Complete replacement of Thing types with tag system

boxes/models.py

@@ -1,7 +1,6 @@
 import os
 from django.db import models
 from django.utils.text import slugify
-from mptt.models import MPTTModel, TreeForeignKey
 
 
 def thing_picture_upload_path(instance, filename):
@@ -50,34 +49,64 @@ class Box(models.Model):
         return self.id
 
 
-class ThingType(MPTTModel):
-    """A hierarchical type/category for things stored in boxes."""
+class Facet(models.Model):
+    """A category of tags (e.g., Priority, Category, Status)."""
 
-    name = models.CharField(max_length=255)
-    parent = TreeForeignKey(
-        'self',
-        on_delete=models.CASCADE,
-        null=True,
-        blank=True,
-        related_name='children'
+    class Cardinality(models.TextChoices):
+        SINGLE = 'single', 'Single (0..1)'
+        MULTIPLE = 'multiple', 'Multiple (0..n)'
+
+    name = models.CharField(max_length=100, unique=True)
+    slug = models.SlugField(max_length=100, unique=True)
+    color = models.CharField(
+        max_length=7,
+        default='#667eea',
+        help_text='Hex color code (e.g., #667eea)'
+    )
+    cardinality = models.CharField(
+        max_length=10,
+        choices=Cardinality.choices,
+        default=Cardinality.MULTIPLE,
+        help_text='Can a thing have multiple tags of this facet?'
     )
 
-    class MPTTMeta:
-        order_insertion_by = ['name']
+    class Meta:
+        ordering = ['name']
 
     def __str__(self):
         return self.name
 
+    def save(self, *args, **kwargs):
+        if not self.slug:
+            self.slug = slugify(self.name)
+        super().save(*args, **kwargs)
+
+
+class Tag(models.Model):
+    """A tag value for a specific facet."""
+
+    facet = models.ForeignKey(
+        Facet,
+        on_delete=models.CASCADE,
+        related_name='tags'
+    )
+    name = models.CharField(
+        max_length=100,
+        help_text='Tag description (e.g., "High", "Electronics")'
+    )
+
+    class Meta:
+        ordering = ['facet', 'name']
+        unique_together = [['facet', 'name']]
+
+    def __str__(self):
+        return f'{self.facet.name}:{self.name}'
+
 
 class Thing(models.Model):
     """An item stored in a box."""
 
     name = models.CharField(max_length=255)
-    thing_type = models.ForeignKey(
-        ThingType,
-        on_delete=models.PROTECT,
-        related_name='things'
-    )
     box = models.ForeignKey(
         Box,
         on_delete=models.PROTECT,
@@ -85,6 +114,11 @@ class Thing(models.Model):
     )
     description = models.TextField(blank=True)
     picture = models.ImageField(upload_to=thing_picture_upload_path, blank=True)
+    tags = models.ManyToManyField(
+        Tag,
+        blank=True,
+        related_name='things'
+    )
 
     class Meta:
         ordering = ['name']