Dirty checking with shared service between controllers, One way works the other does not?

Question

While attempting to answer a question regarding sharing data between two separate controllers I ran into a question .

I usually use services for for this task and

Answer 1

When Angular sees

Does Not Work: {{badPerson.name}}

it sets up a $watch on object badPerson. Looking at your controller, $scope.badPerson is a reference to object DataService.badPerson. All is fine so far... the problem happens here:

setActivePersonDoesNotWork: function (person) {
    People.badPerson = person;
}

When this function executes, badPerson is assigned a new/different object reference, but the controller is still $watching the old/original object reference.

The fix is to use angular.copy() to update the existing badPerson object, rather than assigning a new reference:

setActivePersonDoesNotWork: function (person) {
    angular.copy(person, People.badPerson);
}

This also explains why setActivePersonWorks() works -- it does not assign a new object reference.