Add a generic method for adding style entities to a QgsStyle

python/core/auto_generated/symbology/qgsstyle.sip.in

@@ -98,6 +98,21 @@ Constructor for QgsStyle.
       LabelSettingsEntity,
     };
 
+    bool addEntity( const QString &name, const QgsStyleEntityInterface *entity, bool update = false );
+%Docstring
+Adds an ``entity`` to the style, with the specified ``name``. Ownership is not transferred.
+
+If ``update`` is ``True`` then the style database is updated automatically as a result.
+
+Returns ``True`` if the add operation was successful.
+
+.. note::
+
+   Adding an entity with the name of existing one replaces the existing one automatically.
+
+.. versionadded:: 3.10
+%End
+
     bool addSymbol( const QString &name, QgsSymbol *symbol /Transfer/, bool update = false );
 %Docstring
 Adds a symbol to style and takes symbol's ownership

src/core/symbology/qgsstyle.cpp

@@ -43,6 +43,34 @@ QgsStyle::~QgsStyle()
   clear();
 }
 
+bool QgsStyle::addEntity( const QString &name, const QgsStyleEntityInterface *entity, bool update )
+{
+  switch ( entity->type() )
+  {
+    case SymbolEntity:
+      if ( !static_cast< const QgsStyleSymbolEntity * >( entity )->symbol() )
+        return false;
+      return addSymbol( name, static_cast< const QgsStyleSymbolEntity * >( entity )->symbol()->clone(), update );
+
+    case ColorrampEntity:
+      if ( !static_cast< const QgsStyleColorRampEntity * >( entity )->ramp() )
+        return false;
+      return addColorRamp( name, static_cast< const QgsStyleColorRampEntity * >( entity )->ramp()->clone(), update );
+
+    case TextFormatEntity:
+      return addTextFormat( name, static_cast< const QgsStyleTextFormatEntity * >( entity )->format(), update );
+
+    case LabelSettingsEntity:
+      return addLabelSettings( name, static_cast< const QgsStyleLabelSettingsEntity * >( entity )->settings(), update );
+
+    case TagEntity:
+    case SmartgroupEntity:
+      break;
+
+  }
+  return false;
+}
+
 QgsStyle *QgsStyle::defaultStyle() // static
 {
   if ( !sDefaultStyle )

src/core/symbology/qgsstyle.h

@@ -32,6 +32,7 @@
 class QgsSymbol;
 class QgsSymbolLayer;
 class QgsColorRamp;
+class QgsStyleEntityInterface;
 
 class QDomDocument;
 class QDomElement;
@@ -183,6 +184,19 @@ class CORE_EXPORT QgsStyle : public QObject
       LabelSettingsEntity, //!< Label settings
     };
 
+    /**
+     * Adds an \a entity to the style, with the specified \a name. Ownership is not transferred.
+     *
+     * If \a update is TRUE then the style database is updated automatically as a result.
+     *
+     * Returns TRUE if the add operation was successful.
+     *
+     * \note Adding an entity with the name of existing one replaces the existing one automatically.
+     *
+     * \since QGIS 3.10
+     */
+    bool addEntity( const QString &name, const QgsStyleEntityInterface *entity, bool update = false );
+
     /**
      * Adds a symbol to style and takes symbol's ownership
      *