try doing custom filter spec things to make unique routes stops filtered

chaloBEST/mumbai/admin.py

@@ -2,6 +2,22 @@ from django.contrib.gis import admin
 from django import forms
 from mumbai.models import *
 from django.contrib.contenttypes import generic
+from django.contrib.admin.filterspecs import FilterSpec, RelatedFilterSpec
+
+
+class CustomFilterSpec(RelatedFilterSpec):
+    def __init__(self, f, *args, **kwargs):
+        super(CustomFilterSpec, self).__init__(f, *args, **kwargs)
+        instance = f
+        stop_choices = instance.get_stop_choices()
+        CHOICES = (
+            (item.id, item.name) for item in stop_choices
+        )
+        self.lookup_choices = CHOICES
+
+ 
+FilterSpec.filter_specs.insert(0, (lambda f: bool(f.rel and hasattr(f, 'custom_filter_spec')), CustomFilterSpec))
+
 
 class RouteScheduleInline(admin.StackedInline):
     model = RouteSchedule

chaloBEST/mumbai/models.py

@@ -7,6 +7,8 @@ from django.db import connection
 import json
 from django.contrib.gis.measure import D
 
+
+
 STOP_CHOICES = ( ('U','Up'),
                  ('D', 'Down'),
                  )
@@ -301,7 +303,8 @@ class UniqueRoute(models.Model):
     to_stop = models.ForeignKey(Stop, related_name="unique_routes_to")
     distance = models.FloatField(blank=True, null=True)
     is_full = models.BooleanField()
-
+    from_stop.custom_filter_spec = True # this is used to identify the fields which use the custom filter
+    to_stop.custom_filter_spec = True # this is used to identify the fields which use the custom filter
     class Meta:
         verbose_name = 'Atlas'
         verbose_name_plural = 'Atlas'
@@ -310,7 +313,7 @@ class UniqueRoute(models.Model):
         return "%s: %s to %s" % (self.route.alias, self.from_stop_txt, self.to_stop_txt)
 
     def get_stop_choices(self):
-        return Stop.objects.filter(routedetail__route=self.instance.route).order_by('routedetail')
+        return Stop.objects.filter(routedetail__route=self.route).order_by('routedetail')
 
 class RouteSchedule(models.Model):
     unique_route = models.ForeignKey(UniqueRoute)