Create DateTime widget for QGIS Processing Tool

date_time_widget_example.py

from qgis.PyQt.QtCore import (
    QCoreApplication,
    QDateTime,
)

from processing.gui.wrappers import WidgetWrapper
from qgis.gui import QgsDateTimeEdit

from qgis.core import (
    Qgis,
    QgsMessageLog,
    QgsProcessingParameterString,
    QgsProcessingAlgorithm,
)

from PyQt5.QtCore import Qt


DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss"


class DateTimeWidget(WidgetWrapper):
    """ QDateTimeEdit widget with calendar pop up """

    def createWidget(self):
        
        self._combo = QgsDateTimeEdit()
        self._combo.setCalendarPopup(True)
        
        self._combo.setDisplayFormat(DATE_TIME_FORMAT)

        today = QDateTime.currentDateTime()
        self._combo.setDateTime(today)

        return self._combo

    def setValue(self, value):
        self._combo.setDateTime(value)

    def value(self):
        date_chosen = self._combo.dateTime()
        return date_chosen.toString(Qt.ISODate)


class DateTimeWidgetTest(QgsProcessingAlgorithm):
    
    DATE_SELECTION = "DATE_SELECTION"

    def __init__(self):
        super().__init__()

    def tr(self, string):
        return QCoreApplication.translate("Processing", string)

    def name(self):
        return "PrintDateTime"
    
    def displayName(self):
        return "Prints a datetime string"
    
    def group(self):
        return "Example Scripts"
    
    def groupId(self):
        return "playground"
        
    def createInstance(self):
        return type(self)()

    def initAlgorithm(self, config=None):
        
        param = QgsProcessingParameterString(
            self.DATE_SELECTION,
            self.tr("Date Selection"),
            defaultValue=QDateTime.currentDateTime().addDays(-31),
            optional=False
        )
        
        param.setMetadata({'widget_wrapper': {"class": DateTimeWidget}})
        
        self.addParameter(param)
    
    def processAlgorithm(self, parameters, context, feedback):

        datetime = self.parameterAsDateTime(parameters, self.DATE_SELECTION, context);
        
        QgsMessageLog.logMessage(str(datetime), level=Qgis.Info)
        
        return {}