What middleware is used to publish php website?

As the name suggests, middleware refers to the interception and processing of request data, data verification, and logical processing to determine whether to allow entry to the next middleware between the request and the response.

Middleware is divided into prefix middleware and post-middleware; it can be used for permission authentication, logging, etc. (recommended learning: PHP Programming from Beginner to Master)

Middleware provides a convenient mechanism for filtering HTTP requests entering an application. For example, Laravel has a built-in middleware to verify user authentication. If the user does not pass identity authentication, the middleware will redirect the user to the login interface. However, if the user is authenticated, the middleware will allow the request further into the application.

Laravel automatically provides the VerifyCsrfToken middleware for all routing applications. When the HTTP Requst enters the application and passes through the VerifyCsrfToken middleware, the Token will be verified to prevent cross-site request forgery. The response will be added before the Http Response leaves the application. Appropriate Cookies. (Starting from laravel 5.5, CSRF middleware is only automatically applied to web routing)

Of course, in addition to identity authentication, other middleware can also be written to perform various tasks. For example: CORS middleware can be responsible for adding appropriate header information to all responses leaving the application; logging middleware can log all requests coming into the application.

Why do you need middleware?

1. Scenarios where middleware is not required

When we develop a relatively small outsourcing project, our first consideration is how to quickly complete the project And deliver it, rather than considering its future upgrades and expansions, and the business logic is not very complicated, then we can complete all business code with one controller (controller), which is no problem, but when we make a business logic it is more complicated What about the project?

2. Scenarios that require middleware

When the business logic is more complex, it is not appropriate to write all the business code in the controller, because the control The server will be very bloated and difficult to maintain. At this time, we need to layer the structure (service auxiliary controller, actions and Repositories auxiliary model, which I will mention in another article), and write cookie operations/user permission verification and other operations. into their respective middleware, so that the maintainability of the projects we write will be greatly improved.

Execution order of middleware?

1. Why does middleware have an execution sequence?

Assumption scenario: The user deletes a comment. We need to verify whether the user is logged in. After the comment is successfully deleted, it needs to be recorded. The operation log of this business.

Execution process (only the core process is considered): Entry (index.php) > Login verification (middleware 1) > Record data (middleware 2) > Business processing (controller) > Record Operation log (middleware 3) > Return response.

Why are there three middlewares instead of two middlewares above? The answer is that the recording of general operation logs cannot be completed by a middleware (you can try to think about how to implement a middleware). Let's look at the middleware corresponding to each operation separately.

Verify whether the user is logged in: middleware 1; record business operation log: middleware 2 middleware 3; if these three middlewares do not distinguish the order of execution, the requirement cannot be realized, which is why the middleware The files will be executed in order.

2. Pre-middleware & post-middleware

Here we will mention what pre-middleware and post-middleware are.

Pre-middleware: The middleware that is executed before the application processes the business request (controller), such as middleware 1 and middleware 2 in the above example.

Post-middleware: middleware that is executed after the application processes the business request (controller), corresponding to middleware 3.

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