How Should the Model Be Structured in an MVC Framework?

How Model Should Be Structured in MVC

In the Model-View-Controller (MVC) framework, the model component often raises questions about its appropriate structure and responsibilities. To address these concerns, let's explore the nature and purpose of a model in MVC.

What a Model Is Not

• Not a class or single object: The model is not a specific class or object. It represents a layer consisting of various structures.
• Not an ORM or database abstraction: The model is not simply an object-relational mapping (ORM) or database abstraction layer.

What a Model Is

In MVC, the model layer comprises three primary structures:

• Domain Objects: Logical containers of domain-specific information, encapsulating business logic and rules.
• Data Mappers: Responsible for managing data storage and retrieval, such as interacting with a database.
• Services: Facilitate communication between domain objects and data mappers, providing a higher-level interface to the business logic.

Interacting with a Model

To utilize the model layer, user interface (UI) components (views and controllers) can leverage dependency injection techniques to access the necessary services.

Altering the Model's State

Controllers serve as intermediaries, receiving user input and initiating changes to the model's state through service methods.

Presenting the Model's State

Views are responsible for displaying the current state of the model to the user.

Building the Model

Instead of focusing on creating a monolithic "Model" class, MVC requires the construction of services, domain objects, and data mappers.

Additional Observations

• Database tables and the model: Model structures do not necessarily correspond directly to database tables.
• Views and templates: Views handle presentational logic, not merely displaying templates.
• Relation between views and controllers: MVC implies a 1:1 relationship between views and controllers, each pair managing a specific page or functionality.

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