docs/reference/application/advanced-usage/sails.registerActionMiddleware.md
This feature is still experimental.
This method is still under development, and its interface and/or behavior could change at any time.
Register a new action middleware function that will be applied to actions with the specified identities.
sails.registerActionMiddleware(actionMiddlewareFns, actionIdentities);
Action middleware functions are essentially policies that you declare programmatically (rather than via sails.config.policies). In fact, policies are implemented under-the-hood using action middleware. The registerActionMiddleware() method is mainly useful in custom hooks as a way of adding new policies to an app.
| Argument | Type | Details | |
|---|---|---|---|
| 1 | actionMiddlewareFns | ((function)) or ((array)) | One or more middleware functions to register. Action middleware (like policies) must be functions which accept req, res and next arguments. |
| 2 | actionIdentities | ((string)) | An expression that indicates the action or actions that the action middleware should apply to. Use * at the end for a wildcard; e.g. user/* will apply to any actions whose identities begin with user/. Use a ! at the beginning to indicate that the action middleware should NOT apply to the actions specified by the expression, e.g. !user/foo or !user/*. Multiple identity expressions can be specified by separating with a comma, e.g. pets/count,user/*,!user/tickle |
The
actionIdentitiesargument expects the identities to be expressed as if they were standalone actions. To apply action middleware to actions inside of a controller file (e.g.UserController.js), simply refer to the lower-cased version of the filename without "Controller" (e.g.user).
As an example of action middleware that might be applied in a custom hook, imagine a page view counter (this code might be added to the initialize method of the hook):
// Declare a local var to hold the number of views for each URL.
var pageViews = {};
// Register middleware to record each page view.
sails.registerActionMiddleware(
// First argument is the middleware to run
function countPage (req, res, next) {
// Initialize the page counter to zero if this is the first time we've seen this URL.
pageViews[req.url] = pageViews[req.url] || 0;
// Increment the page counter.
pageViews[req.url]++;
// Add the current page count to the request, so that it can be used in other middleware / actions.
req.currentPageCount = pageViews[req.url];
// Continue to the next matching middleware / action
next();
},
// Second argument is the actions to apply the middleware to. In this case, we want the
// hook to apply to all actions EXCEPT the `show-page-views` action supplied by this hook.
'*, !page-view-hook/show-page-views'
);