I am building an ecommerce website for a project for my portfolio, and I wanted to know where the calculations should be done for the cart.

Normally I use react and I create a model folder, route folder and a controller folder but the way I was taught Angular it seems like the services acts like the routes and the actual calls to the database are done in the node server file which I am sure I could separate into a separate controller file. My question is where should the calculations for the cart be done before I send the order to the database? I thought about doing it in the cart component before the order is place or should it be done in the services or in the backend in the controller? I am just trying to figure out what is the standard

CodePudding user response：

I don't know the calculation you need exactly, but since it is an e-commerce website I assume it is simple math such as the total payment amount of checkout.

The main role of the server is communicating to the database. If a task does not involve interacting with data, you can do the calculations on the client-side. Leaving details on client-side allows you to have access to details of your formula, and reduce the communication time between client and server.

CodePudding user response：

When writing an Angular app, I think it is important to adhere to the following principles that:

Components - should have a single responsibility for simple view logic only, shouldn't reach out to the server, and shouldn't do complex calculations and/or logic that is not related to the view.

Services - should have a single responsibility for (reusable/shared) and complex logic, to do outbound communication and reach out to the server, and to act as data stores (using BehaviorSubjects).

Therefore, if your calculations are needed to update the view of the cart, I would vote that these calculations need to be made at the component. If your calculations are needed to update the items or the request to be sent to the server, they need to be made at the service.

Remember, the component "shouldn't know" how the data comes to it or how it is manipulated or sent to the server. The component should only know, given any data - how to present it in the view, and shouldn't "worry about" how that data came to it. Similarly, the component shouldn't know how the data is calculated before being sent to the server, and this would fall within the responsibility of the service that works with and processes the cart data and builds the request to the server.

However, you have to always consider the security of your app, and if a malicious data modification at the client side can affect your cart. If such caculations affect the app's security - they should at least be validated at the server if not fully delegated to it.