Python Could you help me fix my django forms code , I'm trying to get return_items based on the items_issued to a particular person

[yrenhke]

here are my models
class IssueItem(models.Model):
id = models.BigAutoField(primary_key=True)
person = models.ForeignKey(Person, on_delete=models.CASCADE)
grouped_item = models.ForeignKey(
GroupedItems,
on_delete=models.CASCADE,
related_name=‘issue_items’
)
units_issued = models.DecimalField(max_digits=7, decimal_places=2, default=0)
Date = models.DateField(default=timezone.now)


def save(self, *args, **kwargs):
self.grouped_item.calculate_totals()
super().save(*args, **kwargs)

class return_item(models.Model):
id = models.BigAutoField(primary_key=True)
person = models.ForeignKey(Person,
on_delete=models.CASCADE
)
grouped_item = models.ForeignKey(
GroupedItems,
on_delete=models.CASCADE,
related_name=‘returned_items’
)
units_returned = models.DecimalField(max_digits=7, decimal_places=2, default=0)
Date = models.DateField(default=timezone.now)


def save(self, *args, **kwargs):
self.grouped_item.calculate_total()
super().save(*args, **kwargs)

def str(self):
return self.Person

class GroupedItems(models.Model):
id = models.BigAutoField(primary_key=True)
grouped_item = models.CharField(max_length=30, unique=True)
total_units = models.DecimalField(max_digits=9, decimal_places=2, default=0)
total = models.PositiveIntegerField(default=0)
units_used = models.DecimalField(max_digits=8, decimal_places=2, default=0)
units_available = models.DecimalField(max_digits=8, decimal_places=2, default=0)
Units_returned = models.DecimalField(max_digits=8, decimal_places=2, default=0)


def calculate_total(self):

return_items = self.returned_items.all()
self.Units_returned = return_items.aggregate(units_returned=Sum('units_returned'))['units_returned'] or 0
self.units_used = self.units_used - self.Units_returned
def calculate_totals(self):
issue_items = self.issue_items.all()


self.units_used = issue_items.aggregate(units_issued=Sum('units_issued'))['units_issued'] or 0


self.units_used = self.units_used - self.Units_returned
self.units_available = self.total_units - self.units_used

def function(self):
sqlserverconn_aggregate = sqlserverconn.objects.filter(grouped_item=self).aggregate(
total_units=Sum('Units'),
total=Sum(F('Unit_cost') * F('Units'))
)
self.total_units = sqlserverconn_aggregate['total_units'] or 0
self.total = sqlserverconn_aggregate['total'] or 0


def str(self):
return f"{self.grouped_item}"

def save(self, *args, **kwargs):

super().save(*args, **kwargs)

class Meta:
indexes = [
models.Index(fields=['grouped_item', 'total_units'], name='grouped_item_total_units_idx'),
]

class Person(models.Model):
person = models.CharField(max_length=20)


def str(self):
return self.person

i have recievers to handle calculations don’t worry , where i am getting a problem is iin my forms specifically return_item form
class ReturnItemForm(forms.ModelForm):
person = forms.ModelChoiceField(
queryset=Person.objects.all(),
widget=forms.Select(attrs={‘class’: ‘form-control’}),
empty_label=None,
to_field_name=‘id’
)
Date = forms.DateField(
widget=forms.DateInput(attrs={‘class’: ‘form-control’, ‘type’: ‘date’}),
initial=timezone.now()
)
grouped_item = forms.ModelChoiceField(
queryset=IssueItem.objects.all().values_list(‘grouped_item__grouped_item’, flat=True).distinct(),
widget=forms.Select(attrs={‘id’: ‘id_grouped_item’}),
to_field_name=‘grouped_item’
)


class Meta:
model = return_item
fields = ['person', 'grouped_item', 'units_returned', 'Date']

def init(self, *args, **kwargs):
super(ReturnItemForm, self).init(*args, **kwargs)
if 'person' in self.data:

selected_person = self.data['person']

self.fields['grouped_item'].queryset = IssueItem.objects.filter(person=selected_person)

def clean_units_issued(self):
units_returned = self.cleaned_data.get('units_returned')
grouped_item = self.cleaned_data.get('grouped_item')

if units_returned > grouped_item.units_issued:
raise forms.ValidationError('units_returned', 'Units returned cannot exceed units issued.')

return units_returned

it when i input a person and the grouped items i get this error

ValueError at /return_item/​

Cannot assign “<IssueItem: IssueItem object (3)>”: “return_item.grouped_item” must be a “GroupedItems” instance.
i just want it to know that the item that is being selected was from a specific user if there is a way you can help me thanks

 

[phenomenon]

It seems like the issue is in the way you're populating the grouped_item field in your ReturnItemForm. The field is expecting a GroupedItems instance, but you are currently providing a queryset of IssueItem instances.

To fix this, you should modify the ReturnItemForm to properly filter the available grouped items based on the selected person. Here's a modified version of your ReturnItemForm:

from django import forms
from .models import return_item, Person, IssueItem

class ReturnItemForm(forms.ModelForm):
    person = forms.ModelChoiceField(
        queryset=Person.objects.all(),
        widget=forms.Select(attrs={'class': 'form-control'}),
        empty_label=None,
        to_field_name='id'
    )
    
    Date = forms.DateField(
        widget=forms.DateInput(attrs={'class': 'form-control', 'type': 'date'}),
        initial=timezone.now()
    )
    
    grouped_item = forms.ModelChoiceField(
        queryset=GroupedItems.objects.all(),
        widget=forms.Select(attrs={'id': 'id_grouped_item'}),
        to_field_name='grouped_item'
    )

    class Meta:
        model = return_item
        fields = ['person', 'grouped_item', 'units_returned', 'Date']

    def __init__(self, *args, **kwargs):
        super(ReturnItemForm, self).__init__(*args, **kwargs)
        if 'person' in self.data:
            selected_person = self.data['person']
            self.fields['grouped_item'].queryset = IssueItem.objects.filter(person=selected_person).values_list('grouped_item', flat=True).distinct()

    def clean_units_returned(self):
        units_returned = self.cleaned_data.get('units_returned')
        grouped_item = self.cleaned_data.get('grouped_item')

        if units_returned > grouped_item.units_issued:
            raise forms.ValidationError('Units returned cannot exceed units issued.')

        return units_returned

In this modified version:

1. The grouped_item field queryset is set to GroupedItems.objects.all() to allow the user to choose from all available grouped items.
2. In the init method, the queryset for grouped_item is filtered based on the selected person.

Make sure that you have imported GroupedItems at the beginning of your forms.py file:

from .models import return_item, Person, IssueItem, GroupedItems

This should resolve the error you're encountering.


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