Allow access to feature attributes by name

Author: wonder-sk

python/core/qgsfeature.sip

@@ -39,11 +39,34 @@ class QgsFeature
   }
 %End
 
+    SIP_PYOBJECT __getitem__(const QString& name);
+%MethodCode
+  int fieldIdx = sipCpp->fieldNameIndex(*a0);
+  if (fieldIdx == -1)
+    PyErr_SetString(PyExc_KeyError, a0->toAscii());
+  else
+  {
+    QVariant* v = new QVariant( sipCpp->attributeMap().value(fieldIdx) );
+    sipRes = sipConvertFromInstance(v, sipClass_QVariant, Py_None);
+  }
+%End
+
     void __setitem__(int key, QVariant value);
 %MethodCode
   sipCpp->addAttribute(a0, *a1);
 %End
 
+    void __setitem__(const QString& key, QVariant value);
+%MethodCode
+  int fieldIdx = sipCpp->fieldNameIndex(*a0);
+  if (fieldIdx == -1)
+    PyErr_SetString(PyExc_KeyError, a0->toAscii());
+  else
+  {
+    sipCpp->addAttribute(fieldIdx, *a1);
+  }
+%End
+
     void __delitem__(int key);
 %MethodCode
   if (sipCpp->attributeMap().contains(a0))
@@ -52,6 +75,15 @@ class QgsFeature
     PyErr_SetString(PyExc_KeyError, QByteArray::number(a0));
 %End
 
+    void __delitem__(const QString& name);
+%MethodCode
+  int fieldIdx = sipCpp->fieldNameIndex(*a0);
+  if (fieldIdx == -1)
+    PyErr_SetString(PyExc_KeyError, a0->toAscii());
+  else
+    sipCpp->deleteAttribute(fieldIdx);
+%End
+
     //! Constructor
     QgsFeature( qint64 id = 0, QString typeName = "" );
 
@@ -162,5 +194,46 @@ class QgsFeature
      */
     void setGeometryAndOwnership( unsigned char * geom /Transfer/, size_t length );
 
+    /** Assign a field map with the feature to allow attribute access by attribute name
+     *  @note added in 2.0
+     */
+    void setFieldMap( const QgsFieldMap* fields );
+
+    /** Get associated field map. may be NULL
+     *  @note added in 2.0
+     */
+    const QgsFieldMap* fieldMap() const;
+
+    /** Insert a value into attribute. Returns false if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    bool addAttribute( const QString& name, QVariant value );
+
+    /** Change a value of an attribute. Returns false if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    bool changeAttribute( const QString& name, QVariant value );
+
+    /** Remove an attribute value. Returns false if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    bool deleteAttribute( const QString& name );
+
+    /** Lookup attribute value from attribute name. Returns invalid variant if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    QVariant attribute( const QString& name ) const;
+
+    /** Utility method to get attribute index from name. Returns -1 if field does not exist or field map is not associated.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    int fieldNameIndex( const QString& fieldName ) const;
+
+    
 }; // class QgsFeature
 

src/core/qgsfeature.cpp

@@ -14,6 +14,7 @@ email                : sherman at mrcc.com
  ***************************************************************************/
 
 #include "qgsfeature.h"
+#include "qgsfield.h"
 #include "qgsgeometry.h"
 #include "qgsrectangle.h"
 
@@ -28,6 +29,7 @@ QgsFeature::QgsFeature( QgsFeatureId id, QString typeName )
     , mValid( false )
     , mDirty( 0 )
     , mTypeName( typeName )
+    , mFields( 0 )
 {
   // NOOP
 }
@@ -40,6 +42,7 @@ QgsFeature::QgsFeature( QgsFeature const & rhs )
     , mValid( rhs.mValid )
     , mDirty( rhs.mDirty )
     , mTypeName( rhs.mTypeName )
+    , mFields( rhs.mFields )
 {
 
   // copy embedded geometry
@@ -60,6 +63,7 @@ QgsFeature & QgsFeature::operator=( QgsFeature const & rhs )
   mAttributes =  rhs.mAttributes;
   mValid =  rhs.mValid;
   mTypeName = rhs.mTypeName;
+  mFields = rhs.mFields;
 
   // make sure to delete the old geometry (if exists)
   if ( mGeometry && mOwnsGeometry )
@@ -218,3 +222,53 @@ void QgsFeature::clean()
 {
   mDirty = false;
 }
+
+
+bool QgsFeature::addAttribute( const QString& name, QVariant value )
+{
+  int fieldIdx = fieldNameIndex( name );
+  if ( fieldIdx == -1 )
+    return false;
+
+  mAttributes.insert( fieldIdx, value );
+  return true;
+}
+
+bool QgsFeature::changeAttribute( const QString& name, QVariant value )
+{
+  return addAttribute( name, value );
+}
+
+bool QgsFeature::deleteAttribute( const QString& name )
+{
+  int fieldIdx = fieldNameIndex( name );
+  if ( fieldIdx == -1 )
+    return false;
+
+  mAttributes.remove( fieldIdx );
+  return true;
+}
+
+QVariant QgsFeature::attribute( const QString& name ) const
+{
+  int fieldIdx = fieldNameIndex( name );
+  if ( fieldIdx == -1 )
+    return QVariant();
+
+  return mAttributes.value( fieldIdx );
+}
+
+int QgsFeature::fieldNameIndex( const QString& fieldName ) const
+{
+  if ( !mFields )
+    return -1;
+
+  for ( QgsFieldMap::const_iterator it = mFields->constBegin(); it != mFields->constEnd(); ++it )
+  {
+    if ( QString::compare( it->name(), fieldName, Qt::CaseInsensitive ) == 0 )
+    {
+      return it.key();
+    }
+  }
+  return -1;
+}

src/core/qgsfeature.h

@@ -94,6 +94,8 @@ typedef int QgsFeatureId;
 // key = field index, value = field value
 typedef QMap<int, QVariant> QgsAttributeMap;
 
+class QgsField;
+typedef QMap<int, QgsField> QgsFieldMap;
 
 /** \ingroup core
  * The feature class encapsulates a single feature including its id,
@@ -216,6 +218,46 @@ class CORE_EXPORT QgsFeature
      */
     void setGeometryAndOwnership( unsigned char * geom, size_t length );
 
+    /** Assign a field map with the feature to allow attribute access by attribute name
+     *  @note added in 2.0
+     */
+    void setFieldMap( const QgsFieldMap* fields ) { mFields = fields; }
+
+    /** Get associated field map. may be NULL
+     *  @note added in 2.0
+     */
+    const QgsFieldMap* fieldMap() const { return mFields; }
+
+    /** Insert a value into attribute. Returns false if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    bool addAttribute( const QString& name, QVariant value );
+
+    /** Change a value of an attribute. Returns false if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    bool changeAttribute( const QString& name, QVariant value );
+
+    /** Remove an attribute value. Returns false if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    bool deleteAttribute( const QString& name );
+
+    /** Lookup attribute value from attribute name. Returns invalid variant if attribute name could not be converted to index.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    QVariant attribute( const QString& name ) const;
+
+    /** Utility method to get attribute index from name. Returns -1 if field does not exist or field map is not associated.
+     *  Field map must be associated to make this work.
+     *  @note added in 2.0
+     */
+    int fieldNameIndex( const QString& fieldName ) const;
+
   private:
 
     //! feature id
@@ -246,6 +288,8 @@ class CORE_EXPORT QgsFeature
     /// feature type name
     QString mTypeName;
 
+    //! Optional field map for name-based attribute lookups
+    const QgsFieldMap* mFields;
 
 }; // class QgsFeature
 

src/providers/delimitedtext/qgsdelimitedtextprovider.cpp

@@ -545,7 +545,7 @@ bool QgsDelimitedTextProvider::nextFeature( QgsFeature& feature )
     // At this point the current feature values are valid
 
     feature.setValid( true );
-
+    feature.setFieldMap( &attributeFields ); // allow name-based attribute lookups
     feature.setFeatureId( mFid );
 
     if ( geom )

src/providers/gpx/qgsgpxprovider.cpp

@@ -157,6 +157,7 @@ bool QgsGPXProvider::nextFeature( QgsFeature& feature )
           feature.setGeometryAndOwnership(( unsigned char * )geo, sizeof( wkbPoint ) );
         }
         feature.setValid( true );
+        feature.setFieldMap( &attributeFields ); // allow name-based attribute lookups
 
         // add attributes if they are wanted
         for ( iter = mAttributesToFetch.begin(); iter != mAttributesToFetch.end(); ++iter )
@@ -248,6 +249,7 @@ bool QgsGPXProvider::nextFeature( QgsFeature& feature )
           feature.setFeatureId( rte->id );
           result = true;
           feature.setValid( true );
+          feature.setFieldMap( &attributeFields ); // allow name-based attribute lookups
 
           // add attributes if they are wanted
           for ( iter = mAttributesToFetch.begin(); iter != mAttributesToFetch.end(); ++iter )
@@ -364,6 +366,7 @@ bool QgsGPXProvider::nextFeature( QgsFeature& feature )
           result = true;
 
           feature.setValid( true );
+          feature.setFieldMap( &attributeFields ); // allow name-based attribute lookups
 
           // add attributes if they are wanted
           for ( iter = mAttributesToFetch.begin(); iter != mAttributesToFetch.end(); ++iter )

src/providers/grass/qgsgrassprovider.cpp

@@ -343,6 +343,7 @@ bool QgsGrassProvider::nextFeature( QgsFeature& feature )
 
   feature.setFeatureId( id );
   feature.clearAttributeMap();
+  feature.setFieldMap( &fields() ); // allow name-based attribute lookups
 
   // TODO int may be 64 bits (memcpy)
   if ( type & ( GV_POINTS | GV_LINES | GV_FACE ) ) /* points or lines */

src/providers/memory/qgsmemoryprovider.cpp

@@ -287,6 +287,7 @@ bool QgsMemoryProvider::nextFeature( QgsFeature& feature )
     feature = mSelectIterator.value();
     mSelectIterator++;
     feature.setValid( true );
+    feature.setFieldMap( &mFields ); // allow name-based attribute lookups
   }
 
   return hasFeature;
@@ -308,6 +309,7 @@ bool QgsMemoryProvider::featureAtId( QgsFeatureId featureId,
 
   feature = *it;
   feature.setValid( true );
+  feature.setFieldMap( &mFields ); // allow name-based attribute lookups
   return true;
 }
 

src/providers/mssql/qgsmssqlprovider.cpp

@@ -537,6 +537,7 @@ bool QgsMssqlProvider::nextFeature( QgsFeature& feature )
     }
 
     feature.setValid( true );
+    feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
     return true;
   }
   return false;

src/providers/ogr/qgsogrprovider.cpp

@@ -639,6 +639,7 @@ bool QgsOgrProvider::featureAtId( QgsFeatureId featureId,
   if ( !fet )
     return false;
 
+  feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
   feature.setFeatureId( OGR_F_GetFID( fet ) );
   feature.clearAttributeMap();
   // skip features without geometry
@@ -714,6 +715,7 @@ bool QgsOgrProvider::nextFeature( QgsFeature& feature )
     feature.setFeatureId( OGR_F_GetFID( fet ) );
     feature.clearAttributeMap();
     feature.setTypeName( featureTypeName );
+    feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
 
     /* fetch geometry */
     if ( mFetchGeom || mUseIntersect )

src/providers/osm/osmprovider.cpp

@@ -651,6 +651,7 @@ bool QgsOSMDataProvider::fetchNode( QgsFeature& feature, sqlite3_stmt* stmt, boo
 
   feature.setFeatureId( selId );
   feature.setValid( true );
+  feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
   return true;
 }
 
@@ -762,6 +763,7 @@ bool QgsOSMDataProvider::fetchWay( QgsFeature& feature, sqlite3_stmt* stmt, bool
   }
   feature.setFeatureId( selId );
   feature.setValid( true );
+  feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
   return true;
 }
 

src/providers/postgres/qgspostgresprovider.cpp

@@ -672,6 +672,7 @@ bool QgsPostgresProvider::nextFeature( QgsFeature& feature )
   mFetched++;
 
   feature.setValid( true );
+  feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
   return true;
 }
 
@@ -877,6 +878,7 @@ bool QgsPostgresProvider::featureAtId( QgsFeatureId featureId, QgsFeature& featu
   mConnectionRO->closeCursor( cursorName );
 
   feature.setValid( gotit );
+  feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
 
 #if 0
   if ( gotit )

src/providers/spatialite/qgsspatialiteprovider.cpp

@@ -705,6 +705,7 @@ bool QgsSpatiaLiteProvider::featureAtId( QgsFeatureId featureId, QgsFeature & fe
 
   sqlite3_finalize( stmt );
 
+  feature.setFieldMap( &attributeFields ); // allow name-based attribute lookups
   feature.setValid( true );
   return true;
 }
@@ -731,6 +732,7 @@ bool QgsSpatiaLiteProvider::nextFeature( QgsFeature & feature )
     return false;
   }
 
+  feature.setFieldMap( &attributeFields ); // allow name-based attribute lookups
   feature.setValid( true );
   return true;
 }

src/providers/sqlanywhere/qgssqlanywhereprovider.cpp

@@ -315,6 +315,7 @@ QgsSqlAnywhereProvider::nextFeature( QgsFeature & feature, SqlAnyStatement *stmt
 
   if ( ok )
   {
+    feature.setFieldMap( &mAttributeFields ); // allow name-based attribute lookups
     // iterate mAttributesToFetch
     feature.clearAttributeMap();
     for ( QgsAttributeList::const_iterator it = mAttributesToFetch.constBegin()

src/providers/wfs/qgswfsprovider.cpp

@@ -172,6 +172,7 @@ void QgsWFSProvider::copyFeature( QgsFeature* f, QgsFeature& feature, bool fetch
   //id and valid
   feature.setValid( true );
   feature.setFeatureId( f->id() );
+  feature.setFieldMap( &mFields ); // allow name-based attribute lookups
 }
 
 bool QgsWFSProvider::featureAtId( QgsFeatureId featureId,