def getParamValues(self):
        if self.mUpdateExistingGroupBox.isChecked():
            fieldName = self.mExistingFieldComboBox.currentText()
        else:
            fieldName = self.mOutputFieldNameLineEdit.text()

        layer = self.cmbInputLayer.currentLayer()

        context = dataobjects.createContext()

        parameters = {}
        parameters['INPUT'] = layer
        parameters['FIELD_NAME'] = fieldName
        parameters['FIELD_TYPE'] = self.mOutputFieldTypeComboBox.currentIndex()
        parameters['FIELD_LENGTH'] = self.mOutputFieldWidthSpinBox.value()
        parameters['FIELD_PRECISION'] = self.mOutputFieldPrecisionSpinBox.value()
        parameters['NEW_FIELD'] = self.mNewFieldGroupBox.isChecked()
        parameters['FORMULA'] = self.builder.expressionText()
        output = QgsProcessingOutputLayerDefinition()
        if self.leOutputFile.text().strip():
            output.sink = QgsProperty.fromValue(self.leOutputFile.text().strip())
        else:
            output.sink = QgsProperty.fromValue('memory:')
        output.destinationProject = context.project()
        parameters['OUTPUT'] = output

        ok, msg = self.alg.checkParameterValues(parameters, context)
        if not ok:
            QMessageBox.warning(
                self, self.tr('Unable to execute algorithm'), msg)
            return {}
        return parameters

    def getConsoleCommands(self, parameters, context, feedback):
        arguments = []
        arguments.append('-resolution')
        arguments.append(self.RESOLUTION_OPTIONS[self.parameterAsEnum(parameters, self.RESOLUTION, context)])
        if self.parameterAsBool(parameters, buildvrt.SEPARATE, context):
            arguments.append('-separate')
        if self.parameterAsBool(parameters, buildvrt.PROJ_DIFFERENCE, context):
            arguments.append('-allow_projection_difference')
        # Always write input files to a text file in case there are many of them and the
        # length of the command will be longer then allowed in command prompt
        listFile = os.path.join(QgsProcessingUtils.tempFolder(), 'buildvrtInputFiles.txt')
        with open(listFile, 'w') as f:
            layers = []
            for l in self.parameterAsLayerList(parameters, self.INPUT, context):
                layers.append(l.source())
            f.write('\n'.join(layers))
        arguments.append('-input_file_list')
        arguments.append(listFile)

        out = self.parameterAsOutputLayer(parameters, self.OUTPUT, context)
        # Ideally the file extensions should be limited to just .vrt but I'm not sure how
        # to do it simply so instead a check is performed.
        _, ext = os.path.splitext(out)
        if not ext.lower() == '.vrt':
            out = out[:-len(ext)] + '.vrt'
            if isinstance(parameters[self.OUTPUT], QgsProcessingOutputLayerDefinition):
                output_def = QgsProcessingOutputLayerDefinition(parameters[self.OUTPUT])
                output_def.sink = QgsProperty.fromValue(out)
                self.setOutputValue(self.OUTPUT, output_def)
            else:
                self.setOutputValue(self.OUTPUT, out)
        arguments.append(out)

        return ['gdalbuildvrt', GdalUtils.escapeAndJoin(arguments)]

    def getValue(self):
        key = None
        if self.use_temporary and isinstance(self.parameter, QgsProcessingParameterFeatureSink):
            key = QgsProcessing.TEMPORARY_OUTPUT
        elif self.use_temporary and not self.default_selection:
            key = QgsProcessing.TEMPORARY_OUTPUT
        else:
            key = self.leText.text()

        if not key and self.parameter.flags() & QgsProcessingParameterDefinition.FlagOptional:
            return None

        if key and not key == QgsProcessing.TEMPORARY_OUTPUT \
                and not key.startswith('memory:') \
                and not key.startswith('ogr:') \
                and not key.startswith('postgres:') \
                and not key.startswith('postgis:'):
            # output should be a file path
            folder = QFileInfo(key).path()
            if folder == '.':
                # output name does not include a folder - use default
                default_folder = ProcessingConfig.getSetting(ProcessingConfig.OUTPUT_FOLDER)
                key = QDir(default_folder).filePath(key)

        if isinstance(self.parameter, QgsProcessingParameterFolderDestination):
            return key

        if isinstance(self.parameter, QgsProcessingParameterFileDestination):
            return key

        value = QgsProcessingOutputLayerDefinition(key)
        value.createOptions = {'fileEncoding': self.encoding}
        return value

    def getValue(self):
        key = None
        if self.use_temporary and isinstance(self.parameter, QgsProcessingParameterFeatureSink):
            key = 'memory:'
        else:
            key = self.leText.text()

        if not key and self.parameter.flags() & QgsProcessingParameterDefinition.FlagOptional:
            return None

        value = QgsProcessingOutputLayerDefinition(key)
        value.createOptions = {'fileEncoding': self.encoding}
        return value

    def getValue(self):
        key = None
        if self.use_temporary and isinstance(self.parameter, QgsProcessingParameterFeatureSink):
            key = 'memory:'
        elif self.use_temporary and not self.default_selection:
            key = self.parameter.generateTemporaryDestination()
        else:
            key = self.leText.text()

        if not key and self.parameter.flags() & QgsProcessingParameterDefinition.FlagOptional:
            return None

        if isinstance(self.parameter, QgsProcessingParameterFolderDestination):
            return key

        if isinstance(self.parameter, QgsProcessingParameterFileDestination):
            return key

        value = QgsProcessingOutputLayerDefinition(key)
        value.createOptions = {'fileEncoding': self.encoding}
        return value