[FIX #7609] Fetch and cache data for sorting column in one query

qgis · Apr 18, 2013 · 66fadee · 66fadee
1 parent 046fbee
commit 66fadee
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Showing 4 changed files with 82 additions and 7 deletions.
diff --git a/src/gui/attributetable/qgsattributetablefiltermodel.cpp b/src/gui/attributetable/qgsattributetablefiltermodel.cpp
@@ -86,6 +86,12 @@ bool QgsAttributeTableFilterModel::lessThan( const QModelIndex &left, const QMod
   return false;
 }
 
+void QgsAttributeTableFilterModel::sort( int column, Qt::SortOrder order )
+{
+  masterModel()->prefetchColumnData( column );
+  QSortFilterProxyModel::sort( column, order );
+}
+
 void QgsAttributeTableFilterModel::setSelectedOnTop( bool selectedOnTop )
 {
   if ( mSelectedOnTop != selectedOnTop )

diff --git a/src/gui/attributetable/qgsattributetablefiltermodel.h b/src/gui/attributetable/qgsattributetablefiltermodel.h
@@ -142,6 +142,15 @@ class GUI_EXPORT QgsAttributeTableFilterModel: public QSortFilterProxyModel, pub
      */
     bool lessThan( const QModelIndex &left, const QModelIndex &right ) const;
 
+    /**
+     * Sort by the given column using the given order.
+     * Prefetches all the data from the layer to speed up sorting.
+     *
+     * @param column The column which should be sorted
+     * @param order  The order ( Qt::AscendingOrder or Qt::DescendingOrder )
+     */
+    virtual void sort( int column, Qt::SortOrder order = Qt::AscendingOrder );
+
   public slots:
     /**
      * Is called upon every change of the visible extents on the map canvas.

diff --git a/src/gui/attributetable/qgsattributetablemodel.cpp b/src/gui/attributetable/qgsattributetablemodel.cpp
@@ -33,6 +33,7 @@
 QgsAttributeTableModel::QgsAttributeTableModel( QgsVectorLayerCache *layerCache, QObject *parent )
     : QAbstractTableModel( parent )
     , mLayerCache( layerCache )
+    , mCachedField( -1 )
 {
   QgsDebugMsg( "entered." );
 
@@ -80,7 +81,7 @@ bool QgsAttributeTableModel::loadFeatureAtId( QgsFeatureId fid ) const
 
 void QgsAttributeTableModel::featureDeleted( QgsFeatureId fid )
 {
-  QgsDebugMsgLevel( QString( "deleted fid=%1 => row=%2" ).arg( fid ).arg( idToRow( fid ) ), 3 );
+  prefetchColumnData( -1 ); // Invalidate cached column data
 
   int row = idToRow( fid );
 
@@ -131,8 +132,7 @@ bool QgsAttributeTableModel::removeRows( int row, int count, const QModelIndex &
 
 void QgsAttributeTableModel::featureAdded( QgsFeatureId fid, bool newOperation )
 {
-  QgsDebugMsgLevel( QString( "feature %1 added (%2, rows %3, ids %4)" ).arg( fid ).arg( newOperation ).arg( mRowIdMap.size() ).arg( mIdRowMap.size() ), 4 );
-
+  prefetchColumnData( -1 ); // Invalidate cached column data
   int n = mRowIdMap.size();
   if ( newOperation )
     beginInsertRows( QModelIndex(), n, n );
@@ -172,6 +172,9 @@ void QgsAttributeTableModel::layerDeleted()
 
 void QgsAttributeTableModel::attributeValueChanged( QgsFeatureId fid, int idx, const QVariant &value )
 {
+  if ( mCachedField == idx )
+    mFieldCache[ fid ] = value;
+
   if ( fid == mFeat.id() )
   {
     mFeat.setValid( false );
@@ -483,17 +486,30 @@ QVariant QgsAttributeTableModel::data( const QModelIndex &index, int role ) cons
       return QVariant( Qt::AlignLeft );
   }
 
+  const QVariant* pVal = NULL;
+
   // if we don't have the row in current cache, load it from layer first
   if ( mFeat.id() != rowId || !mFeat.isValid() )
   {
-    if ( !loadFeatureAtId( rowId ) )
+    if ( mCachedField == fieldId )
+    {
+      const QVariant& val = mFieldCache[rowId];
+      pVal = &val;
+    }
+    else if ( !loadFeatureAtId( rowId ) )
       return QVariant( "ERROR" );
   }
 
-  if ( mFeat.id() != rowId )
+  if ( pVal == NULL && mFeat.id() != rowId )
     return QVariant( "ERROR" );
 
-  const QVariant &val = mFeat.attribute( fieldId );
+  if ( !pVal )
+  {
+    const QVariant& val = mFeat.attribute( fieldId );
+    pVal =&val;
+  }
+
+  const QVariant& val = *pVal;
 
   // For sorting return unprocessed value
   if ( SortRole == role )
@@ -599,3 +615,30 @@ QgsFeature QgsAttributeTableModel::feature( const QModelIndex &idx ) const
 
   return f;
 }
+
+void QgsAttributeTableModel::prefetchColumnData( int column )
+{
+  mFieldCache.clear();
+
+  if ( column == -1 )
+  {
+    mCachedField = -1;
+  }
+  else
+  {
+    int fieldId = mAttributes[ column ];
+    const QgsFields& fields = layer()->pendingFields();
+    QStringList fldNames;
+    fldNames << fields[ fieldId ].name();
+
+    QgsFeatureIterator it = mLayerCache->getFeatures( QgsFeatureRequest().setFlags( QgsFeatureRequest::NoGeometry ).setSubsetOfAttributes( fldNames, fields ) );
+
+    QgsFeature f;
+    while ( it.nextFeature( f ) )
+    {
+      mFieldCache.insert( f.id(), f.attribute( fieldId ) );
+    }
+
+    mCachedField = fieldId;
+  }
+}
diff --git a/src/gui/attributetable/qgsattributetablemodel.h b/src/gui/attributetable/qgsattributetablemodel.h
@@ -22,6 +22,7 @@
 #include <QObject>
 #include <QHash>
 #include <QQueue>
+#include <QMap>
 
 #include "qgsvectorlayer.h" // QgsAttributeList
 #include "qgsvectorlayercache.h"
@@ -173,9 +174,20 @@ class GUI_EXPORT QgsAttributeTableModel: public QAbstractTableModel
     void executeAction( int action, const QModelIndex &idx ) const;
 
     /**
-     * return feature attributes at given index */
+     * Return the feature attributes at given model index
+     * @return feature attributes at given model index
+     */
     QgsFeature feature( const QModelIndex &idx ) const;
 
+    /**
+     * Caches the entire data for one column. This should be called prior to sorting,
+     * so the data does not have to be fetched for every single comparison.
+     * Specify -1 as column to invalidate the cache
+     *
+     * @param column The column index of the field to catch
+     */
+    void prefetchColumnData( int column );
+
   signals:
     /**
      * Model has been changed
@@ -245,6 +257,11 @@ class GUI_EXPORT QgsAttributeTableModel: public QAbstractTableModel
     virtual bool loadFeatureAtId( QgsFeatureId fid ) const;
 
     QgsFeatureRequest mFeatureRequest;
+
+    /** The currently cached column */
+    int mCachedField;
+    /** Allows to cache one specific column (used for sorting) */
+    QMap<QgsFeatureId, QVariant> mFieldCache;
 };