# Middleware

Middleware are pieces of code that are executed every time a request is made to the app. It is used to do pre-validations and, in our case, add global values ​​as props to each frontend render. The audit middleware is:

## **AuditUrlMiddleware**

Captures the urls visited by the user and values necessary to record the urls log, according to the defined strategy.

```shell
    class AuditUrlMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response
        # One-time configuration and initialization.

    def __call__(self, request):
        response = self.get_response(request)
        route = resolve(request.path).route
        if request.user.is_authenticated:
            user = request.user
        else:
            user = None

        path = request.path
        method = request.method
        try:
            params = request.body.decode("utf-8")
        except RawPostDataException:
            params = ""

        user_agent = get_device(request)
        ip = get_ip(request)
        strategy = models.AuditSettings.load().urls_log_strategy
        if strategy == models.AuditSettings.EVERYTHING:
            models.AuditUrlLog.create_url_log(
                path, method, params, user_agent, ip, user
            )

        elif strategy == models.AuditSettings.ONLY_WHITELIST:
            if bool(models.UrlListLog.objects.filter(path=route, is_active=True)):
                models.AuditUrlLog.create_url_log(
                    path, method, params, user_agent, ip, user
                )

        elif strategy == models.AuditSettings.EXCEPT_WHITELIST:
            if not bool(models.UrlListLog.objects.filter(path=route, is_active=True)):
                models.AuditUrlLog.create_url_log(
                    path, method, params, user_agent, ip, user
                )

        return response
```