Allow data item providers to override default directory handling

python/core/qgsdataitemprovider.sip

@@ -10,6 +10,8 @@
 
 
 
+
+
 class QgsDataItemProvider
 {
 %Docstring
@@ -54,6 +56,20 @@ Caller takes responsibility of deleting created items.
 Caller takes responsibility of deleting created items.
  :rtype: list of QgsDataItem
 %End
+
+    virtual bool handlesDirectoryPath( const QString &path );
+%Docstring
+ Returns true if the provider will handle the directory at the specified ``path``.
+
+ If the provider indicates that it will handle the directory, the default creation and
+ population of directory items for the path will be avoided and it is left to the
+ provider to correctly populate relevant entries for the path.
+
+ The default implementation returns false for all paths.
+
+.. versionadded:: 3.0
+ :rtype: bool
+%End
 };
 
 /************************************************************************

src/core/qgsdataitem.cpp

@@ -703,6 +703,8 @@ QVector<QgsDataItem *> QgsDirectoryItem::createChildren()
   QVector<QgsDataItem *> children;
   QDir dir( mDirPath );
 
+  const QList<QgsDataItemProvider *> providers = QgsApplication::dataItemProviderRegistry()->providers();
+
   QStringList entries = dir.entryList( QDir::AllDirs | QDir::NoDotAndDotDot, QDir::Name | QDir::IgnoreCase );
   Q_FOREACH ( const QString &subdir, entries )
   {
@@ -719,6 +721,19 @@ QVector<QgsDataItem *> QgsDirectoryItem::createChildren()
     QString path = mPath + '/' + subdir; // may differ from subdirPath
     if ( QgsDirectoryItem::hiddenPath( path ) )
       continue;
+
+    bool handledByProvider = false;
+    for ( QgsDataItemProvider *provider : providers )
+    {
+      if ( provider->handlesDirectoryPath( path ) )
+      {
+        handledByProvider = true;
+        break;
+      }
+    }
+    if ( handledByProvider )
+      continue;
+
     QgsDirectoryItem *item = new QgsDirectoryItem( this, subdir, subdirPath, path );
     // propagate signals up to top
 
@@ -755,7 +770,7 @@ QVector<QgsDataItem *> QgsDirectoryItem::createChildren()
       }
     }
 
-    Q_FOREACH ( QgsDataItemProvider *provider, QgsApplication::dataItemProviderRegistry()->providers() )
+    for ( QgsDataItemProvider *provider : providers )
     {
       int capabilities = provider->capabilities();
 

src/core/qgsdataitemprovider.cpp

@@ -16,3 +16,8 @@
 #include "qgsdataitemprovider.h"
 
 // no implementation currently
+
+bool QgsDataItemProvider::handlesDirectoryPath( const QString & )
+{
+  return false;
+}

src/core/qgsdataitemprovider.h

@@ -24,6 +24,10 @@ class QgsDataItem;
 
 class QString;
 
+//! handlesDirectoryPath function
+typedef bool handlesDirectoryPath_t( const QString &path ) SIP_SKIP;
+
+
 /** \ingroup core
  * This is the interface for those who want to add custom data items to the browser tree.
  *
@@ -54,6 +58,19 @@ class CORE_EXPORT QgsDataItemProvider
     //! Create a vector of instances of QgsDataItem (or null) for given path and parent item.
     //! Caller takes responsibility of deleting created items.
     virtual QVector<QgsDataItem *> createDataItems( const QString &path, QgsDataItem *parentItem ) { Q_UNUSED( path ); Q_UNUSED( parentItem ); return QVector<QgsDataItem *>(); }
+
+    /**
+     * Returns true if the provider will handle the directory at the specified \a path.
+     *
+     * If the provider indicates that it will handle the directory, the default creation and
+     * population of directory items for the path will be avoided and it is left to the
+     * provider to correctly populate relevant entries for the path.
+     *
+     * The default implementation returns false for all paths.
+     *
+     * \since QGIS 3.0
+     */
+    virtual bool handlesDirectoryPath( const QString &path );
 };
 
 #endif // QGSDATAITEMPROVIDER_H

src/core/qgsdataitemproviderregistry.cpp

@@ -36,10 +36,11 @@ typedef QList<QgsDataItemProvider *> *dataItemProviders_t();
 class QgsDataItemProviderFromPlugin : public QgsDataItemProvider
 {
   public:
-    QgsDataItemProviderFromPlugin( const QString &name, dataCapabilities_t *capabilitiesFunc, dataItem_t *dataItemFunc )
+    QgsDataItemProviderFromPlugin( const QString &name, dataCapabilities_t *capabilitiesFunc, dataItem_t *dataItemFunc, handlesDirectoryPath_t *handlesDirectoryPathFunc )
       : mName( name )
       , mCapabilitiesFunc( capabilitiesFunc )
       , mDataItemFunc( dataItemFunc )
+      , mHandlesDirectoryPathFunc( handlesDirectoryPathFunc )
     {
     }
 
@@ -49,10 +50,19 @@ class QgsDataItemProviderFromPlugin : public QgsDataItemProvider
 
     QgsDataItem *createDataItem( const QString &path, QgsDataItem *parentItem ) override { return mDataItemFunc( path, parentItem ); }
 
+    bool handlesDirectoryPath( const QString &path ) override
+    {
+      if ( mHandlesDirectoryPathFunc )
+        return mHandlesDirectoryPathFunc( path );
+      else
+        return false;
+    }
+
   protected:
     QString mName;
     dataCapabilities_t *mCapabilitiesFunc = nullptr;
     dataItem_t *mDataItemFunc = nullptr;
+    handlesDirectoryPath_t *mHandlesDirectoryPathFunc = nullptr;
 };
 
 
@@ -93,7 +103,9 @@ QgsDataItemProviderRegistry::QgsDataItemProviderRegistry()
       continue;
     }
 
-    mProviders.append( new QgsDataItemProviderFromPlugin( library->fileName(), dataCapabilities, dataItem ) );
+    handlesDirectoryPath_t *handlesDirectoryPath = reinterpret_cast< handlesDirectoryPath_t * >( cast_to_fptr( library->resolve( "handlesDirectoryPath" ) ) );
+
+    mProviders.append( new QgsDataItemProviderFromPlugin( library->fileName(), dataCapabilities, dataItem, handlesDirectoryPath ) );
   }
 }
 

src/providers/ogr/qgsogrdataitems.cpp

@@ -668,3 +668,12 @@ QGISEXTERN QgsDataItem *dataItem( QString path, QgsDataItem *parentItem )
   OGR_DS_Destroy( hDataSource );
   return item;
 }
+
+QGISEXTERN bool handlesDirectoryPath( const QString &path )
+{
+  QFileInfo info( path );
+  QString suffix = info.suffix().toLower();
+
+  QStringList dirExtensions = directoryExtensions();
+  return dirExtensions.contains( suffix );
+}