Django and users entering data - django

Question

I am building a webapp which will be used by a company to carry out their daily operations. Things like sending invoices, tracking accounts receivable, tracking inventory (and therefore products). I have several models set up in my various apps to handle the different parts of the web-app. I will also be setting up permissions so that managers can edit more fields than, say, an office assistant.
This brings me to my question. How can I show all fields of a model and have some that can be edited and some that cannot be edited, and still save the model instance?
For example, I have a systems model for tracking systems (we install irrigation systems). The system ID is the primary key, and it is important for the user to see. However, they cannot change that ID since it would mess things up. Now, I have a view for displaying my models via a form using the "form.as_table". This is efficient, but merely spits out all the model fields with input fields filling in the values stored for that model instance. This includes the systemID field which should not be editable.
Because I don't want the user to edit the systemID field, I tried making it just a label within the html form, but django complains. Here's some code:
my model (not all of it, but some of it):
class System(models.Model):
systemID = models.CharField(max_length=10, primary_key=True, verbose_name = 'System ID')
systemOwner = models.ForeignKey (System_Owner)
installDate = models.DateField()
projectManager = models.ForeignKey(Employee, blank=True, null=True)
#more fields....
Then, my view for a specific model instance:
def system_details(request, systemID):
if request.method == 'POST':
sysEdit = System.objects.get(pk=systemID)
form = System_Form(request.POST, instance=sysEdit)
if form.is_valid():
form.save()
return HttpResponseRedirect('/systems/')
else:
sysView = System.objects.get(pk=systemID)
form = System_Form(instance=sysView)
return render_to_response('pages/systems/system_details.html', {'form': form}, context_instance=RequestContext(request))
Now the html page which displays the form:
<form action="" method="POST">
{% csrf_token %}
<table>
{{ form.as_table }}
</table>
<input type="submit" value="Save Changes">
<input type="button" value="Cancel Changes" onclick="window.location.href='/systems/'">
</form>
So, what I am thinking of doing is having two functions for the html. One is a form for displaying only those fields the user can edit, and the other is for just displaying the content of the field (the systemID). Then, in the view, when I want to save the changes the user made, I would do:
sysValues = System.objects.get(pk=SystemID)
form.save(commit = false)
form.pk = sysValues.sysValues.pk (or whatever the code is to assign the sysValues.pk to form.pk)
Is there an easier way to do this or would this be the best?
Thanks

Answer 1

One thing you can do is exclude the field you don't need in your form:
class System_Form(forms.ModelForm):
class Meta:
exclude = ('systemID',)
The other is to use read-only fields: http://docs.djangoproject.com/en/1.3/ref/contrib/admin/#django.contrib.admin.ModelAdmin.readonly_fields as #DTing suggessted

Answer 2

To make a field read only you can set the widget readonly attribute to True.
using your example:
class System_Form(ModelForm):
def __init__(self, *args, **kwargs):
super(System_Form, self).__init__(*args, **kwargs)
self.fields['systemID'].widget.attrs['readonly'] = True
class Meta:
model = System
or exclude the fields using exclude or fields in the class Meta of your form and display it in your template if desired like so:
forms.py
class System_Form(ModelForms):
class Meta:
model = System
exclude = ('systemID',)
views.py
def some_view(request, system_id):
system = System.objects.get(pk=system_id)
if request.method == 'POST':
form = System_Form(request.POST, instance=system)
if form.is_valid():
form.save()
return HttpResponse('Success')
else:
form = System_Form(instance=system)
context = { 'system':system,
'form':form, }
return render_to_response('some_template.html', context,
context_instance=RequestContext(request))
some_template.html
<p>make changes for {{ system }} with ID {{ system.systemID }}</p>
<form method='post'>
{{ form.as_p }}
<input type='submit' value='Submit'>
</form>