Backbone.js - 替换集合中的现有模型

I have the following collection:

我有以下集合：

UsersMod.users_list = Backbone.Collection.extend({

    add : function(model) {

        var duplicate = this.any(function(_model) { 

            return _model.get('user') === model.get('user');

        });

        if (duplicate) {

            return false;

        }

        Backbone.Collection.prototype.add.call(this, model);

    }

});
Us