edit widgets: keep default values of new feature's attributes until they are added

(fixes #12391 & #12386 & #13857)

(cherry picked from commit bfb8ab6)

Author: jef-n

python/gui/editorwidgets/core/qgseditorwidgetwrapper.sip

@@ -64,6 +64,15 @@ class QgsEditorWidgetWrapper : QObject
      */
     QgsField field();
 
+    /**
+     * Access the default value of the field.
+     *
+     * @return the default value of the field
+     *
+     * @see layer()
+     */
+    QVariant defaultValue();
+
     /**
      * Will return a wrapper for a given widget
      * @param widget The widget which was created by a wrapper

python/gui/qgsfieldvalidator.sip

@@ -6,7 +6,7 @@ class QgsFieldValidator : QValidator
 %End
 
   public:
-    QgsFieldValidator( QObject *parent, const QgsField &field, QString dateFormat = "yyyy-MM-dd" );
+    QgsFieldValidator( QObject *parent, const QgsField &field, QString defaultValue, QString dateFormat = "yyyy-MM-dd" );
     ~QgsFieldValidator();
 
     virtual State validate(QString & /In,Out/, int & /In,Out/) const = 0 /API=QString:2 - /;

src/gui/editorwidgets/core/qgseditorwidgetwrapper.cpp

@@ -15,6 +15,7 @@
 
 #include "qgseditorwidgetwrapper.h"
 #include "qgsvectorlayer.h"
+#include "qgsvectordataprovider.h"
 #include "qgsfield.h"
 
 #include <QWidget>
@@ -35,6 +36,11 @@ QgsField QgsEditorWidgetWrapper::field()
   return layer()->pendingFields()[mFieldIdx];
 }
 
+QVariant QgsEditorWidgetWrapper::defaultValue()
+{
+  return layer()->dataProvider()->defaultValue( mFieldIdx );
+}
+
 QgsEditorWidgetWrapper* QgsEditorWidgetWrapper::fromWidget( QWidget* widget )
 {
   return qobject_cast<QgsEditorWidgetWrapper*>( widget->property( "EWV2Wrapper" ).value<QgsWidgetWrapper*>() );

src/gui/editorwidgets/core/qgseditorwidgetwrapper.h

@@ -81,6 +81,15 @@ class GUI_EXPORT QgsEditorWidgetWrapper : public QgsWidgetWrapper
      */
     QgsField field();
 
+    /**
+     * Access the default value of the field.
+     *
+     * @return the default value of the field
+     *
+     * @see layer()
+     */
+    QVariant defaultValue();
+
     /**
      * Will return a wrapper for a given widget
      * @param widget The widget which was created by a wrapper

src/gui/editorwidgets/qgstexteditwrapper.cpp

@@ -59,6 +59,11 @@ QVariant QgsTextEditWrapper::value()
       v == QSettings().value( "qgis/nullValue", "NULL" ).toString() )
     return QVariant( field().type() );
 
+  if ( v == defaultValue().toString() )
+  {
+    return defaultValue();
+  }
+
   QVariant res( v );
   if ( field().convertCompatible( res ) )
     return res;
@@ -99,16 +104,22 @@ void QgsTextEditWrapper::initWidget( QWidget* editor )
 
   if ( mLineEdit )
   {
-    mLineEdit->setValidator( new QgsFieldValidator( mLineEdit, field() ) );
+    mLineEdit->setValidator( new QgsFieldValidator( mLineEdit, field(), defaultValue().toString() ) );
+
+    QVariant defVal = defaultValue();
+    if ( defVal.isNull() )
+    {
+      defVal = QSettings().value( "qgis/nullValue", "NULL" );
+    }
 
     QgsFilterLineEdit *fle = qobject_cast<QgsFilterLineEdit*>( mLineEdit );
     if ( field().type() == QVariant::Int || field().type() == QVariant::Double || field().type() == QVariant::LongLong || field().type() == QVariant::Date )
     {
-      mLineEdit->setPlaceholderText( QSettings().value( "qgis/nullValue", "NULL" ).toString() );
+      mLineEdit->setPlaceholderText( defVal.toString() );
     }
     else if ( fle )
     {
-      fle->setNullValue( QSettings().value( "qgis/nullValue", "NULL" ).toString() );
+      fle->setNullValue( defVal.toString() );
     }
 
     connect( mLineEdit, SIGNAL( textChanged( QString ) ), this, SLOT( valueChanged( QString ) ) );

src/gui/qgsfieldvalidator.cpp

@@ -29,9 +29,10 @@
 #include "qgslonglongvalidator.h"
 #include "qgsfield.h"
 
-QgsFieldValidator::QgsFieldValidator( QObject *parent, const QgsField &field, QString dateFormat )
+QgsFieldValidator::QgsFieldValidator( QObject *parent, const QgsField &field, QString defaultValue, QString dateFormat )
     : QValidator( parent )
     , mField( field )
+    , mDefaultValue( defaultValue )
     , mDateFormat( dateFormat )
 {
   switch ( mField.type() )
@@ -105,6 +106,9 @@ QValidator::State QgsFieldValidator::validate( QString &s, int &i ) const
     return Acceptable;
   }
 
+  if ( s == mDefaultValue )
+    return Acceptable;
+
   // delegate to the child validator if any
   if ( mValidator )
   {
@@ -115,10 +119,10 @@ QValidator::State QgsFieldValidator::validate( QString &s, int &i ) const
   {
     // allow to enter the NULL representation, which might be
     // longer than the actual field
-    if ( mNullValue.size() > 0 &&
-         s.size() > 0 &&
-         s.size() < mNullValue.size() &&
-         s == mNullValue.left( s.size() ) )
+    if ( mNullValue.size() > 0 && s.size() > 0 && s.size() < mNullValue.size() && s == mNullValue.left( s.size() ) )
+      return Intermediate;
+
+    if ( mDefaultValue.size() > 0 && s.size() > 0 && s.size() < mDefaultValue.size() && s == mDefaultValue.left( s.size() ) )
       return Intermediate;
 
     if ( s == mNullValue )
@@ -146,7 +150,7 @@ void QgsFieldValidator::fixup( QString &s ) const
   {
     mValidator->fixup( s );
   }
-  else if ( mField.type() == QVariant::String && mField.length() > 0 && s.size() > mField.length() )
+  else if ( mField.type() == QVariant::String && mField.length() > 0 && s.size() > mField.length() && s != mDefaultValue )
   {
     // if the value is longer, this must be a partial NULL representation
     s = mNullValue;

src/gui/qgsfieldvalidator.h

@@ -31,7 +31,7 @@ class GUI_EXPORT QgsFieldValidator : public QValidator
     Q_OBJECT
 
   public:
-    QgsFieldValidator( QObject *parent, const QgsField &field, QString dateFormat = "yyyy-MM-dd" );
+    QgsFieldValidator( QObject *parent, const QgsField &field, QString defaultValue, QString dateFormat = "yyyy-MM-dd" );
     ~QgsFieldValidator();
 
     virtual State validate( QString &, int & ) const override;
@@ -46,6 +46,7 @@ class GUI_EXPORT QgsFieldValidator : public QValidator
     QValidator *mValidator;
     QgsField mField;
     QString mNullValue;
+    QString mDefaultValue;
     QString mDateFormat;
 };
 

src/providers/postgres/qgspostgresprovider.cpp

@@ -3407,10 +3407,10 @@ QGISEXTERN bool saveStyle( const QString& uri, const QString& qmlStyle, const QS
   {
     res = conn->PQexec( "CREATE TABLE layer_styles("
                         "id SERIAL PRIMARY KEY"
-                        ",f_table_catalog varchar(256)"
-                        ",f_table_schema varchar(256)"
-                        ",f_table_name varchar(256)"
-                        ",f_geometry_column varchar(256)"
+                        ",f_table_catalog varchar"
+                        ",f_table_schema varchar"
+                        ",f_table_name varchar"
+                        ",f_geometry_column varchar"
                         ",styleName varchar(30)"
                         ",styleQML xml"
                         ",styleSLD xml"