Django passing object ID in hiddeninput by populating - django

Question

I have an form which allows a user to edit an object description.
How can I populate an object ID in a form's hidden input value.
What I done so far is I added an field called hidden_field in forms.py but it only show the hidden_field . How can I link the hidden_field with the object ID
models.py
class School(models.Model):
user = models.ForeignKey(User)
name = models.CharField(max_length=55)
description = models.CharField(max_length=300,blank=True)
forms.py
class SchoolDescriptionForm(forms.ModelForm):
description = forms.CharField(widget=forms.Textarea,max_length=300)
hidden_field = forms.CharField(widget=forms.HiddenInput())
class Meta:
model = School
fields = ()
views.py
def SchoolEditor(request,school_id):
school = School.objects.get(pk=school_id,user=request.user)
form = SchoolDescriptionForm(instance=school) # I want to populate the object ID
return render(request,'schooleditor.html',{'school':school,'form':form})
template
<form method="POST" enctype="multipart/form-data">
{% csrf_token %}
{{ form.as_p }}
<input type = "submit" value= "save" />
{{ form.field.as_hidden }}
</form>

Answer 1

Change hidden_field to id and tell Django to include the School's id.
class SchoolDescriptionForm(forms.ModelForm):
description = forms.CharField(widget=forms.Textarea,max_length=300)
id = forms.CharField(widget=forms.HiddenInput())
class Meta:
model = School
fields = ('id', 'name', 'description')
EDIT:
If you want to conserve hidden_field as name you should then add a custom init method:
def __init__(self, *args, **kwargs):
super(SchoolDescriptionForm, self).__init__(*args, **kwargs)
if self.instance:
self.fields['hidden_field'].initial = instance.id

Answer 2

Just pass the object id in the form initial:
def SchoolEditor(request,school_id):
initial = {}
school = School.objects.get(pk=school_id,user=request.user)
if school:
initial.update({'hidden_field': school.id})
form = SchoolDescriptionForm(instance=school, initial=initial) # I want to populate the object ID
return render(request,'schooleditor.html',{'school':school,'form':form})