How to display a selected field unique values from a selected layer as rows headers in QTableWidget using python for a QGIS plugin? - pyqt4

Question

To build a form in Qt Designer for a QGIS plugin that does the following:
After the user has selected a layer and a field, from comboboxes, the unique values of this field to be displayed as rows headers in QTableWidget using python

Answer 1

def showdlg(self):
# show the dialog - ui file
self.dlg.show()
# Get the layers names
legendInterface = self.iface.legendInterface()
listLayerName = [i.name() for i in legendInterface.layers() if i.type() == QgsMapLayer.VectorLayer]
# Add all these layer names to the layer combobox
self.dlg.cmbLayer.addItems(listLayerName)
# When user selects a layer from the layer combobox
# insert the corresponding fields names to the field combobox
self.dlg.cmbLayer.currentIndexChanged[int].connect(self.FieldsNamestoFieldCombo)
# When user selects a field from the field combobox,
# insert the unique values of this field as the table' s rows names
self.dlg.cmbField.currentIndexChanged[int].connect(self.FieldUniqueValuestoTable)
def FieldsNamestoFieldCombo(self, index):
# get list of all vector layers in QGIS
legendInterface = self.iface.legendInterface()
listLayers = [layer for layer in legendInterface.layers() if layer.type() == QgsMapLayer.VectorLayer]
# get name of selected layer
provider = listLayers[index].dataProvider()
fields = provider.fields()
listFieldNames = [field.name() for field in fields]
# clear the combo box comboFieldList
self.dlg.cmbField.clear()
# add all these field names to combo box comboFieldList
self.dlg.cmbField.addItems(listFieldNames)
def FieldUniqueValuestoTable(self, index):
# Get the selected layer id
layer_id = getVectorLayerByName(self.dlg.cmbLayer.currentText())
# Get the selected field name and id
field = self.dlg.cmbField.currentText()
field_index = layer_id.fieldNameIndex(field)
#Get the unique values of the selected field
un_values = layer_id.uniqueValues(field_index)
# Count the number of unique values
un_values_length = len(un_values)
# Set the table to have as many rows as the number of unique values
# of the selected field
self.dlg.tableWidget.setRowCount(un_values_length)
# Make a new list that holds the unique values as strings
un_values_string_list = []
for i in range(un_values_length):
a = str(un_values[i])
un_values_string_list.append(a)
# Set the tables rows names to be the unique values
self.dlg.tableWidget.setVerticalHeaderLabels(un_values_string_list)