Filters and Sessions

Filters

Filters can be run before or after requests and can read the request, can read and modify the response, and even stop processing of a request (using halt).

Before-filters are evaluated before each request. Here’s an example:

before((request, response) -> {
    boolean authenticated;
    // ... check if authenticated
    if (!authenticated) {
       halt(401, "You are not welcome here");
    }
});

Filters optionally take a pattern, causing them to be evaluated only if the request path matches that pattern:

before("/protected/*", (request, response) -> {
     // if !authenticated
     halt(401, "Go Away!");
});

After-filters are evaluated after each request. Here’s an example:

...