你确定 FirstName 和 LastName 是可观察对象?如果你不确定，试试这个:

You sure FirstName and LastName are observables? If you're not sure, try this:

optionsText: function(item) { return ko.unwrap(item.FirstName) + '-' + ko.unwrap(item.LastName); }

或者更好的是，在您的视图模型中创建一个计算:

Or better yet, create a computed in your viewmodel:

self.FullName = function() {
    return ko.unwrap(self.FirstName) + '-' + ko.unwrap(self.LastName);
};

还有:

optionsText: 'FullName'