How can I run a “middleware” function before a rou

问题:

Say I have a backbone router like:

routes:
  ""                          : "homepage"
  "catalog/:id"               : "catalogPage"
  "catalog/:id/products/:id2" : "productPage"

homepage   :           -> doStuff()
catalogPage: (id)      -> doOtherStuff()
productPage: (id, id2) -> doEvenMoreStuff()

and a function:

executeBefore = -> console.log("hello")

If I want executeBefore to be called and executed each time a route is called and before the corresponding route method, is there a simple way to do it apart from inserting a call to executeBefore at the beginning of every route method ?

回答1:

You can override the route function in your router class to intercept the route calls :

var Router = Backbone.Router.extend({
    routes: {
        "" : "homepage",
        "catalog/:id" : "catalogPage"
    },

    route: function(route, name, callback) {
        var router = this;
        if (!callback) callback = this[name];

        var f = function() {
            console.log('route before', route);
            callback.apply(router, arguments);
            console.log('route after', route);
        };
        return Backbone.Router.prototype.route.call(this, route, name, f);
    },

    homepage: function() {
        console.log("homepage");
    },
    catalogPage: function(id) {
        console.log("catalogPage "+id);
    }
});

var r = new Router();
Backbone.history.start();

And a demo http://jsfiddle.net/nikoshr/EdLzh/

回答2:

Since Feb, 13, 2014, you can use router.execute(callback, args, name) (http://backbonejs.org/#Router-execute) for this.

So your interceptor will be looked something like this

routes: {
    '': 'homepage',
    'catalog/:id': 'catalogPage',
    'catalog/:id/products/:id2': 'productPage'
},
execute: function(callback, args, name) {
    // Do your stuff here
    executeBefore();

    if (callback) callback.apply(this, args);
}

https://github.com/jashkenas/backbone/commit/791033dc1aab53e9e5c9366f64a854224f851231

回答3:

you can also use backbone.routefilter plugin.

you'll be able to set a filter for all routes

var Router = Backbone.Router.extend({
  routes: {
    "": "index",
    "page/:id": "page"
  },
  before: function( route, params ) { ... },
  after: function( route, params ) { ... },
  index: function(){ ... },
  page: function( route ){ ... }
});

Or select some routes

var Router = Backbone.Router.extend({
  routes: {
    "": "index",
    "page/:id": "page"
  },
  before: {
    "": function( route ) { ... },
    "page/:id": function( route ) { ... }
  },
  after: function( route ) { ... },
  index: function(){ ... },
  page: function( route ){ ... }
});

回答4:

You can play with the Events :

Backbone.history.on('route', function () {
    // Do your stuff here.
    executeBefore();
});

visiting #help/uploading will fire a route:help event from the router.

Apparently, this would be triggered before the redirection :

https://github.com/documentcloud/backbone/blob/master/backbone.js#L1243

Backbone.history.route(route, function(fragment) {
    var args = router._extractParameters(route, fragment);
    callback && callback.apply(router, args);
    router.trigger.apply(router, ['route:' + name].concat(args));
    router.trigger('route', name, args);
    Backbone.history.trigger('route', router, name, args);
});