Fields' layer listed into a QListWidget in PyQGIS

Question

I use a QgsMapLayerComboBox nested with a QgsFieldComboBox in Qt. The problem is that I can select only one field with the field combobox and I need to select several fields.

self.dlg.mMapLayerComboBox_2.layerChanged['QgsMapLayer*'].connect(self.dlg.mFieldComboBox_2.setLayer)

That's why instead of using a Combobox I would like to replace the FieldComboBox by a QListWidget.

How can I fill a QListWidget by the list of field of the Layer selected by MapLayerCombobox?

Answer 1

Here is an example which you can run in an editor in the Python console. This should provide you with an example of adding items to the list widget from a list of field names from the current layer in the map layer combo box and updating the fields whenever the layer is changed; allowing multiple selections with:

self.fld_list.setSelectionMode(QListWidget.ExtendedSelection)

clearing the selection, and retrieving the QgsField objects from the list widget selected items. My example creates a dictionary of field names and field objects by calling the text() method on the QListWidgetItem objects returned by the selectedItems() method.

class Dlg(QDialog):

    def __init__(self):
        QDialog.__init__(self)
        self.layout = QGridLayout(self)
        self.cb_layer = QgsMapLayerComboBox()
        self.cb_layer.setFilters(QgsMapLayerProxyModel.VectorLayer)
        self.cb_layer.layerChanged.connect(self.layer_changed)
        self.fld_list = QListWidget(self)
        self.fld_list.setSelectionMode(QListWidget.ExtendedSelection)
        self.fld_list.addItems([f.name() for f in self.cb_layer.currentLayer().fields()])
        self.btn1 = QPushButton('Clear selection', self)
        self.btn1.clicked.connect(lambda: self.fld_list.clearSelection())
        self.te1 = QTextEdit(self)
        self.btn2 = QPushButton('Retrieve selected fields', self)
        self.btn2.clicked.connect(self.get_selection)
        self.layout.addWidget(self.cb_layer, 0, 0)
        self.layout.addWidget(self.fld_list, 1, 0)
        self.layout.addWidget(self.btn1, 2, 0)
        self.layout.addWidget(self.te1, 3, 0)
        self.layout.addWidget(self.btn2, 4, 0)

    def layer_changed(self, layer):
        self.fld_list.clear()
        flds = [f.name() for f in layer.fields()]
        self.fld_list.addItems(flds)

    def get_selection(self):
        inds = [i.text() for i in self.fld_list.selectedItems()]
        flds = {}
        for i in inds:
            flds[i] = [f for f in self.cb_layer.currentLayer().fields() if f.name() == i][0]
        self.te1.setText(str(flds))


W = Dlg()
W.show()

Result: