Add item size property to disallow "add" action if container is full

inventory/migrations/0003_item_size.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.4 on 2020-12-22 00:34
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('inventory', '0002_base_data'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='item',
+            name='size',
+            field=models.PositiveIntegerField(default=1),
+        ),
+    ]

inventory/models/item.py

@@ -7,6 +7,7 @@ from .container import CanBeContained
 class Item(CanBeContained):
     name = models.TextField(max_length=255)
     description = models.CharField(max_length=4096)
+    size = models.PositiveIntegerField(default=1, help_text="Number of sub-compartments this item takes up")
     created_at = models.DateTimeField(auto_now_add=True)
     changed_at = models.DateTimeField(auto_now=True)
 

inventory/views/box.py

@@ -1,4 +1,4 @@
-from typing import cast, Union
+from typing import cast, Union, List, Any
 from django.contrib.auth.decorators import login_required
 from django.utils.decorators import method_decorator
 from django.views.generic import ListView, DetailView
@@ -30,16 +30,22 @@ class BoxView(DetailView):
                 idx = new_idx
             else:
                 instances = obj.filter(index=idx)
-                if instances.count() == 1:
-                    result.append(instances.first())
-                elif instances.count() > 1:
-                    sub = list(instances)
-                    result.append(sub)
-                else:
-                    result.append({
+                items: List[dict[str, Any]] = []
+
+                # Add all items to the layout container
+                if instances.count() > 0:
+                    items.extend(list(instances))
+
+                # Append "Add one more entry" if we do not exceed the maximum number
+                # of items yet
+                size = sum([item.size for item in items])
+                if size < sublayout:
+                    items.append({
                         "index": idx,
                         "container_id": self.object.pk
                     })
+
+                result.append(items)
                 idx += 1
         return result, idx