feat: backoffice setup

backoffice/forms.py

@@ -0,0 +1,35 @@
+from django import forms
+from django.core.exceptions import ValidationError
+
+from shop.models import ProductVariant
+
+
+class ProductVariantForm(forms.ModelForm):
+    class Meta:
+        model = ProductVariant
+        fields = ('sku', 'stock', 'attribute_values')
+        widgets = {'attribute_values': forms.CheckboxSelectMultiple}
+
+    def __init__(self, *args, product=None, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.product = product or self.instance.product
+
+    def clean(self):
+        cleaned_data = super().clean()
+        attribute_values = cleaned_data.get('attribute_values')
+
+        if attribute_values is not None:
+            combination = set(attribute_values.values_list('pk', flat=True))
+            siblings = ProductVariant.objects.filter(product=self.product).exclude(pk=self.instance.pk)
+
+            for sibling in siblings:
+                if set(sibling.attribute_values.values_list('pk', flat=True)) == combination:
+                    raise ValidationError(
+                        'Ya existe una variante de este producto con la misma combinación de atributos.'
+                    )
+
+        return cleaned_data
+
+    def save(self, commit=True):
+        self.instance.product = self.product
+        return super().save(commit=commit)