QgsMeshLayer::QgsMeshLayer( const QString &meshLayerPath,
                             const QString &providerKey,
                             const QgsMeshLayer::LayerOptions &options )
   : QgsMapLayer( QgsMapLayerType::MeshLayer, baseName, meshLayerPath ),
-    mDatasetGroupStore( new QgsMeshDatasetGroupStore( this ) )
-
+    mDatasetGroupStore( new QgsMeshDatasetGroupStore( this ) ),
+    mTemporalProperties( new QgsMeshLayerTemporalProperties( this ) )
 {
   mShouldValidateCrs = !options.skipCrsValidation;
 
@@ -1159,7 +1159,6 @@ void QgsMeshLayer::setDataSourcePrivate( const QString &dataSource, const QStrin
 
   if ( !mDataSource.isEmpty() && !provider.isEmpty() )
     setDataProvider( provider, options, flags );
-
 }
 
 QgsPointXY QgsMeshLayer::snapOnElement( QgsMesh::ElementType elementType, const QgsPointXY &point, double searchRadius )
@@ -1497,8 +1496,6 @@ bool QgsMeshLayer::readXml( const QDomNode &layer_node, QgsReadWriteContext &con
   else
     mDatasetGroupStore->readXml( elemDatasetGroupsStore, context );
 
-  mTemporalProperties = new QgsMeshLayerTemporalProperties( this );
-
   setDataProvider( mProviderKey, providerOptions, flags );
 
   QString errorMsg;
@@ -1706,9 +1703,8 @@ bool QgsMeshLayer::setDataProvider( QString const &provider, const QgsDataProvid
     return false;
   }
 
-  if ( !mTemporalProperties )
+  if ( !mTemporalProperties->isValid() )
   {
-    mTemporalProperties = new QgsMeshLayerTemporalProperties( this );
     mTemporalProperties->setDefaultsFromDataProviderTemporalCapabilities( dataProvider()->temporalCapabilities() );
   }
 

src/core/mesh/qgsmeshlayertemporalproperties.cpp

@@ -61,6 +61,7 @@ bool QgsMeshLayerTemporalProperties::readXml( const QDomElement &element, const
   mMatchingMethod = static_cast<QgsMeshDataProviderTemporalCapabilities::MatchingTemporalDatasetMethod>(
                       temporalElement.attribute( QStringLiteral( "matching-method" ) ).toInt() );
 
+  mIsValid = true;
   return true;
 }
 
@@ -74,6 +75,8 @@ void QgsMeshLayerTemporalProperties::setDefaultsFromDataProviderTemporalCapabili
 
   if ( mReferenceTime.isValid() )
     mTimeExtent = temporalCapabilities->timeExtent();
+
+  mIsValid = true;
 }
 
 QgsDateTimeRange QgsMeshLayerTemporalProperties::calculateTemporalExtent( QgsMapLayer * ) const
@@ -112,3 +115,13 @@ void QgsMeshLayerTemporalProperties::setMatchingMethod( const QgsMeshDataProvide
 {
   mMatchingMethod = matchingMethod;
 }
+
+bool QgsMeshLayerTemporalProperties::isValid() const
+{
+  return mIsValid;
+}
+
+void QgsMeshLayerTemporalProperties::setIsValid( bool isValid )
+{
+  mIsValid = isValid;
+}

src/core/mesh/qgsmeshlayertemporalproperties.h

@@ -100,11 +100,28 @@ class CORE_EXPORT QgsMeshLayerTemporalProperties : public QgsMapLayerTemporalPro
      */
     void setMatchingMethod( const QgsMeshDataProviderTemporalCapabilities::MatchingTemporalDatasetMethod &matchingMethod );
 
+    /**
+     * Returns whether the instance is valid
+     *
+     * \since QGIS 3.22
+     */
+    bool isValid() const;
+
+    /**
+     * Sets whether the instance is valid
+     *
+     * \param isValid whether the instance is valid
+     *
+     * \since QGIS 3.22
+     */
+    void setIsValid( bool isValid );
+
   private:
     QDateTime mReferenceTime;
     QgsDateTimeRange mTimeExtent;
     QgsMeshDataProviderTemporalCapabilities::MatchingTemporalDatasetMethod mMatchingMethod =
       QgsMeshDataProviderTemporalCapabilities::FindClosestDatasetBeforeStartRangeTime;
+    bool mIsValid = false;
 };
 
 #endif // QGSMESHLAYERTEMPORALPROPERTIES_H