facts: refactor random_fact onto FactCategory

since the views will have a FactCategory, not a Fact, we'll move the
convenience random_fact() there and use it in the FactManager

bss/dr.botzo#15

facts/models.py

@@ -23,18 +23,9 @@ class FactCategory(models.Model):
         """String representation."""
         return "{0:s}".format(self.name)
 
-
-class FactManager(models.Manager):
-    """Queries against Fact."""
-
-    def random_fact(self, category, regex=None):
-        """Get a random fact from the database."""
-        try:
-            fact_category = FactCategory.objects.get(name=category)
-        except FactCategory.DoesNotExist:
-            return None
-
-        facts = Fact.objects.filter(category=fact_category)
+    def random_fact(self, regex=None):
+        """Get a random fact in this category."""
+        facts = self.fact_set.all()
         if regex:
             facts = facts.filter(fact__iregex=regex)
 
@@ -44,6 +35,19 @@ class FactManager(models.Manager):
             return None
 
 
+class FactManager(models.Manager):
+    """Queries against Fact."""
+
+    def random_fact(self, category, regex=None):
+        """Get a random fact from the database."""
+        try:
+            factcategory = FactCategory.objects.get(name=category)
+        except FactCategory.DoesNotExist:
+            return None
+
+        return factcategory.random_fact(regex)
+
+
 class Fact(models.Model):
     """Define facts."""