added net weight, user, date etc. generates new document number with year as a prefix, restarts numbering every year

backend/api/migrations/0003_documentcounter.py

@@ -0,0 +1,29 @@
+# Generated by Django 4.2.8 on 2026-02-22 10:11
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("api", "0002_add_report_model"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="DocumentCounter",
+            fields=[
+                (
+                    "id",
+                    models.BigAutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("year", models.IntegerField(unique=True)),
+                ("last_number", models.IntegerField(default=0)),
+            ],
+        ),
+    ]

backend/api/models.py

@@ -1,4 +1,4 @@
-from django.db import models
+from django.db import models, transaction
 from django.contrib.auth.models import AbstractUser
 from django.utils import timezone
 
@@ -57,3 +57,18 @@ class Report(models.Model):
 
     def __str__(self):
         return self.name
+
+
+class DocumentCounter(models.Model):
+    year = models.IntegerField(unique=True)
+    last_number = models.IntegerField(default=0)
+
+
+def generate_doc_number(year):
+    with transaction.atomic():
+        counter, _ = DocumentCounter.objects.select_for_update().get_or_create(
+            year=year, defaults={'last_number': 0}
+        )
+        counter.last_number += 1
+        counter.save()
+        return f"{year}-{counter.last_number:06d}"

backend/api/serializers.py

@@ -125,14 +125,19 @@ class VehicleSerializer(serializers.ModelSerializer):
     extra = VehicleExtraSerializer(required=False, allow_null=True)
     tare_user_name = serializers.CharField(source='tare_user.username', read_only=True, default=None)
     gross_user_name = serializers.CharField(source='gross_user.username', read_only=True, default=None)
+    net_user_name = serializers.CharField(source='net_user.username', read_only=True, default=None)
 
     class Meta:
         model = Vehicle
         fields = ['id', 'vehicle_number', 'trailer1_number', 'trailer2_number', 'driver_pid',
                   'tare', 'tare_date', 'tare_user', 'tare_user_name',
-                  'gross', 'gross_date', 'gross_user', 'gross_user_name', 'extra']
+                  'gross', 'gross_date', 'gross_user', 'gross_user_name',
+                  'net', 'net_date', 'net_user', 'net_user_name',
+                  'doc_number', 'extra']
         read_only_fields = ['id', 'tare_date', 'tare_user', 'tare_user_name',
-                            'gross_date', 'gross_user', 'gross_user_name']
+                            'gross_date', 'gross_user', 'gross_user_name',
+                            'net', 'net_date', 'net_user', 'net_user_name',
+                            'doc_number']
 
     def create(self, validated_data):
         extra_data = validated_data.pop('extra', None)

backend/api/views.py

@@ -2,7 +2,7 @@ from rest_framework import viewsets, status
 from rest_framework.decorators import action
 from rest_framework.response import Response
 from rest_framework.permissions import IsAuthenticated, AllowAny
-from .models import ComPortReading, User, Report
+from .models import ComPortReading, User, Report, generate_doc_number
 from .serializers import (
     ComPortReadingSerializer, UserSerializer, UserDetailSerializer,
     ChangePasswordSerializer, VehicleSerializer, NomenclatureSerializer,
@@ -111,6 +111,16 @@ class ComPortReadingViewSet(viewsets.ModelViewSet):
         serializer.save(source_ip=self.get_client_ip(self.request))
 
 
+def _maybe_finalize(vehicle, user):
+    """If both tare and gross are set and net hasn't been calculated yet, compute net and assign doc_number."""
+    if vehicle.tare is not None and vehicle.gross is not None and vehicle.net is None:
+        vehicle.net = vehicle.gross - vehicle.tare
+        vehicle.net_date = timezone.now()
+        vehicle.net_user = user
+        vehicle.doc_number = generate_doc_number(timezone.now().year)
+        vehicle.save()
+
+
 class VehicleViewSet(viewsets.ModelViewSet):
     """
     API endpoint for vehicle management.
@@ -183,6 +193,7 @@ class VehicleViewSet(viewsets.ModelViewSet):
         vehicle.tare_date = timezone.now()
         vehicle.tare_user = request.user
         vehicle.save()
+        _maybe_finalize(vehicle, request.user)
 
         serializer = self.get_serializer(vehicle)
         sse_broadcast_update('vehicle', 'updated', serializer.data)
@@ -204,6 +215,7 @@ class VehicleViewSet(viewsets.ModelViewSet):
         vehicle.gross_date = timezone.now()
         vehicle.gross_user = request.user
         vehicle.save()
+        _maybe_finalize(vehicle, request.user)
 
         serializer = self.get_serializer(vehicle)
         sse_broadcast_update('vehicle', 'updated', serializer.data)