What is the difference between DTOs and ViewModels in DDD?
Câu trả lời
In the context of Domain-Driven Design (DDD), both Data Transfer Objects (DTOs) and View Models serve as means to transfer data across different layers or parts of an application, but they have distinct roles and characteristics.
Data Transfer Objects (DTOs)
DTOs are simple objects that are used to transfer data between the software's layers or between different systems. They are often used in the context of DDD to encapsulate and transfer data across boundaries, such as from the domain layer to the application layer or from the application layer to an external system. The primary purpose of a DTO is to reduce the number of calls between these layers or systems, especially when those calls are expensive, such as in distributed systems. DTOs are typically "dumb" objects, meaning they contain no business logic, only data fields. They are almost always trivially serializable, making them ideal for data exchange in scenarios like API responses or requests[1][3][5].
View Models
View Models, on the other hand, are specifically designed for use in the presentation layer of an application. They are tailored to the needs of a particular view or user interface, shaping data so that it can be easily displayed by the UI. Unlike DTOs, View Models can contain logic, particularly presentation logic, which helps in determining what data to display and how to display it. This logic might include formatting of data, deciding which fields to show or hide based on certain conditions, and basic validation to ensure the UI receives data in the expected format. The purpose of a View Model is to decouple the UI from the model's implementation details, allowing the UI to remain "dumb" and focused solely on presentation[1][3].
Key Differences
Purpose and Scope: DTOs are used for general data transfer across layers or systems, focusing on reducing the overhead of data exchange. View Models are specifically designed for the presentation layer, shaping data for display in the UI.
Logic: DTOs are typically devoid of logic, serving purely as data carriers. View Models can contain presentation logic to aid in displaying data in the UI.
