> For the complete documentation index, see [llms.txt](https://neomatrixcode.gitbook.io/merly/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://neomatrixcode.gitbook.io/merly/guide/middleware.md).

# Middleware

It is possible to execute functions before or after the function associated with an endpoint, this in order to reprocess certain data or carry out previous validations.

It is possible to create a custom function that is executed before or after the function associated with an endpopint, the function will be created with the desired name and later it will be passed as a variable.

```julia
function authenticate(request, HTTP)
  isAuthenticated = false

  if (request.params["status"] === "authenticated")
    isAuthenticated = true
  end

  return request, HTTP, isAuthenticated
end
```

The execution of the middleware can only be achieved with the funcionm format, it cannot with the `@route` and `@page` macros. The following structure must be specified where myfunction is the function associated with the path `"/ verify /: status"`. In line number 13, the order in which the functions will be executed is indicated, first the **`middleware`** function and then the **`myfunction`** function.

```julia
Get("/verify/:status",

  (result(;middleware=authenticate) = (request, HTTP)-> begin

  myfunction = (request, HTTP, isAuthenticated)-> begin

      if (isAuthenticated == false )
          return  HTTP.Response(403,string("Unauthenticated. Please signup!"))
      end
          return  HTTP.Response(200,string("<b>verify !</b>"))
      end

  return myfunction(middleware(request,HTTP)...)

  end)()

)
```