[bugfix] Pass QgsReadWriteContext into project XML r/w

Or we miss the path resolver and we do not read/write
relative paths correctly

Fixes #17116

python/core/composer/qgscomposeritemgroup.sip

@@ -8,6 +8,7 @@
 
 
 
+
 class QgsComposerItemGroup: QgsComposerItem
 {
 %Docstring

python/core/composer/qgscomposerobject.sip

@@ -9,6 +9,7 @@
 
 
 
+
 class QgsComposerObject: QObject, QgsExpressionContextGenerator
 {
 %Docstring

python/core/layertree/qgslayertree.sip

@@ -122,7 +122,7 @@ class QgsLayerTree : QgsLayerTreeGroup
 .. versionadded:: 3.0
 %End
 
-    static QgsLayerTree *readXml( QDomElement &element );
+    static QgsLayerTree *readXml( QDomElement &element, const QgsReadWriteContext &context );
 %Docstring
  Load the layer tree from an XML element.
  It is not required that layers are loaded at this point.
@@ -141,7 +141,7 @@ class QgsLayerTree : QgsLayerTreeGroup
 .. versionadded:: 3.0
 %End
 
-    virtual void writeXml( QDomElement &parentElement );
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context );
 
     virtual QgsLayerTree *clone() const /Factory/;
 

python/core/layertree/qgslayertreegroup.sip

@@ -138,14 +138,14 @@ class QgsLayerTreeGroup : QgsLayerTreeNode
  :rtype: QgsLayerTreeGroup
 %End
 
-    static QgsLayerTreeGroup *readXml( QDomElement &element ) /Factory/;
+    static QgsLayerTreeGroup *readXml( QDomElement &element, const QgsReadWriteContext &context ) /Factory/;
 %Docstring
  Read group (tree) from XML element <layer-tree-group> and return the newly created group (or null on error).
  Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
  :rtype: QgsLayerTreeGroup
 %End
 
-    static QgsLayerTreeGroup *readXml( QDomElement &element, const QgsProject *project ) /Factory/;
+    static QgsLayerTreeGroup *readXml( QDomElement &element, const QgsProject *project, const QgsReadWriteContext &context ) /Factory/;
 %Docstring
  Read group (tree) from XML element <layer-tree-group> and return the newly created group (or null on error).
  Also resolves textual references to layers from the project (calls resolveReferences() internally).
@@ -153,12 +153,12 @@ class QgsLayerTreeGroup : QgsLayerTreeNode
  :rtype: QgsLayerTreeGroup
 %End
 
-    virtual void writeXml( QDomElement &parentElement );
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context );
 %Docstring
  Write group (tree) as XML element <layer-tree-group> and add it to the given parent element
 %End
 
-    void readChildrenFromXml( QDomElement &element );
+    void readChildrenFromXml( QDomElement &element, const QgsReadWriteContext &context );
 %Docstring
  Read children from XML and append them to the group.
  Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.

python/core/layertree/qgslayertreelayer.sip

@@ -63,14 +63,14 @@ class QgsLayerTreeLayer : QgsLayerTreeNode
 .. versionadded:: 3.0
 %End
 
-    static QgsLayerTreeLayer *readXml( QDomElement &element ) /Factory/;
+    static QgsLayerTreeLayer *readXml( QDomElement &element, const QgsReadWriteContext &context ) /Factory/;
 %Docstring
  Read layer node from XML. Returns new instance.
  Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
  :rtype: QgsLayerTreeLayer
 %End
 
-    static QgsLayerTreeLayer *readXml( QDomElement &element, const QgsProject *project ) /Factory/;
+    static QgsLayerTreeLayer *readXml( QDomElement &element, const QgsProject *project, const QgsReadWriteContext &context ) /Factory/;
 %Docstring
  Read layer node from XML. Returns new instance.
  Also resolves textual references to layers from the project (calls resolveReferences() internally).
@@ -78,7 +78,7 @@ class QgsLayerTreeLayer : QgsLayerTreeNode
  :rtype: QgsLayerTreeLayer
 %End
 
-    virtual void writeXml( QDomElement &parentElement );
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context );
 
     virtual QString dump() const;
 

python/core/layertree/qgslayertreenode.sip

@@ -111,7 +111,7 @@ Get list of children of the node. Children are owned by the parent
 .. versionadded:: 3.0
 %End
 
-    static QgsLayerTreeNode *readXml( QDomElement &element ) /Factory/;
+    static QgsLayerTreeNode *readXml( QDomElement &element, const QgsReadWriteContext &context ) /Factory/;
 %Docstring
  Read layer tree from XML. Returns new instance.
  Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
@@ -126,7 +126,7 @@ Get list of children of the node. Children are owned by the parent
  :rtype: QgsLayerTreeNode
 %End
 
-    virtual void writeXml( QDomElement &parentElement ) = 0;
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context ) = 0;
 %Docstring
 Write layer tree to XML
 %End

src/app/qgsprojectlayergroupdialog.cpp

@@ -170,7 +170,7 @@ void QgsProjectLayerGroupDialog::changeProjectFile()
   QDomElement layerTreeElem = projectDom.documentElement().firstChildElement( QStringLiteral( "layer-tree-group" ) );
   if ( !layerTreeElem.isNull() )
   {
-    mRootGroup->readChildrenFromXml( layerTreeElem );
+    mRootGroup->readChildrenFromXml( layerTreeElem, QgsReadWriteContext() );
   }
   else
   {

src/core/composer/qgscomposerarrow.cpp

@@ -429,7 +429,6 @@ bool QgsComposerArrow::writeXml( QDomElement &elem, QDomDocument &doc ) const
 
   QgsReadWriteContext context;
   context.setPathResolver( pathResolver );
-
   // absolute paths to relative
   QString startMarkerPath = QgsSymbolLayerUtils::svgSymbolPathToName( mStartMarkerFile, pathResolver );
   QString endMarkerPath = QgsSymbolLayerUtils::svgSymbolPathToName( mEndMarkerFile, pathResolver );

src/core/composer/qgscomposeritem.cpp

@@ -143,6 +143,12 @@ void QgsComposerItem::setSelected( bool s )
 
 bool QgsComposerItem::_writeXml( QDomElement &itemElem, QDomDocument &doc ) const
 {
+  QgsPathResolver pathResolver;
+  if ( composition() )
+    pathResolver = composition()->project()->pathResolver();
+  QgsReadWriteContext context;
+  context.setPathResolver( pathResolver );
+
   if ( itemElem.isNull() )
   {
     return false;

src/core/composer/qgscomposeritemgroup.h

@@ -20,6 +20,8 @@
 #include "qgis_core.h"
 #include "qgis.h"
 #include "qgscomposeritem.h"
+#include "qgsreadwritecontext.h"
+
 #include <QSet>
 
 /**

src/core/composer/qgscomposerlegend.cpp

@@ -344,6 +344,12 @@ bool QgsComposerLegend::writeXml( QDomElement &elem, QDomDocument &doc ) const
     return false;
   }
 
+  QgsPathResolver  pathResolver;
+  if ( mComposition )
+    pathResolver = mComposition->project()->pathResolver();
+  QgsReadWriteContext context;
+  context.setPathResolver( pathResolver );
+
   QDomElement composerLegendElem = doc.createElement( QStringLiteral( "ComposerLegend" ) );
   elem.appendChild( composerLegendElem );
 
@@ -389,7 +395,7 @@ bool QgsComposerLegend::writeXml( QDomElement &elem, QDomDocument &doc ) const
   if ( mCustomLayerTree )
   {
     // if not using auto-update - store the custom layer tree
-    mCustomLayerTree->writeXml( composerLegendElem );
+    mCustomLayerTree->writeXml( composerLegendElem, context );
   }
 
   if ( mLegendFilterByMap )
@@ -408,6 +414,12 @@ bool QgsComposerLegend::readXml( const QDomElement &itemElem, const QDomDocument
     return false;
   }
 
+  QgsPathResolver  pathResolver;
+  if ( mComposition )
+    pathResolver = mComposition->project()->pathResolver();
+  QgsReadWriteContext context;
+  context.setPathResolver( pathResolver );
+
   //read general properties
   mTitle = itemElem.attribute( QStringLiteral( "title" ) );
   mSettings.setTitle( mTitle );
@@ -479,7 +491,7 @@ bool QgsComposerLegend::readXml( const QDomElement &itemElem, const QDomDocument
 
   if ( !layerTreeElem.isNull() )
   {
-    std::unique_ptr< QgsLayerTree > tree( QgsLayerTree::readXml( layerTreeElem ) );
+    std::unique_ptr< QgsLayerTree > tree( QgsLayerTree::readXml( layerTreeElem, context ) );
     if ( mComposition )
       tree->resolveReferences( mComposition->project(), true );
     setCustomLayerTree( tree.release() );

src/core/composer/qgscomposernodesitem.cpp

@@ -272,6 +272,7 @@ bool QgsComposerNodesItem::moveNode( const int index, QPointF pt )
 bool QgsComposerNodesItem::readXml( const QDomElement &itemElem,
                                     const QDomDocument &doc )
 {
+
   // restore general composer item properties
   const QDomNodeList composerItemList = itemElem.elementsByTagName( QStringLiteral( "ComposerItem" ) );
   if ( !composerItemList.isEmpty() )

src/core/composer/qgscomposerobject.h

@@ -22,6 +22,8 @@
 #include "qgsobjectcustomproperties.h"
 #include "qgsexpressioncontextgenerator.h"
 #include "qgspropertycollection.h"
+#include "qgsreadwritecontext.h"
+
 #include <QObject>
 #include <QDomNode>
 #include <QMap>

src/core/layertree/qgslayertree.cpp

@@ -99,18 +99,18 @@ void QgsLayerTree::setHasCustomLayerOrder( bool hasCustomLayerOrder )
   emit layerOrderChanged();
 }
 
-QgsLayerTree *QgsLayerTree::readXml( QDomElement &element )
+QgsLayerTree *QgsLayerTree::readXml( QDomElement &element, const QgsReadWriteContext &context )
 {
   QgsLayerTree *tree = new QgsLayerTree();
 
   tree->readCommonXml( element );
 
-  tree->readChildrenFromXml( element );
+  tree->readChildrenFromXml( element, context );
 
   return tree;
 }
 
-void QgsLayerTree::writeXml( QDomElement &parentElement )
+void QgsLayerTree::writeXml( QDomElement &parentElement, const QgsReadWriteContext &context )
 {
   QDomDocument doc = parentElement.ownerDocument();
   QDomElement elem = doc.createElement( QStringLiteral( "layer-tree-group" ) );
@@ -118,7 +118,7 @@ void QgsLayerTree::writeXml( QDomElement &parentElement )
   writeCommonXml( elem );
 
   Q_FOREACH ( QgsLayerTreeNode *node, mChildren )
-    node->writeXml( elem );
+    node->writeXml( elem, context );
 
   QDomElement customOrderElem = doc.createElement( QStringLiteral( "custom-order" ) );
   customOrderElem.setAttribute( QStringLiteral( "enabled" ), mHasCustomLayerOrder ? 1 : 0 );

src/core/layertree/qgslayertree.h

@@ -172,7 +172,7 @@ class CORE_EXPORT QgsLayerTree : public QgsLayerTreeGroup
      *
      * \since QGIS 3.0
      */
-    static QgsLayerTree *readXml( QDomElement &element );
+    static QgsLayerTree *readXml( QDomElement &element, const QgsReadWriteContext &context );
 
     /**
      * Load the layer order from an XML element.
@@ -182,7 +182,7 @@ class CORE_EXPORT QgsLayerTree : public QgsLayerTreeGroup
      */
     void readLayerOrderFromXml( const QDomElement &doc );
 
-    virtual void writeXml( QDomElement &parentElement ) override;
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context ) override;
 
     virtual QgsLayerTree *clone() const override SIP_FACTORY;
 

src/core/layertree/qgslayertreegroup.cpp

@@ -249,7 +249,7 @@ QgsLayerTreeGroup *QgsLayerTreeGroup::findGroup( const QString &name )
   return nullptr;
 }
 
-QgsLayerTreeGroup *QgsLayerTreeGroup::readXml( QDomElement &element )
+QgsLayerTreeGroup *QgsLayerTreeGroup::readXml( QDomElement &element, const QgsReadWriteContext &context )
 {
   if ( element.tagName() != QLatin1String( "layer-tree-group" ) )
     return nullptr;
@@ -265,22 +265,22 @@ QgsLayerTreeGroup *QgsLayerTreeGroup::readXml( QDomElement &element )
 
   groupNode->readCommonXml( element );
 
-  groupNode->readChildrenFromXml( element );
+  groupNode->readChildrenFromXml( element, context );
 
   groupNode->setIsMutuallyExclusive( isMutuallyExclusive, mutuallyExclusiveChildIndex );
 
   return groupNode;
 }
 
-QgsLayerTreeGroup *QgsLayerTreeGroup::readXml( QDomElement &element, const QgsProject *project )
+QgsLayerTreeGroup *QgsLayerTreeGroup::readXml( QDomElement &element, const QgsProject *project, const QgsReadWriteContext &context )
 {
-  QgsLayerTreeGroup *node = readXml( element );
+  QgsLayerTreeGroup *node = readXml( element, context );
   if ( node )
     node->resolveReferences( project );
   return node;
 }
 
-void QgsLayerTreeGroup::writeXml( QDomElement &parentElement )
+void QgsLayerTreeGroup::writeXml( QDomElement &parentElement, const QgsReadWriteContext &context )
 {
   QDomDocument doc = parentElement.ownerDocument();
   QDomElement elem = doc.createElement( QStringLiteral( "layer-tree-group" ) );
@@ -296,18 +296,18 @@ void QgsLayerTreeGroup::writeXml( QDomElement &parentElement )
   writeCommonXml( elem );
 
   Q_FOREACH ( QgsLayerTreeNode *node, mChildren )
-    node->writeXml( elem );
+    node->writeXml( elem, context );
 
   parentElement.appendChild( elem );
 }
 
-void QgsLayerTreeGroup::readChildrenFromXml( QDomElement &element )
+void QgsLayerTreeGroup::readChildrenFromXml( QDomElement &element, const QgsReadWriteContext &context )
 {
   QList<QgsLayerTreeNode *> nodes;
   QDomElement childElem = element.firstChildElement();
   while ( !childElem.isNull() )
   {
-    QgsLayerTreeNode *newNode = QgsLayerTreeNode::readXml( childElem );
+    QgsLayerTreeNode *newNode = QgsLayerTreeNode::readXml( childElem, context );
     if ( newNode )
       nodes << newNode;
 

src/core/layertree/qgslayertreegroup.h

@@ -145,25 +145,25 @@ class CORE_EXPORT QgsLayerTreeGroup : public QgsLayerTreeNode
      * Read group (tree) from XML element <layer-tree-group> and return the newly created group (or null on error).
      * Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
      */
-    static QgsLayerTreeGroup *readXml( QDomElement &element ) SIP_FACTORY;
+    static QgsLayerTreeGroup *readXml( QDomElement &element, const QgsReadWriteContext &context ) SIP_FACTORY;
 
     /**
      * Read group (tree) from XML element <layer-tree-group> and return the newly created group (or null on error).
      * Also resolves textual references to layers from the project (calls resolveReferences() internally).
      * \since QGIS 3.0
      */
-    static QgsLayerTreeGroup *readXml( QDomElement &element, const QgsProject *project ) SIP_FACTORY;
+    static QgsLayerTreeGroup *readXml( QDomElement &element, const QgsProject *project, const QgsReadWriteContext &context ) SIP_FACTORY;
 
     /**
      * Write group (tree) as XML element <layer-tree-group> and add it to the given parent element
      */
-    virtual void writeXml( QDomElement &parentElement ) override;
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context ) override;
 
     /**
      * Read children from XML and append them to the group.
      * Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
      */
-    void readChildrenFromXml( QDomElement &element );
+    void readChildrenFromXml( QDomElement &element, const QgsReadWriteContext &context );
 
     /**
      * Return text representation of the tree. For debugging purposes only.

src/core/layertree/qgslayertreelayer.cpp

@@ -97,8 +97,9 @@ void QgsLayerTreeLayer::setName( const QString &n )
   }
 }
 
-QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element )
+QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element, const QgsReadWriteContext &context )
 {
+  Q_UNUSED( context );
   if ( element.tagName() != QLatin1String( "layer-tree-layer" ) )
     return nullptr;
 
@@ -106,7 +107,7 @@ QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element )
   QString layerName = element.attribute( QStringLiteral( "name" ) );
 
   QString providerKey = element.attribute( QStringLiteral( "providerKey" ) );
-  QString source = element.attribute( QStringLiteral( "source" ) );
+  QString source = context.pathResolver().readPath( element.attribute( QStringLiteral( "source" ) ) );
 
   Qt::CheckState checked = QgsLayerTreeUtils::checkStateFromXml( element.attribute( QStringLiteral( "checked" ) ) );
   bool isExpanded = ( element.attribute( QStringLiteral( "expanded" ), QStringLiteral( "1" ) ) == QLatin1String( "1" ) );
@@ -121,15 +122,15 @@ QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element )
   return nodeLayer;
 }
 
-QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element, const QgsProject *project )
+QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element, const QgsProject *project, const QgsReadWriteContext &context )
 {
-  QgsLayerTreeLayer *node = readXml( element );
+  QgsLayerTreeLayer *node = readXml( element, context );
   if ( node )
     node->resolveReferences( project );
   return node;
 }
 
-void QgsLayerTreeLayer::writeXml( QDomElement &parentElement )
+void QgsLayerTreeLayer::writeXml( QDomElement &parentElement, const QgsReadWriteContext &context )
 {
   QDomDocument doc = parentElement.ownerDocument();
   QDomElement elem = doc.createElement( QStringLiteral( "layer-tree-layer" ) );
@@ -138,7 +139,7 @@ void QgsLayerTreeLayer::writeXml( QDomElement &parentElement )
 
   if ( mRef )
   {
-    elem.setAttribute( QStringLiteral( "source" ), mRef->publicSource() );
+    elem.setAttribute( QStringLiteral( "source" ), context.pathResolver().writePath( mRef->publicSource() ) );
     elem.setAttribute( QStringLiteral( "providerKey" ), mRef->dataProvider() ? mRef->dataProvider()->name() : QString() );
   }
 

src/core/layertree/qgslayertreelayer.h

@@ -20,6 +20,7 @@
 #include "qgis.h"
 #include "qgslayertreenode.h"
 #include "qgsmaplayerref.h"
+#include "qgsreadwritecontext.h"
 
 class QgsMapLayer;
 
@@ -73,16 +74,16 @@ class CORE_EXPORT QgsLayerTreeLayer : public QgsLayerTreeNode
      * Read layer node from XML. Returns new instance.
      * Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
      */
-    static QgsLayerTreeLayer *readXml( QDomElement &element ) SIP_FACTORY;
+    static QgsLayerTreeLayer *readXml( QDomElement &element, const QgsReadWriteContext &context ) SIP_FACTORY;
 
     /**
      * Read layer node from XML. Returns new instance.
      * Also resolves textual references to layers from the project (calls resolveReferences() internally).
      * \since QGIS 3.0
      */
-    static QgsLayerTreeLayer *readXml( QDomElement &element, const QgsProject *project ) SIP_FACTORY;
+    static QgsLayerTreeLayer *readXml( QDomElement &element, const QgsProject *project, const QgsReadWriteContext &context ) SIP_FACTORY;
 
-    virtual void writeXml( QDomElement &parentElement ) override;
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context ) override;
 
     virtual QString dump() const override;
 

src/core/layertree/qgslayertreemodel.cpp

@@ -999,7 +999,7 @@ QMimeData *QgsLayerTreeModel::mimeData( const QModelIndexList &indexes ) const
   QDomDocument doc;
   QDomElement rootElem = doc.createElement( QStringLiteral( "layer_tree_model_data" ) );
   Q_FOREACH ( QgsLayerTreeNode *node, nodesFinal )
-    node->writeXml( rootElem );
+    node->writeXml( rootElem, QgsReadWriteContext() );
   doc.appendChild( rootElem );
   QString txt = doc.toString();
 

src/core/layertree/qgslayertreenode.cpp

@@ -47,20 +47,26 @@ QgsLayerTreeNode::~QgsLayerTreeNode()
   qDeleteAll( mChildren );
 }
 
-QgsLayerTreeNode *QgsLayerTreeNode::readXml( QDomElement &element )
+QgsLayerTreeNode *QgsLayerTreeNode::readXml( QDomElement &element, const QgsReadWriteContext &context )
 {
   QgsLayerTreeNode *node = nullptr;
   if ( element.tagName() == QLatin1String( "layer-tree-group" ) )
-    node = QgsLayerTreeGroup::readXml( element );
+    node = QgsLayerTreeGroup::readXml( element, context );
   else if ( element.tagName() == QLatin1String( "layer-tree-layer" ) )
-    node = QgsLayerTreeLayer::readXml( element );
+    node = QgsLayerTreeLayer::readXml( element, context );
 
   return node;
 }
 
 QgsLayerTreeNode *QgsLayerTreeNode::readXml( QDomElement &element, const QgsProject *project )
 {
-  QgsLayerTreeNode *node = readXml( element );
+  QgsReadWriteContext context;
+  QgsPathResolver resolver;
+  if ( project )
+    resolver = project->pathResolver();
+  context.setPathResolver( resolver );
+
+  QgsLayerTreeNode *node = readXml( element, context );
   if ( node )
     node->resolveReferences( project );
   return node;

src/core/layertree/qgslayertreenode.h

@@ -20,6 +20,7 @@
 #include <QObject>
 
 #include "qgsobjectcustomproperties.h"
+#include "qgsreadwritecontext.h"
 #include "qgis.h"
 
 class QDomElement;
@@ -126,7 +127,7 @@ class CORE_EXPORT QgsLayerTreeNode : public QObject
      * Read layer tree from XML. Returns new instance.
      * Does not resolve textual references to layers. Call resolveReferences() afterwards to do it.
      */
-    static QgsLayerTreeNode *readXml( QDomElement &element ) SIP_FACTORY;
+    static QgsLayerTreeNode *readXml( QDomElement &element, const QgsReadWriteContext &context ) SIP_FACTORY;
 
     /**
      * Read layer tree from XML. Returns new instance.
@@ -136,7 +137,7 @@ class CORE_EXPORT QgsLayerTreeNode : public QObject
     static QgsLayerTreeNode *readXml( QDomElement &element, const QgsProject *project ) SIP_FACTORY;
 
     //! Write layer tree to XML
-    virtual void writeXml( QDomElement &parentElement ) = 0;
+    virtual void writeXml( QDomElement &parentElement, const QgsReadWriteContext &context ) = 0;
 
     //! Return string with layer tree structure. For debug purposes only
     virtual QString dump() const = 0;

src/core/layout/qgslayoutitemlegend.cpp

@@ -448,8 +448,9 @@ void QgsLayoutItemLegend::updateLegend()
   updateFilterByMap( false );
 }
 
-bool QgsLayoutItemLegend::writePropertiesToElement( QDomElement &composerLegendElem, QDomDocument &doc, const QgsReadWriteContext & ) const
+bool QgsLayoutItemLegend::writePropertiesToElement( QDomElement &composerLegendElem, QDomDocument &doc, const QgsReadWriteContext &context ) const
 {
+
   //write general properties
   composerLegendElem.setAttribute( QStringLiteral( "title" ), mTitle );
   composerLegendElem.setAttribute( QStringLiteral( "titleAlignment" ), QString::number( static_cast< int >( mSettings.titleAlignment() ) ) );
@@ -492,7 +493,7 @@ bool QgsLayoutItemLegend::writePropertiesToElement( QDomElement &composerLegendE
   if ( mCustomLayerTree )
   {
     // if not using auto-update - store the custom layer tree
-    mCustomLayerTree->writeXml( composerLegendElem );
+    mCustomLayerTree->writeXml( composerLegendElem, context );
   }
 
   if ( mLegendFilterByMap )
@@ -504,7 +505,7 @@ bool QgsLayoutItemLegend::writePropertiesToElement( QDomElement &composerLegendE
   return true;
 }
 
-bool QgsLayoutItemLegend::readPropertiesFromElement( const QDomElement &itemElem, const QDomDocument &doc, const QgsReadWriteContext & )
+bool QgsLayoutItemLegend::readPropertiesFromElement( const QDomElement &itemElem, const QDomDocument &doc, const QgsReadWriteContext &context )
 {
   //read general properties
   mTitle = itemElem.attribute( QStringLiteral( "title" ) );
@@ -586,7 +587,7 @@ bool QgsLayoutItemLegend::readPropertiesFromElement( const QDomElement &itemElem
 
   if ( !layerTreeElem.isNull() )
   {
-    std::unique_ptr< QgsLayerTree > tree( QgsLayerTree::readXml( layerTreeElem ) );
+    std::unique_ptr< QgsLayerTree > tree( QgsLayerTree::readXml( layerTreeElem, context ) );
     if ( mLayout )
       tree->resolveReferences( mLayout->project(), true );
     setCustomLayerTree( tree.release() );

src/core/qgslayerdefinition.cpp

@@ -141,7 +141,7 @@ bool QgsLayerDefinition::loadLayerDefinition( QDomDocument doc, QgsProject *proj
   bool loadInLegend = true;
   if ( !layerTreeElem.isNull() )
   {
-    root->readChildrenFromXml( layerTreeElem );
+    root->readChildrenFromXml( layerTreeElem, context );
     loadInLegend = false;
   }
 
@@ -208,7 +208,7 @@ bool QgsLayerDefinition::exportLayerDefinition( QDomDocument doc, const QList<Qg
     QgsLayerTreeNode *newnode = node->clone();
     root->addChildNode( newnode );
   }
-  root->writeXml( qgiselm );
+  root->writeXml( qgiselm, context );
 
   QDomElement layerselm = doc.createElement( QStringLiteral( "maplayers" ) );
   QList<QgsLayerTreeLayer *> layers = root->findLayers();

src/core/qgsproject.cpp

@@ -924,7 +924,7 @@ bool QgsProject::readProjectFile( const QString &filename )
   QDomElement layerTreeElem = doc->documentElement().firstChildElement( QStringLiteral( "layer-tree-group" ) );
   if ( !layerTreeElem.isNull() )
   {
-    mRootGroup->readChildrenFromXml( layerTreeElem );
+    mRootGroup->readChildrenFromXml( layerTreeElem, context );
   }
   else
   {
@@ -1040,6 +1040,7 @@ bool QgsProject::readProjectFile( const QString &filename )
 
 void QgsProject::loadEmbeddedNodes( QgsLayerTreeGroup *group )
 {
+
   Q_FOREACH ( QgsLayerTreeNode *child, group->children() )
   {
     if ( QgsLayerTree::isGroup( child ) )
@@ -1050,7 +1051,6 @@ void QgsProject::loadEmbeddedNodes( QgsLayerTreeGroup *group )
         // make sure to convert the path from relative to absolute
         QString projectPath = readPath( childGroup->customProperty( QStringLiteral( "embedded_project" ) ).toString() );
         childGroup->setCustomProperty( QStringLiteral( "embedded_project" ), projectPath );
-
         QgsLayerTreeGroup *newGroup = createEmbeddedGroup( childGroup->name(), projectPath, childGroup->customProperty( QStringLiteral( "embedded-invisible-layers" ) ).toStringList() );
         if ( newGroup )
         {
@@ -1344,7 +1344,8 @@ bool QgsProject::writeProjectFile( const QString &filename )
   QgsLayerTreeNode *clonedRoot = mRootGroup->clone();
   QgsLayerTreeUtils::replaceChildrenOfEmbeddedGroups( QgsLayerTree::toGroup( clonedRoot ) );
   QgsLayerTreeUtils::updateEmbeddedGroupsProjectPath( QgsLayerTree::toGroup( clonedRoot ), this ); // convert absolute paths to relative paths if required
-  clonedRoot->writeXml( qgisNode );
+
+  clonedRoot->writeXml( qgisNode, context );
   delete clonedRoot;
 
   mSnappingConfig.writeProject( *doc );
@@ -1860,6 +1861,9 @@ QgsLayerTreeGroup *QgsProject::createEmbeddedGroup( const QString &groupName, co
     return nullptr;
   }
 
+  QgsReadWriteContext context;
+  context.setPathResolver( pathResolver() );
+
   // store identify disabled layers of the embedded project
   QSet<QString> embeddedIdentifyDisabledLayers;
   QDomElement disabledLayersElem = projectDocument.documentElement().firstChildElement( QStringLiteral( "properties" ) ).firstChildElement( QStringLiteral( "Identify" ) ).firstChildElement( QStringLiteral( "disabledLayers" ) );
@@ -1877,7 +1881,7 @@ QgsLayerTreeGroup *QgsProject::createEmbeddedGroup( const QString &groupName, co
   QDomElement layerTreeElem = projectDocument.documentElement().firstChildElement( QStringLiteral( "layer-tree-group" ) );
   if ( !layerTreeElem.isNull() )
   {
-    root->readChildrenFromXml( layerTreeElem );
+    root->readChildrenFromXml( layerTreeElem, context );
   }
   else
   {