Exploring Kivymd’s MVC Architecture: A Comprehensive Guide to Base Template Code | Part 3 | Novfensec Inc.

In this tutorial, we will look at how to implement the Model-View-Controller (MVC) architecture in Kivymd. MVC is a design pattern that separates an application into three main components: Model, View, and Controller. This allows for better organization and separation of concerns in your code.

Before we get started with the implementation, make sure you have Kivymd installed on your system. If you haven’t already, you can install Kivymd by running the following command in your terminal:

pip install kivymd

Now, let’s dive into implementing MVC in Kivymd.

Step 1: Setting Up the Base Template Code

First, let’s set up a basic Kivymd application with a simple UI layout. Create a new Python file, let’s call it main.py, and enter the following code:

from kivy.lang import Builder
from kivymd.app import MDApp

kv = '''
BoxLayout:
    orientation: 'vertical'

    MDToolbar:
        title: 'MVC Architecture in Kivymd'
        left_action_items: [['menu', lambda x: print('Menu')]]

    MDLabel:
        text: 'Hello, World!'
'''

class MainApp(MDApp):
    def build(self):
        return Builder.load_string(kv)

if __name__ == '__main__':
    MainApp().run()

In this code, we have a simple KivyMD application with a BoxLayout as the root layout, a MDToolbar at the top with a menu button, and a MDLabel displaying "Hello, World!".

Step 2: Implementing MVC Architecture

Now, let’s implement the MVC architecture in our Kivymd application. We will create separate files for the Model, View, and Controller classes.

Model

Create a new Python file called model.py and add the following code:

class Model:
    def __init__(self):
        self.message = 'Hello, World!'

    def get_message(self):
        return self.message

    def set_message(self, new_message):
        self.message = new_message

In the Model class, we have a message attribute with getter and setter methods to get and set the message.

View

Create a new Python file called view.py and add the following code:

from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label

class View(BoxLayout):
    def __init__(self, controller):
        super(View, self).__init__()
        self.orientation = 'vertical'

        self.label = Label(text=controller.get_message())
        self.add_widget(self.label)

In the View class, we have a View class that extends BoxLayout and displays a label with the message from the controller.

Controller

Create a new Python file called controller.py and add the following code:

from model import Model
from view import View

class Controller:
    def __init__(self):
        self.model = Model()
        self.view = View(self)

    def get_message(self):
        return self.model.get_message()

    def set_message(self, new_message):
        self.model.set_message(new_message)
        self.view.label.text = new_message

In the Controller class, we have a Controller class that initializes the model and view instances, and provides methods to get and set the message.

Step 3: Updating the Main App Code

Finally, update the main.py file to use the Model, View, and Controller classes:

from kivy.lang import Builder
from kivymd.app import MDApp

from controller import Controller

kv = '''
<Controller>:
    orientation: 'vertical'

    MDToolbar:
        title: 'MVC Architecture in Kivymd'
        left_action_items: [['menu', lambda x: print('Menu')]]

    MDLabel:
        id: message_label
        text: 'Hello, World!'
'''

class MainApp(MDApp):
    def build(self):
        controller = Controller()
        return Builder.load_string(kv)

if __name__ == '__main__':
    MainApp().run()

In this updated code, we import the Controller class and create an instance of it in the build method. We also update the kv string to use the Controller class as the root layout and set the label’s text to the message from the controller.

Conclusion

In this tutorial, we have looked at how to implement the MVC architecture in Kivymd. By separating the Model, View, and Controller components, we can achieve better code organization and maintainability in our applications. We have also walked through setting up the base template code for a Kivymd application and creating the Model, View, and Controller classes. Feel free to expand on this implementation and add more functionality to your Kivymd application.

Thank you for following along with this tutorial from Novfensec Inc. Happy coding!