Move storage of field alias and default value to QgsField

This is a partial implementation - QMaps are still used internally
within QgsVectorLayer to track the alias/default values
between attribute edit operations.

Sponsored by DB Fahrwegdienste GmbH

Author: nyalldawson

python/core/qgsfield.sip

@@ -42,9 +42,20 @@ class QgsField
     bool operator==( const QgsField& other ) const;
     bool operator!=( const QgsField& other ) const;
 
-    //! Gets the name of the field
+    /** Returns the name of the field.
+     * @see setName()
+     * @see displayName()
+     */
     QString name() const;
 
+    /** Returns the name to use when displaying this field. This will be the
+     * field alias if set, otherwise the field name.
+     * @see name()
+     * @see alias()
+     * @note added in QGIS 3.0
+     */
+    QString displayName() const;
+
     //! Gets variant type of the field as it will be retrieved from data source
     QVariant::Type type() const;
 
@@ -115,6 +126,36 @@ class QgsField
      */
     void setComment( const QString& comment );
 
+    /** Returns the expression used when calculating the default value for the field.
+     * @returns expression evaluated when calculating default values for field, or an
+     * empty string if no default is set
+     * @note added in QGIS 3.0
+     * @see setDefaultValueExpression()
+     */
+    QString defaultValueExpression() const;
+
+    /** Sets an expression to use when calculating the default value for the field.
+     * @param expression expression to evaluate when calculating default values for field. Pass
+     * an empty expression to clear the default.
+     * @note added in QGIS 3.0
+     * @see defaultValueExpression()
+     */
+    void setDefaultValueExpression( const QString& expression );
+
+    /** Returns the alias for the field (the friendly displayed name of the field ),
+     * or an empty string if there is no alias.
+     * @see setAlias()
+     * @note added in QGIS 3.0
+     */
+    QString alias() const;
+
+    /** Sets the alias for the field (the friendly displayed name of the field ).
+     * @param alias field alias, or empty string to remove an existing alias
+     * @see alias()
+     * @note added in QGIS 3.0
+     */
+    void setAlias( const QString& alias );
+
     /** Formats string for display*/
     QString displayString( const QVariant& v ) const;
 

src/app/qgsfieldsproperties.cpp

@@ -343,7 +343,7 @@ void QgsFieldsProperties::setRow( int row, int idx, const QgsField& field )
   setConfigForRow( row, cfg );
 
   //set the alias for the attribute
-  mFieldsList->setItem( row, attrAliasCol, new QTableWidgetItem( mLayer->attributeAlias( idx ) ) );
+  mFieldsList->setItem( row, attrAliasCol, new QTableWidgetItem( field.alias() ) );
 
   //published WMS/WFS attributes
   QTableWidgetItem* wmsAttrItem = new QTableWidgetItem();

src/core/qgsfield.cpp

@@ -86,6 +86,14 @@ QString QgsField::name() const
   return d->name;
 }
 
+QString QgsField::displayName() const
+{
+  if ( !d->alias.isEmpty() )
+    return d->alias;
+  else
+    return d->name;
+}
+
 QVariant::Type QgsField::type() const
 {
   return d->type;
@@ -151,6 +159,26 @@ void QgsField::setComment( const QString& comment )
   d->comment = comment;
 }
 
+QString QgsField::defaultValueExpression() const
+{
+  return d->defaultValueExpression;
+}
+
+void QgsField::setDefaultValueExpression( const QString& expression )
+{
+  d->defaultValueExpression = expression;
+}
+
+QString QgsField::alias() const
+{
+  return d->alias;
+}
+
+void QgsField::setAlias( const QString& alias )
+{
+  d->alias = alias;
+}
+
 /***************************************************************************
  * This class is considered CRITICAL and any change MUST be accompanied with
  * full unit tests in testqgsfield.cpp.
@@ -252,20 +280,24 @@ QDataStream& operator<<( QDataStream& out, const QgsField& field )
   out << field.length();
   out << field.precision();
   out << field.comment();
+  out << field.alias();
+  out << field.defaultValueExpression();
   return out;
 }
 
 QDataStream& operator>>( QDataStream& in, QgsField& field )
 {
   quint32 type, length, precision;
-  QString name, typeName, comment;
-  in >> name >> type >> typeName >> length >> precision >> comment;
+  QString name, typeName, comment, alias, defaultValueExpression;
+  in >> name >> type >> typeName >> length >> precision >> comment >> alias >> defaultValueExpression;
   field.setName( name );
   field.setType( static_cast< QVariant::Type >( type ) );
   field.setTypeName( typeName );
   field.setLength( static_cast< int >( length ) );
   field.setPrecision( static_cast< int >( precision ) );
   field.setComment( comment );
+  field.setAlias( alias );
+  field.setDefaultValueExpression( defaultValueExpression );
   return in;
 }
 

src/core/qgsfield.h

@@ -46,10 +46,12 @@ class CORE_EXPORT QgsField
     Q_GADGET
 
     Q_PROPERTY( bool isNumeric READ isNumeric )
-    Q_PROPERTY( int length READ length )
-    Q_PROPERTY( int precision READ precision )
-    Q_PROPERTY( QString comment READ comment )
-    Q_PROPERTY( QString name READ name )
+    Q_PROPERTY( int length READ length WRITE setLength )
+    Q_PROPERTY( int precision READ precision WRITE setPrecision )
+    Q_PROPERTY( QString comment READ comment WRITE setComment )
+    Q_PROPERTY( QString name READ name WRITE setName )
+    Q_PROPERTY( QString alias READ alias WRITE setAlias )
+    Q_PROPERTY( QString defaultValueExpression READ defaultValueExpression WRITE setDefaultValueExpression )
 
   public:
     /** Constructor. Constructs a new QgsField object.
@@ -84,9 +86,20 @@ class CORE_EXPORT QgsField
     bool operator==( const QgsField& other ) const;
     bool operator!=( const QgsField& other ) const;
 
-    //! Gets the name of the field
+    /** Returns the name of the field.
+     * @see setName()
+     * @see displayName()
+     */
     QString name() const;
 
+    /** Returns the name to use when displaying this field. This will be the
+     * field alias if set, otherwise the field name.
+     * @see name()
+     * @see alias()
+     * @note added in QGIS 3.0
+     */
+    QString displayName() const;
+
     //! Gets variant type of the field as it will be retrieved from data source
     QVariant::Type type() const;
 
@@ -157,6 +170,36 @@ class CORE_EXPORT QgsField
      */
     void setComment( const QString& comment );
 
+    /** Returns the expression used when calculating the default value for the field.
+     * @returns expression evaluated when calculating default values for field, or an
+     * empty string if no default is set
+     * @note added in QGIS 3.0
+     * @see setDefaultValueExpression()
+     */
+    QString defaultValueExpression() const;
+
+    /** Sets an expression to use when calculating the default value for the field.
+     * @param expression expression to evaluate when calculating default values for field. Pass
+     * an empty expression to clear the default.
+     * @note added in QGIS 3.0
+     * @see defaultValueExpression()
+     */
+    void setDefaultValueExpression( const QString& expression );
+
+    /** Returns the alias for the field (the friendly displayed name of the field ),
+     * or an empty string if there is no alias.
+     * @see setAlias()
+     * @note added in QGIS 3.0
+     */
+    QString alias() const;
+
+    /** Sets the alias for the field (the friendly displayed name of the field ).
+     * @param alias field alias, or empty string to remove an existing alias
+     * @see alias()
+     * @note added in QGIS 3.0
+     */
+    void setAlias( const QString& alias );
+
     /** Formats string for display*/
     QString displayString( const QVariant& v ) const;
 

src/core/qgsfield_p.h

@@ -65,6 +65,8 @@ class QgsFieldPrivate : public QSharedData
         , length( other.length )
         , precision( other.precision )
         , comment( other.comment )
+        , alias( other.alias )
+        , defaultValueExpression( other.defaultValueExpression )
     {
     }
 
@@ -73,7 +75,8 @@ class QgsFieldPrivate : public QSharedData
     bool operator==( const QgsFieldPrivate& other ) const
     {
       return (( name == other.name ) && ( type == other.type )
-              && ( length == other.length ) && ( precision == other.precision ) );
+              && ( length == other.length ) && ( precision == other.precision )
+              && ( alias == other.alias ) && ( defaultValueExpression == other.defaultValueExpression ) );
     }
 
     //! Name
@@ -93,6 +96,12 @@ class QgsFieldPrivate : public QSharedData
 
     //! Comment
     QString comment;
+
+    //! Alias for field name (friendly name shown to users)
+    QString alias;
+
+    //! Default value expression
+    QString defaultValueExpression;
 };