在中間件中傳遞參數(shù)的方法取決于所使用的框架或環(huán)境，但通常通過工廠函數(shù)、選項(xiàng)類或直接在應(yīng)用時提供參數(shù)來實(shí)現(xiàn)。1. 在Express.js中，可以通過工廠函數(shù)返回中間件，并在應(yīng)用時傳遞參數(shù)，例如logAction('User visited page')；2. 在Laravel中，可在中間件類的handle方法中定義參數(shù)，并在路由中使用冒號傳遞值，如middleware('check-role:admin')；3. 在ASP.NET Core中，可通過選項(xiàng)類封裝配置，并在中間件構(gòu)造函數(shù)中注入該配置，再通過UseMiddleware方法傳入實(shí)例。此外，應(yīng)注意參數(shù)是靜態(tài)還是動態(tài)的，保持中間件解耦和可測試性，并妥善處理無效或缺失參數(shù)。

Passing parameters to middleware depends on the framework or environment you're using, but the general idea is to provide additional data or configuration when applying the middleware. Here's how to do it in a few common environments.

In Express.js (Node.js)

In Express, middleware functions can accept parameters beyond the standard req, res, and next. You can wrap your middleware in a factory function that takes parameters and returns the actual middleware function.

Example:

function logAction(message) {
  return function(req, res, next) {
    console.log(`Action: ${message}`);
    next();
  };
}

app.get('/route', logAction('User visited page'), (req, res) => {
  res.send('Hello World');
});

• The logAction function is a factory that returns the middleware.
• You pass the message parameter when applying the middleware.
• This lets you customize behavior per route or use case.

This pattern is especially useful for reusable logic like logging, authentication with roles, or rate limiting.

In Laravel (PHP)

Laravel allows passing parameters to middleware both when defining the middleware class and when applying it in routes.

Define middleware with parameters:

In your middleware class, the handle method can accept additional parameters:

public function handle($request, $next, $role) {
    if ($request->user()->hasRole($role)) {
        return $next($request);
    }

    return redirect('/home');
}

Register middleware with parameter in kernel:

'check-role' => \App\Http\Middleware\CheckRole::class,

Apply middleware with parameter in route:

Route::get('/admin', function () {
    //
})->middleware('check-role:admin');

• You define what parameters the middleware expects.
• You pass values when applying the middleware.
• It’s commonly used for role-based access control.

In ASP.NET Core (C#)

ASP.NET Core supports passing parameters to middleware via options classes or directly in the pipeline setup.

Using an options class:

Define an options class:

public class GreetingOptions {
    public string Message { get; set; }
}

Create middleware that uses the options:

public class GreetingMiddleware {
    private readonly RequestDelegate _next;
    private readonly GreetingOptions _options;

    public GreetingMiddleware(RequestDelegate next, IOptions<GreetingOptions> options) {
        _next = next;
        _options = options.Value;
    }

    public async Task Invoke(HttpContext context) {
        await context.Response.WriteAsync(_options.Message);
        await _next(context);
    }
}

Use it in Startup.cs:

app.UseMiddleware<GreetingMiddleware>(new GreetingOptions { Message = "Hello from middleware!" });

• You encapsulate configuration in a class.
• Middleware receives the configured object at runtime.
• This keeps your middleware clean and testable.

General Tips

• Always consider whether the parameter is static (known at startup) or dynamic (determined during request).
• Use wrapper functions or factories when you need to pass values dynamically.
• Avoid tightly coupling your middleware to specific business logic—keep it configurable.
• Make sure your middleware gracefully handles missing or invalid parameters.

基本上就這些。

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