Add merge policies

python/PyQt6/core/auto_additions/qgis.py

@@ -6928,6 +6928,11 @@
 Qgis.FieldDomainMergePolicy.DefaultValue.__doc__ = "Use default field value"
 Qgis.FieldDomainMergePolicy.Sum.__doc__ = "Sum of values"
 Qgis.FieldDomainMergePolicy.GeometryWeighted.__doc__ = "New values are computed as the weighted average of the source values"
+Qgis.FieldDomainMergePolicy.UnsetField.__doc__ = "Clears the field value so that the data provider backend will populate using any backend triggers or similar logic \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.LargestGeometry.__doc__ = "Use value from the feature with the largest geometry \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.MinimumValue.__doc__ = "Use the minimum value from the features-to-be-merged \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.MaximumValue.__doc__ = "Use the maximum value from the features-to-be-merged \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.SetToNull.__doc__ = "Use a null value \n.. versionadded:: 3.44"
 Qgis.FieldDomainMergePolicy.__doc__ = """Merge policy for field domains.
 
 When a feature is built by merging multiple features, defines how the value of
@@ -6938,6 +6943,26 @@
 * ``DefaultValue``: Use default field value
 * ``Sum``: Sum of values
 * ``GeometryWeighted``: New values are computed as the weighted average of the source values
+* ``UnsetField``: Clears the field value so that the data provider backend will populate using any backend triggers or similar logic
+
+  .. versionadded:: 3.44
+
+* ``LargestGeometry``: Use value from the feature with the largest geometry
+
+  .. versionadded:: 3.44
+
+* ``MinimumValue``: Use the minimum value from the features-to-be-merged
+
+  .. versionadded:: 3.44
+
+* ``MaximumValue``: Use the maximum value from the features-to-be-merged
+
+  .. versionadded:: 3.44
+
+* ``SetToNull``: Use a null value
+
+  .. versionadded:: 3.44
+
 
 """
 # --

python/PyQt6/core/auto_generated/qgis.sip.in

@@ -2112,6 +2112,11 @@ The development version
       DefaultValue,
       Sum,
       GeometryWeighted,
+      UnsetField,
+      LargestGeometry,
+      MinimumValue,
+      MaximumValue,
+      SetToNull,
     };
 
     enum class FieldDuplicatePolicy /BaseType=IntEnum/

python/PyQt6/core/auto_generated/qgsfield.sip.in

@@ -531,6 +531,26 @@ be handled during a duplicate operation.
 .. seealso:: :py:func:`duplicatePolicy`
 
 .. versionadded:: 3.38
+%End
+
+    Qgis::FieldDomainMergePolicy mergePolicy() const /HoldGIL/;
+%Docstring
+Returns the field's merge policy, which indicates how field values should
+be handled during a merge operation.
+
+.. seealso:: :py:func:`setMergePolicy`
+
+.. versionadded:: 3.44
+%End
+
+    void setMergePolicy( Qgis::FieldDomainMergePolicy policy ) /HoldGIL/;
+%Docstring
+Sets the field's merge ``policy``, which indicates how field values should
+be handled during a merge operation.
+
+.. seealso:: :py:func:`mergePolicy`
+
+.. versionadded:: 3.44
 %End
 
     SIP_PYOBJECT __repr__();

python/PyQt6/core/auto_generated/vector/qgsvectorlayer.sip.in

@@ -1953,6 +1953,27 @@ Sets a duplicate ``policy`` for the field with the specified index.
     }
 %End
 
+    void setFieldMergePolicy( int index, Qgis::FieldDomainMergePolicy policy );
+%Docstring
+Sets a merge ``policy`` for the field with the specified index.
+
+:raises KeyError: if no field with the specified index exists
+
+.. versionadded:: 3.44
+%End
+
+%MethodCode
+    if ( a0 < 0 || a0 >= sipCpp->fields().count() )
+    {
+      PyErr_SetString( PyExc_KeyError, QByteArray::number( a0 ) );
+      sipIsErr = 1;
+    }
+    else
+    {
+      sipCpp->setFieldMergePolicy( a0, a1 );
+    }
+%End
+
  QSet<QString> excludeAttributesWms() const /Deprecated="Since 3.16. Use fields().configurationFlags() instead."/;
 %Docstring
 A set of attributes that are not advertised in WMS requests with QGIS server.

python/core/auto_additions/qgis.py

@@ -6862,6 +6862,11 @@
 Qgis.FieldDomainMergePolicy.DefaultValue.__doc__ = "Use default field value"
 Qgis.FieldDomainMergePolicy.Sum.__doc__ = "Sum of values"
 Qgis.FieldDomainMergePolicy.GeometryWeighted.__doc__ = "New values are computed as the weighted average of the source values"
+Qgis.FieldDomainMergePolicy.UnsetField.__doc__ = "Clears the field value so that the data provider backend will populate using any backend triggers or similar logic \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.LargestGeometry.__doc__ = "Use value from the feature with the largest geometry \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.MinimumValue.__doc__ = "Use the minimum value from the features-to-be-merged \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.MaximumValue.__doc__ = "Use the maximum value from the features-to-be-merged \n.. versionadded:: 3.44"
+Qgis.FieldDomainMergePolicy.SetToNull.__doc__ = "Use a null value \n.. versionadded:: 3.44"
 Qgis.FieldDomainMergePolicy.__doc__ = """Merge policy for field domains.
 
 When a feature is built by merging multiple features, defines how the value of
@@ -6872,6 +6877,26 @@
 * ``DefaultValue``: Use default field value
 * ``Sum``: Sum of values
 * ``GeometryWeighted``: New values are computed as the weighted average of the source values
+* ``UnsetField``: Clears the field value so that the data provider backend will populate using any backend triggers or similar logic
+
+  .. versionadded:: 3.44
+
+* ``LargestGeometry``: Use value from the feature with the largest geometry
+
+  .. versionadded:: 3.44
+
+* ``MinimumValue``: Use the minimum value from the features-to-be-merged
+
+  .. versionadded:: 3.44
+
+* ``MaximumValue``: Use the maximum value from the features-to-be-merged
+
+  .. versionadded:: 3.44
+
+* ``SetToNull``: Use a null value
+
+  .. versionadded:: 3.44
+
 
 """
 # --

python/core/auto_generated/qgis.sip.in

@@ -2112,6 +2112,11 @@ The development version
       DefaultValue,
       Sum,
       GeometryWeighted,
+      UnsetField,
+      LargestGeometry,
+      MinimumValue,
+      MaximumValue,
+      SetToNull,
     };
 
     enum class FieldDuplicatePolicy

python/core/auto_generated/qgsfield.sip.in

@@ -531,6 +531,26 @@ be handled during a duplicate operation.
 .. seealso:: :py:func:`duplicatePolicy`
 
 .. versionadded:: 3.38
+%End
+
+    Qgis::FieldDomainMergePolicy mergePolicy() const /HoldGIL/;
+%Docstring
+Returns the field's merge policy, which indicates how field values should
+be handled during a merge operation.
+
+.. seealso:: :py:func:`setMergePolicy`
+
+.. versionadded:: 3.44
+%End
+
+    void setMergePolicy( Qgis::FieldDomainMergePolicy policy ) /HoldGIL/;
+%Docstring
+Sets the field's merge ``policy``, which indicates how field values should
+be handled during a merge operation.
+
+.. seealso:: :py:func:`mergePolicy`
+
+.. versionadded:: 3.44
 %End
 
     SIP_PYOBJECT __repr__();

python/core/auto_generated/vector/qgsvectorlayer.sip.in

@@ -1953,6 +1953,27 @@ Sets a duplicate ``policy`` for the field with the specified index.
     }
 %End
 
+    void setFieldMergePolicy( int index, Qgis::FieldDomainMergePolicy policy );
+%Docstring
+Sets a merge ``policy`` for the field with the specified index.
+
+:raises KeyError: if no field with the specified index exists
+
+.. versionadded:: 3.44
+%End
+
+%MethodCode
+    if ( a0 < 0 || a0 >= sipCpp->fields().count() )
+    {
+      PyErr_SetString( PyExc_KeyError, QByteArray::number( a0 ) );
+      sipIsErr = 1;
+    }
+    else
+    {
+      sipCpp->setFieldMergePolicy( a0, a1 );
+    }
+%End
+
  QSet<QString> excludeAttributesWms() const /Deprecated="Since 3.16. Use fields().configurationFlags() instead."/;
 %Docstring
 A set of attributes that are not advertised in WMS requests with QGIS server.

src/app/browser/qgsinbuiltdataitemproviders.cpp

@@ -2244,6 +2244,21 @@ QString QgsFieldDomainDetailsWidget::htmlMetadata( QgsFieldDomain *domain, const
     case Qgis::FieldDomainMergePolicy::GeometryWeighted:
       metadata += tr( "Use geometry weighted value" );
       break;
+    case Qgis::FieldDomainMergePolicy::UnsetField:
+      metadata += tr( "Unset field" );
+      break;
+    case Qgis::FieldDomainMergePolicy::LargestGeometry:
+      metadata += tr( "Largest geometry" );
+      break;
+    case Qgis::FieldDomainMergePolicy::MaximumValue:
+      metadata += tr( "Maximum value" );
+      break;
+    case Qgis::FieldDomainMergePolicy::MinimumValue:
+      metadata += tr( "Minimum value" );
+      break;
+    case Qgis::FieldDomainMergePolicy::SetToNull:
+      metadata += tr( "Skip attribute" );
+      break;
   }
 
   metadata += QLatin1String( "</table>\n<br><br>" );

src/app/qgisapp.cpp

@@ -9451,9 +9451,8 @@ void QgisApp::mergeAttributesOfSelectedFeatures()
   QgsFeatureList featureList = vl->selectedFeatures();
 
   //merge the attributes together
-  QgsMergeAttributesDialog d( featureList, vl, mapCanvas() );
-  //initialize dialog with all columns set to skip
-  d.setAllToSkip();
+  QgsMergeAttributesDialog d( featureList, vl, mapCanvas(), true );
+
   if ( d.exec() == QDialog::Rejected )
   {
     return;