PyQt5 StringSpinBox – Looping the strings

In this article we will see how we can make the string values repeat themselves when the last value reaches it should go back to the first value similarly when value is decremented after first value it should go back to the last value. In order to do this we have to change the custom class code of the StringSpinBox. Below is the code for the custom StringSpinBox class

# custom class for String Spin Box
class StringBox(QSpinBox):

    # constructor
    def __init__(self, parent=None):
        super(StringBox, self).__init__(parent)

        # list of strings
        strings = ["a", "b", "c", "d", "e", "f", "g"]


        # calling set Strings method with
        # adding blank value in front and in end
        self.setStrings(["BLANK"] + strings + ["BLANK"])

        # show first value from index 1
        self.setValue(1)

    def reset_spin(self):
        if self.value() == len(self.strings()) - 1:
            self.setValue(0)

    # method setString
    # similar to set value method
    def setStrings(self, strings):

        # making strings list
        strings = list(strings)

        # making tuple from the string list
        self._strings = tuple(strings)

        # creating a dictionary
        self._values = dict(zip(strings, range(len(strings))))

        # setting range to it the spin box
        self.setRange(0, len(strings)-1)

    # overwriting the textFromValue method
    def textFromValue(self, value):

        # returning string from index
        # _string = tuple
        return self._strings[value]

    # overwriting the stepBy method
    # method that get called when values get incremented or decremented
    def stepBy(self, step):

        # checking if current value is 1 and step is -1
        # step = -1 means decrement
        if self.value() == 1 and step == -1:

            # set current value to maximum
            self.setValue(self.maximum())

        # checking if current value is maximum -1 and step is 1
        # step = 1 means Increment
        elif self.value() == self.maximum() - 1 and step == 1:

            # setting current value to 0
            self.setValue(0)
        
        # calling stepBy method of QSpinBox
        QSpinBox.stepBy(self, step)

Explanation : Inside the String spin box custom class overwrite the stepBy method which get called when increment or decrement takes place there check that if there is decrement and current value is minimum then change its value to maximum similarly if there is increment and it is currently at maximum value then change its value to minimum -1 value. Below is the implementation 

Output :