allow for sorting/filtering of JSON objects when using PostgreSQL #247

Author: dalenhughes

dynamic_rest/filters.py

@@ -3,10 +3,11 @@
 from django.core.exceptions import ValidationError as InternalValidationError
 from django.core.exceptions import ImproperlyConfigured
 from django.db.models import Q, Prefetch, Manager
+from django.db.models.expressions import RawSQL, OrderBy
 from django.utils import six
 from rest_framework import serializers
 from rest_framework.exceptions import ValidationError
-from rest_framework.fields import BooleanField, NullBooleanField
+from rest_framework.fields import BooleanField, NullBooleanField, JSONField
 from rest_framework.filters import BaseFilterBackend, OrderingFilter
 
 from dynamic_rest.utils import is_truthy
@@ -124,9 +125,18 @@ def generate_query_key(self, serializer):
 
             if i == last:
                 break
-
+            
             # Recurse into nested field
             s = getattr(field, 'serializer', None)
+            if isinstance(field, JSONField):
+                # If a json field is found, append any terms following
+                j = i+1
+                while j < len(self.field):            
+                    rewritten.append(self.field[j])
+                    j += 1
+                if self.operator:
+                    rewritten.append(self.operator)
+                return ('__'.join(rewritten), self.field)
             if isinstance(s, serializers.ListSerializer):
                 s = s.child
             if not s:
@@ -192,14 +202,12 @@ def filter_queryset(self, request, queryset, view):
         # after this is called may not behave as expected
         extra_filters = self.view.get_extra_filters(request)
 
-        disable_prefetches = self.view.is_update()
-
         self.DEBUG = settings.DEBUG
 
         return self._build_queryset(
             queryset=queryset,
             extra_filters=extra_filters,
-            disable_prefetches=disable_prefetches,
+	    disable_prefetches=False,
         )
 
     """
@@ -643,7 +651,12 @@ def filter_queryset(self, request, queryset, view):
         """
         self.ordering_param = view.SORT
 
-        ordering = self.get_ordering(request, queryset, view)
+        ordering, nested = self.get_ordering(request, queryset, view)
+        if ordering and nested:
+            ordering_str = ''.join(ordering)
+            if ordering_str.startswith('-'):
+                return queryset.order_by(OrderBy(RawSQL('LOWER(%s)'%(ordering_str[1:]), nested), descending=True))
+            return queryset.order_by(OrderBy(RawSQL('LOWER(%s)'%(ordering_str), nested), descending=False))
         if ordering:
             return queryset.order_by(*ordering)
 
@@ -656,9 +669,10 @@ def get_ordering(self, request, queryset, view):
         This method overwrites the DRF default so it can parse the array.
         """
         params = view.get_request_feature(view.SORT)
+        nested = []
         if params:
             fields = [param.strip() for param in params]
-            valid_ordering, invalid_ordering = self.remove_invalid_fields(
+            valid_ordering, invalid_ordering, nested = self.remove_invalid_fields(
                 queryset, fields, view
             )
 
@@ -669,10 +683,10 @@ def get_ordering(self, request, queryset, view):
                     "Invalid filter field: %s" % invalid_ordering
                 )
             else:
-                return valid_ordering
+                return valid_ordering, nested
 
         # No sorting was included
-        return self.get_default_ordering(view)
+        return self.get_default_ordering(view), nested
 
     def remove_invalid_fields(self, queryset, fields, view):
         """Remove invalid fields from an ordering.
@@ -690,14 +704,14 @@ def remove_invalid_fields(self, queryset, fields, view):
             stripped_term = term.lstrip('-')
             # add back the '-' add the end if necessary
             reverse_sort_term = '' if len(stripped_term) is len(term) else '-'
-            ordering = self.ordering_for(stripped_term, view)
+            ordering, nested = self.ordering_for(stripped_term, view)
 
             if ordering:
                 valid_orderings.append(reverse_sort_term + ordering)
             else:
                 invalid_orderings.append(term)
 
-        return valid_orderings, invalid_orderings
+        return valid_orderings, invalid_orderings, nested
 
     def ordering_for(self, term, view):
         """
@@ -707,7 +721,7 @@ def ordering_for(self, term, view):
         Raise ImproperlyConfigured if serializer_class not set on view
         """
         if not self._is_allowed_term(term, view):
-            return None
+            return None, None
 
         serializer = self._get_serializer_class(view)()
         serializer_chain = term.split('.')
@@ -716,10 +730,26 @@ def ordering_for(self, term, view):
 
         for segment in serializer_chain[:-1]:
             field = serializer.get_all_fields().get(segment)
+            
+            # If its a JSONField, construct a RawSQL command in the form of 'jsonField->{}'.format('nestedField')' or 'jsonField->{}->>{}'.format('nested','doubleNested')
+            if field and isinstance(field, JSONField):
+                json_chain_start = str(segment)
+                json_chain = ''
+                nested = []
+                first = True
+                for nterm in serializer_chain[1:]:
+                    if first:
+                        json_chain += '->>%s'
+                        first = False
+                    else:
+                        json_chain = '->%s'+json_chain
+                    nested.append(nterm)
+                json_chain = json_chain_start + json_chain
+                return json_chain, nested
 
             if not (field and field.source != '*' and
-                    isinstance(field, DynamicRelationField)):
-                return None
+                      isinstance(field, DynamicRelationField)):
+                return None, None
 
             model_chain.append(field.source or segment)
 
@@ -729,11 +759,11 @@ def ordering_for(self, term, view):
         last_field = serializer.get_all_fields().get(last_segment)
 
         if not last_field or last_field.source == '*':
-            return None
+            return None, None
 
         model_chain.append(last_field.source or last_segment)
 
-        return '__'.join(model_chain)
+        return '__'.join(model_chain), None
 
     def _is_allowed_term(self, term, view):
         valid_fields = getattr(view, 'ordering_fields', self.ordering_fields)