27 #include <QStringListModel>    67     return fieldName + 
" IS NULL";
    69     return fieldName + 
" IS NOT NULL";
    79     case QVariant::Double:
    80     case QVariant::LongLong:
    81     case QVariant::ULongLong:
    84         return fieldName + 
'=' + v.toString();
    86         return fieldName + 
"<>" + v.toString();
    93         return fieldName + 
"='" + v.toString() + 
'\'';
    95         return fieldName + 
"<>'" + v.toString() + 
'\'';
   115     mWidget->setEnabled( enabled );
   126   if ( !value.isValid() )
   147   if ( exp == nullValue )
   153     str = QStringLiteral( 
"%1 = '%3'" )
   155                 exp.replace( 
'\'', QLatin1String( 
"''" ) )
   181   if ( 
config( QStringLiteral( 
"FilterFields" ), QVariant() ).isValid() )
 
static QString quotedColumnRef(QString name)
Returns a quoted column reference (in double quotes) 
 
This class is a composition of two QSettings instances: 
 
Map canvas is a class for displaying all GIS data types on a canvas. 
 
QgsField at(int i) const
Gets field at particular index (must be in range 0..N-1) 
 
QgsFields fields() const FINAL
Returns the list of fields of this layer. 
 
static QString nullRepresentation()
This string is used to represent the value NULL throughout QGIS. 
 
QgsRelationManager relationManager
 
static QgsProject * instance()
Returns the QgsProject singleton instance. 
 
Q_INVOKABLE QgsRelation relation(const QString &id) const
Gets access to a relation by its id. 
 
Represents a vector layer which manages a vector based data sets.