Lecture 3 revision

MVC – Controllers and Views

3-layer architecture

• The 3-Layer Architecture is a software design pattern that divides applications into three main categories or layers:
  • Presentation
  • Business Logic (or Application Layer)
  • Data Layer
• This architecture aims to separate the user interface, the business logic, and the data storage, which promotes a clean separation of concerns.

MVC + 3-layer architecture

• The MVC pattern is a specialized form of 3-layer architecture, making it highly relevant to modern web development practices

• separate out what we are building into three separate layers
• MVC allows us to use REST
  • REST - representation state controllers

Model–view–controller (MVC) - a software architectural pattern, that separates an application's data, user interface, and control flow into three components:

• Model:
  • Represents the data.
  • The model is often connected to a database and is responsible for retrieving and storing data.
• View:
  • Represents the user interface of an application,
  • is responsible for displaying data and getting user input.
  • HTML, CSS, and JavaScript.
• Controller:
  • Manages the flow of data between the model and the view,
  • is responsible for processing user input and directing the application’s behaviour.
  • includes code that implements business rules and other functionality.

• Model uses ORM a lot of the time
• model connects to the database is retrieves and stores the data

View

• HTML, CSS, javascript
• user interface of an application

Controller

• Flow of data between the model and the view
• business rules, processing

Benefits of MVC

• Simplifies Complex Applications:
  • By separating the application into three components, developers can focus on one aspect without affecting others.
• Facilitates Parallel Development:
  • Different developers can work on the Model, View, and Controller simultaneously.
• Easy to Modify or Scale:
  • Changes to the business logic or user interface can be made with minimal impact on the other components.
• Supports Reusability:
  • Components can be reused across different parts of the application or in different applications.

Convention vs Configuration

Convention vs. Configuration is a design philosophy that:

• impacts how software frameworks are structured (i.e. where files are located)
• how they expect developers to interact with them
• It's a trade-off between the ease of following predefined paths and files (convention) or the flexibility to define everything explicitly (configuration).
• Important advice:
  • Web frameworks (CodeIgniter, Django, Ruby on Rails, Flask, Next,JS) come with a predefined folder structure
  • Learn what the structure is and where files go
  • This will improve your productivity!

tools that you run from the command line that will do this for you

• CLI builds whole project scaffold for you

Why Choose CodeIgniter

• Simplicity and Efficiency:
  • Ideal for developers who need a straightforward and rapid development process without the bulkiness of larger frameworks.
• Flexibility:
  • Unlike some frameworks that enforce strict project environments, CodeIgniter provides the flexibility to organize files and structure the application as desired.
• Documentation & Support:
  • Excellent documentation and community support make it accessible for beginners and efficient for experienced developers.

Codeigniter Models

• The CodeIgniter's Model offers convenient features and additional functionality to make working with a single table in the database easier.
  • automatic database connection;
  • basic Create Read Update Delete methods;
  • in-model validation;
  • automatic pagination;
  • and more
• Models in CodeIgniter 4 are stored in the app/Models directory
• Use Spark to create a new model file e.g. php spark make:model Customers
• A new file called Customers.php is placed in app/Models
• To access models within your classes, you can create a new instance or use the model() helper function.

Raw SQL & QueryBuilder Class

• Builder can help you generate the raw SQL scripts, which will be sent to query().
• To load the Query Builder, use the table() method on the database connection.
• It's important to note that the Query Builder needs to be explicitly loaded if you require.
• Get Data(i.e. SELECT *): $builder->get()