Feat/price parameter

entities/migrations/0002_entity_price_cents.py

@@ -0,0 +1,18 @@
+# Generated by Django 6.0.1 on 2026-01-24 03:43
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('entities', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='entity',
+            name='price_cents',
+            field=models.IntegerField(default=0),
+        ),
+    ]

entities/migrations/0003_entity_unit_price.py

@@ -0,0 +1,41 @@
+from decimal import Decimal
+from django.db import migrations, models
+
+
+def forwards(apps, schema_editor):
+    Entity = apps.get_model('entities', 'Entity')
+    for obj in Entity.objects.all():
+        # convert existing price_cents (int) to unit_price Decimal
+        cents = getattr(obj, 'price_cents', None)
+        if cents is not None:
+            obj.unit_price = Decimal(cents) / Decimal('100')
+            obj.save(update_fields=['unit_price'])
+
+
+def backwards(apps, schema_editor):
+    Entity = apps.get_model('entities', 'Entity')
+    for obj in Entity.objects.all():
+        val = getattr(obj, 'unit_price', None)
+        if val is not None:
+            obj.price_cents = int((Decimal(val) * Decimal('100')).to_integral_value())
+            obj.save(update_fields=['price_cents'])
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('entities', '0002_entity_price_cents'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='entity',
+            name='unit_price',
+            field=models.DecimalField(decimal_places=4, default=Decimal('0.0000'), max_digits=12),
+        ),
+        migrations.RunPython(forwards, backwards),
+        migrations.RemoveField(
+            model_name='entity',
+            name='price_cents',
+        ),
+    ]

entities/models.py

@@ -1,10 +1,23 @@
 from django.db import models
+from decimal import Decimal, ROUND_DOWN
+
 
 class Entity(models.Model):
     type = models.CharField(max_length=100)
     name = models.CharField(max_length=255, blank=True, null=True)
     description = models.TextField(blank=True, null=True)
+    # store unit price as Decimal with 4 decimal places to preserve precision from measurements
+    unit_price = models.DecimalField(max_digits=12, decimal_places=4, default=Decimal('0.0000'))
     created_at = models.DateTimeField(auto_now_add=True)
 
     def __str__(self):
-        return f"{self.type}: {self.name or self.pk}"
+        return f"{self.type}: {self.name or self.pk}"
+
+    def unit_price_float(self) -> float:
+        """Return unit price as float for convenience (not used for storage)."""
+        return float(self.unit_price or Decimal('0'))
+
+    def price_cents_truncated(self) -> int:
+        """Return price in cents after truncating to 2 decimal places (no rounding)."""
+        val = (Decimal(self.unit_price or Decimal('0'))).quantize(Decimal('0.01'), rounding=ROUND_DOWN)
+        return int((val * 100).to_integral_value())

entities/schemas.py

@@ -1,11 +1,14 @@
 from pydantic import BaseModel, constr
 from typing import Optional
 from datetime import datetime
+from decimal import Decimal
 
 class EntityBase(BaseModel):
     type: constr(max_length=100)
     name: Optional[constr(max_length=255)] = None
     description: Optional[str] = None
+    # store and accept unit_price with Decimal precision; API accepts float/str and will be parsed
+    unit_price: Optional[Decimal] = None
 
     model_config = {"from_attributes": True}
 
@@ -16,9 +19,12 @@ class EntityUpdate(BaseModel):
     type: Optional[constr(max_length=100)] = None
     name: Optional[constr(max_length=255)] = None
     description: Optional[str] = None
+    unit_price: Optional[Decimal] = None
 
     model_config = {"from_attributes": True}
 
 class EntityOut(EntityBase):
     id: int
-    created_at: datetime
+    created_at: datetime
+    # unit_price returned as Decimal (serialized by Pydantic)
+    unit_price: Decimal

entities/services.py

@@ -1,6 +1,7 @@
 from typing import Dict, Any
 from django.db import transaction
 from .models import Entity
+from decimal import Decimal, InvalidOperation, ROUND_DOWN
 
 def list_entities(
     name: str = None,
@@ -35,11 +36,32 @@ def get_entity(entity_id: int) -> Entity:
     return Entity.objects.get(pk=entity_id)
 
 def create_entity(data: Dict[str, Any]) -> Entity:
+    # accept `unit_price` (e.g. 50.99) and store as Decimal with 4 decimal places
+    unit = data.pop('unit_price', None)
+    if unit is not None:
+        # accept both 50.99 and '50,99' by normalizing comma to dot
+        unit_str = str(unit).replace(',', '.')
+        try:
+            d = Decimal(unit_str)
+        except (InvalidOperation, ValueError):
+            d = Decimal(float(unit_str))
+        # store with 4 decimal places to preserve measurement precision, truncate (ROUND_DOWN)
+        data['unit_price'] = d.quantize(Decimal('0.0001'), rounding=ROUND_DOWN)
     with transaction.atomic():
         return Entity.objects.create(**data)
 
 def update_entity(entity_id: int, data: Dict[str, Any]) -> Entity:
     with transaction.atomic():
+        # support updating via `unit_price` as well
+        unit = data.pop('unit_price', None)
+        if unit is not None:
+            unit_str = str(unit).replace(',', '.')
+            try:
+                d = Decimal(unit_str)
+            except (InvalidOperation, ValueError):
+                d = Decimal(float(unit_str))
+            data['unit_price'] = d.quantize(Decimal('0.0001'), rounding=ROUND_DOWN)
+
         obj = Entity.objects.get(pk=entity_id)
         for k, v in data.items():
             setattr(obj, k, v)