Display full names in Form ChoiceField but saving ID's - django

Question

I have model Person - from another database
I copied all person_id to custom_id.
models.py
class Employee(models.Model):
custom_id = models.CharField(max_length=20, unique=True)
#property
def person(self):
return Person.objects.get(person_id='%s' % self.custom_id)
def __str__(self):
return '%s' % self.custom_id
class Task(models.Model):
employee = models.ManyToManyField(Employee, blank=True, null=True)
task = models.CharField(max_length=100)
comment = models.CharField(max_length=200)
def __str__(self):
return '%s' % self.task
I add my method person() to Employee which allow me to access other objects model in another database:
So basically when I type this in shell:
Employee.objects.get(custom_id='123').person.full_name
u'Adam Dylan'
I have a ModelForm which use ModelMultipleChoiceField
forms.py
class TaskCreateForm(forms.ModelForm):
employee = forms.ModelMultipleChoiceField(queryset=Employee.objects.all())
class Meta:
model = Task
But Employee.objects.all() returns bunch of custom_id's.
What I want is to show in form "Employee(..).person.full_name" but saving only custom_id's.

Answer 1

I am not sure why you think the answer I gave to your other question does not work here. Did you try the following? If it does not work, how exactly does it fail?
class EmployeeMultipleChoiceField(ModelMultipleChoiceField):
def label_from_instance(self, obj):
return obj.person.full_name
class TaskCreateForm(forms.ModelForm):
employee = EmployeeMultipleChoiceField(queryset=Employee.objects.all())
class Meta:
model = Task