Learn CRUD with MVP pattern in C# and WinForms

Learn CRUD with MVP pattern in C# and WinForms

Table of Contents:

1. Introduction
2. Understanding the MVP Pattern
3. Implementing the Model
4. Implementing the View
5. Implementing the Presenter
6. Loading and Displaying Pet Data
7. Performing Searches
8. Adding and Editing Pets
9. Deleting Pets
10. Saving Changes
11. Conclusion

Introduction

In this tutorial, we will learn how to Create a CRUD (Create, Read, Update, Delete) application using the MVP (Model-View-Presenter) pattern. The application will revolve around a simple table of bets, where users can search for specific bets, add new bets, edit existing ones, and delete bets. We will also focus on implementing data validation to ensure that the user inputs are accurate and of the correct format. Additionally, we will explore the advantages and implementation of the MVP pattern in projects. By the end of this tutorial, You will have a clear understanding of how to Apply the MVP pattern and leverage its benefits in your own projects.

Understanding the MVP Pattern

The MVP pattern, or Model-View-Presenter pattern, is a software pattern that aims to separate the UI (User Interface) and mechanisms from the business logic of an application. It consists of three main components: the Model, the View, and the Presenter. The Model represents the domain objects, which encapsulate data and implement business logic. The View is responsible for displaying the content of the Model on the screen and interacting with user events. The Presenter acts as the mediator between the View and the Model, passing user input from the View to the Model and vice versa. It ensures clear separation of concerns and enables cleaner code organization.

Implementing the Model

Before diving into the implementation of the Model, let's take a moment to understand its role within the MVP pattern. The Model represents the domain objects of an application, encapsulating data and implementing business logic. In our case, the Model will be the Pet class, which will have fields for the pet's ID, name, Type, and color. We will also define the validation rules for the fields using data annotation attributes. These attributes allow us to specify constraints such as required fields, STRING length, and format. By implementing these validations, we ensure that the user inputs are accurate and meet the specified criteria.

Implementing the View

The View is responsible for displaying the content of the Model on the screen and interacting with user events. In our case, the View will be a Windows Form that allows users to search for pets, add new pets, edit existing pets, and delete pets. To implement the View, we will first define an interface that represents the behavior and properties of the View. This abstraction allows us to decouple the View from the Presenter and enables easier unit testing. We will then create a concrete implementation of the View, which is the Windows Form itself. Within the Form, we will design the UI elements and associate them with the corresponding events. These events will be raised when the user performs certain actions, such as clicking buttons or pressing keys.

Implementing the Presenter

The Presenter acts as the mediator between the View and the Model, handling the communication between the two components. It interprets user events raised by the View, updates the View with data from the Model, and updates the Model Based on user actions. To implement the Presenter, we will define an interface that represents the behavior and properties of the Presenter. This allows us to decouple the Presenter from the View and the Model, making it easier to test and maintain. In the Presenter, we will subscribe to the events raised by the View and implement the corresponding functionality. For example, when the user performs a search, we will invoke the search event, retrieve the search value from the View, perform the search operation using the Model, and update the View with the results.

Loading and Displaying Pet Data

To load and display pet data in the View, we need to retrieve the data from the Model and Bind it to the UI elements. We can achieve this by implementing a method in the Presenter that retrieves the list of all pets from the Model and sets it as the data source for a data binding source. This data binding source can then be connected to the data GRID view in the View, allowing it to display the pet data. Whenever the data binding changes, such as when a new pet is added or an existing pet is edited, the data grid view will automatically update to reflect the changes.

Performing Searches

Another important functionality of our CRUD application is the ability to perform searches. Users should be able to search for specific pets based on their ID, name, type, or color. To implement this functionality, we will need to define a method in the Presenter that handles the search operation. This method will retrieve the search value entered by the user from the View, pass it to the Model, perform the search operation using the repository's getByValue method, and update the View with the results. If the search value is empty, the method will retrieve the list of all pets instead. By implementing this functionality, users will be able to easily find the pets they are looking for.

Adding and Editing Pets

Our CRUD application should allow users to add new pets and edit existing ones. To implement this functionality, we need to create dedicated forms or user controls that allow users to enter the pet details. When the user clicks the add or edit button, the corresponding form or user control should be displayed, allowing the user to enter or edit the pet details. Once the user confirms the changes, the Presenter should handle the add or edit event raised by the View. It should retrieve the pet details from the View, validate them using the Model's validation rules, pass the data to the Model, and update the View accordingly. This way, users can easily add new pets or edit existing ones, ensuring data accuracy and consistency.

Deleting Pets

In addition to adding and editing pets, our CRUD application should also allow users to delete pets. When the user selects one or more pets and clicks the delete button, the Presenter should handle the delete event raised by the View. It should retrieve the selected pets from the View, pass them to the Model, and delete them from the database. After successful deletion, the Presenter should update the View to reflect the changes. By implementing this functionality, users can easily remove unwanted pets from the database, ensuring data cleanliness and organization.

Saving Changes

To ensure data integrity and persistence, our CRUD application should provide a mechanism for saving changes to the database. This includes adding new pets, editing existing pets, and deleting pets. When the user clicks the save changes button, the Presenter should handle the save changes event raised by the View. It should check if any changes have been made to the pet data in the View, validate the data using the Model's validation rules, pass the data to the Model, and update the database accordingly. After successful save, the Presenter should update the View to reflect the changes. By implementing this functionality, users can confidently make changes to the pet data, knowing that their changes are properly saved and stored.

Conclusion

In conclusion, the Model-View-Presenter (MVP) pattern provides a structured and organized approach to building CRUD applications. By separating the concerns of the Model, View, and Presenter, developers can achieve cleaner code, easier maintenance, and improved scalability. In this tutorial, we have covered the basics of implementing the MVP pattern, focusing on the Model, View, and Presenter components. We have also explored how to load and display data, perform searches, add and edit pets, delete pets, and save changes to the database. By following the steps outlined in this tutorial, you will gain a solid understanding of how to leverage the MVP pattern in your own projects and create robust CRUD applications.