Django Form If condition in view.py with 2 instance - django

Question

TO SAVE DATA that is inputted in form in Django i tried tomake it like this
I put this in my model.py
class Item(models.Model):
CATEGORY = (
('Gudang Kering', 'Gudang Kering'),
('Gudang Basah','Gudang Basah'),
)
name = models.CharField(max_length=200,null= True)
stock = models.IntegerField(default='0', blank=False, null=True)
category = models.CharField(max_length=200,null= True,choices=CATEGORY)
reorderlevel = models.IntegerField(default='0', blank=False, null=True)
maxreorderlevel = models.IntegerField(default='0', blank=False, null=True)
description = models.CharField(max_length=200,null= True, blank= True)
date_created = models.DateTimeField(auto_now_add= True)
tags = models.ManyToManyField(Tag)
def __str__(self):
return self.name
class Issue(models.Model):
STATUS = (
('Pending', 'Pending'),
('Granted','Granted'),
('Denied','Denied'),
)
customer = models.ForeignKey(Customer, null=True, on_delete= models.SET_NULL)
item = models.ForeignKey(Item, null=True, on_delete= models.SET_NULL)
quantity = models.IntegerField(default='0', blank=False, null=True)
date_created = models.DateTimeField(auto_now_add=True, auto_now=False)
status = models.CharField(max_length=200,null= True, choices=STATUS)
Then in view.py i define the form like this
def updateIssue(request, pk):
issue = Issue.objects.get(id=pk)
item = Item.objects.all()
form = UpdateIssueForm(instance=issue)
if request.method == 'POST':
form = UpdateIssueForm(request.POST,instance=issue)
#print ('printing:',request.POST)
if form.is_valid():
instance = form.save(commit=False)
if instance.status == 'Granted':
item.stock -= instance.quantity
instance.save()
item.save()
else:
instance.save()
return redirect('/')
context = {'form':form}
return render(request,'accounts/issue_form.html',context)``
The Goal
if instance == "Granted"
the item.stock will be decreased on the amount of instance.quantity
and will be saved.
else
instance will just be saved without affecting the stock from the 2nd model
The error
item = Item.objects.all()
even when called the item.stock have 0 attribute even when i have input data in database for that table

Answer 1

There is no need to get Item since we can access the Item related to Issue using the Issue object like issue.item. This is just an example from docs:
Article model has a field reporter which is a ForeignKey realted to Reporter model. Using Article object the Reporter object is accessed.
>>> new_article = r.article_set.create(headline="John's second story", pub_date=date(2005, 7, 29))
>>> new_article
<Article: John's second story>
>>> new_article.reporter
<Reporter: John Smith>
>>> new_article.reporter.id
1
Like so, we can access the Item using Issue
def updateIssue(request, pk):
issue = Issue.objects.get(id=pk) # we have our Issue here
form = UpdateIssueForm(instance=issue)
if request.method == 'POST':
form = UpdateIssueForm(request.POST,instance=issue)
if form.is_valid():
instance = form.save(commit=False)
if instance.status == 'Granted':
issue.item.stock -= instance.quantity # access Item by using Issue object's related field with name item
issue.item.save() # save the Item first
instance.save() # then the Issue
else:
instance.save()
return redirect('/')
context = {'form':form}
return render(request,'accounts/issue_form.html',context)