Improve sorting

ram/metadata/models.py

@@ -3,6 +3,7 @@ from django.db import models
 from django.urls import reverse
 from django.conf import settings
 from django.dispatch.dispatcher import receiver
+from django.core.exceptions import ValidationError
 from django_countries.fields import CountryField
 
 from ram.models import Document
@@ -49,10 +50,11 @@ class Manufacturer(models.Model):
 
     def get_absolute_url(self):
         return reverse(
-            "filtered", kwargs={
+            "filtered",
+            kwargs={
                 "_filter": "manufacturer",
                 "search": self.slug,
-            }
+            },
         )
 
     def logo_thumbnail(self):
@@ -83,10 +85,11 @@ class Company(models.Model):
 
     def get_absolute_url(self):
         return reverse(
-            "filtered", kwargs={
+            "filtered",
+            kwargs={
                 "_filter": "company",
                 "search": self.slug,
-            }
+            },
         )
 
     def extended_name_pp(self):
@@ -115,7 +118,7 @@ class Decoder(models.Model):
     )
 
     class Meta(object):
-        ordering = ["manufacturer", "name"]
+        ordering = ["manufacturer__name", "name"]
 
     def __str__(self):
         return "{0} - {1}".format(self.manufacturer, self.name)
@@ -135,28 +138,49 @@ class DecoderDocument(Document):
         unique_together = ("decoder", "file")
 
 
+def calculate_ratio(ratio):
+    try:
+        num, den = ratio.split(":")
+        return int(num) / float(den) * 10000
+    except (ValueError, ZeroDivisionError):
+        raise ValidationError("Invalid ratio format")
+
+
 class Scale(models.Model):
     scale = models.CharField(max_length=32, unique=True)
     slug = models.CharField(max_length=32, unique=True, editable=False)
-    ratio = models.CharField(max_length=16, blank=True)
-    gauge = models.CharField(max_length=16, blank=True)
-    tracks = models.CharField(max_length=16, blank=True)
+    ratio = models.CharField(max_length=16, validators=[calculate_ratio])
+    ratio_int = models.SmallIntegerField(editable=False, default=0)
+    tracks = models.FloatField(
+        help_text="Distance between model tracks in mm",
+    )
+    gauge = models.CharField(
+        max_length=16,
+        blank=True,
+        help_text="Distance between real tracks. Please specify the unit (mm, in, ...)",  # noqa: E501
+    )
 
     class Meta:
-        ordering = ["scale"]
+        ordering = ["-ratio_int", "-tracks", "scale"]
 
     def get_absolute_url(self):
         return reverse(
-            "filtered", kwargs={
+            "filtered",
+            kwargs={
                 "_filter": "scale",
                 "search": self.slug,
-            }
+            },
         )
 
     def __str__(self):
         return str(self.scale)
 
 
+@receiver(models.signals.pre_save, sender=Scale)
+def scale_save(sender, instance, **kwargs):
+    instance.ratio_int = calculate_ratio(instance.ratio)
+
+
 class RollingStockType(models.Model):
     type = models.CharField(max_length=64)
     order = models.PositiveSmallIntegerField()
@@ -171,10 +195,11 @@ class RollingStockType(models.Model):
 
     def get_absolute_url(self):
         return reverse(
-            "filtered", kwargs={
+            "filtered",
+            kwargs={
                 "_filter": "type",
                 "search": self.slug,
-            }
+            },
         )
 
     def __str__(self):
@@ -193,10 +218,11 @@ class Tag(models.Model):
 
     def get_absolute_url(self):
         return reverse(
-            "filtered", kwargs={
+            "filtered",
+            kwargs={
                 "_filter": "tag",
                 "search": self.slug,
-            }
+            },
         )