Populating ComboBox with unique features in selected attribute field using PyQGIS

Question

I am creating a plugin in QGIS where I want to read a Vector layer --> Select attribute column --> list unique values within the chosen attribute column in the selected attribute from the column.

I have been successful with the two first steps, but not with the third.

This is the code used so far, but I cannot get further than this.

self.layerComboManagerPoint = QgsMapLayerComboBox(self.dlg.comboBoxVector)
self.layerComboManagerPoint.setCurrentIndex(-1)
self.layerComboManagerPoint.setFilters(QgsMapLayerProxyModel.PolygonLayer)
self.layerComboManagerPoint.setFixedWidth(175)
self.layerComboManagerPointField = QgsFieldComboBox(self.dlg.comboBoxField)
self.layerComboManagerPointField.setFilters(QgsFieldProxyModel.AllTypes) 
self.layerComboManagerPoint.layerChanged.connect(self.layerComboManagerPointField.setLayer)

I have tried googling, but I might just not have a reasonable word to google on.

enter image description here

Answer 1

Add the highlighted lines to your script:

self.layerComboManagerPoint = QgsMapLayerComboBox(self.dlg.comboBoxVector)
self.layerComboManagerPoint.setCurrentIndex(-1)
self.layerComboManagerPoint.setFilters(QgsMapLayerProxyModel.PolygonLayer)
self.layerComboManagerPoint.setFixedWidth(175)
self.layerComboManagerPointField = QgsFieldComboBox(self.dlg.comboBoxField)
self.layerComboManagerPointField.setFilters(QgsFieldProxyModel.AllTypes) 
self.layerComboManagerPoint.layerChanged.connect(self.layerComboManagerPointField.setLayer)
################## ADD THESE LINES #########################
def field_changed(field):
 # get current layer
 layer = self.layerComboManagerPoint.currentLayer()
 # get index of the field
 i = layer.fields().indexOf(field)
 # get unique values
 unique_values = layer.uniqueValues(i) 
 # remove all values from comboBoxAttribute
 self.dlg.comboBoxAttribute.clear() 
 # add unique values
 self.dlg.comboBoxAttribute.addItems(unique_values) 
self.layerComboManagerPointField.fieldChanged.connect(field_changed) 
#############################################################

• gusbacos: OK, it works fine, however, I also now understand that I need to be able to read other types than 'string'. I tried self.dlg.comboBoxAttributesetFilters(QgsMapLayerProxyModel.AllTypes) But with no luck. Do you have any solution to this too?