Add queryset also method - like only but additive

parasolr/query/queryset.py

@@ -347,7 +347,7 @@ def query(self, **kwargs) -> 'SolrQuerySet':
         qs_copy.get_results(**kwargs)
         return qs_copy
 
-    def only(self, *args, **kwargs) -> 'SolrQuerySet':
+    def only(self, *args, replace=True, **kwargs) -> 'SolrQuerySet':
         """Use field limit option to return only the specified fields.
         Optionally provide aliases for them in the return. Subsequent
         calls will *replace* any previous field limits. Example::
@@ -358,12 +358,25 @@ def only(self, *args, **kwargs) -> 'SolrQuerySet':
         """
         qs_copy = self._clone()
         # *replace* any existing field list with the current values
-        qs_copy.field_list = list(args)
+        if replace:
+            qs_copy.field_list = list(args)
+        # unless specified, in which case append
+        else:
+            qs_copy.field_list.extend(list(args))
+
         for key, value in kwargs.items():
             qs_copy.field_list.append('%s:%s' % (key, value))
 
         return qs_copy
 
+    def also(self, *args, **kwargs) -> 'SolrQuerySet':
+        """Use field limit option to return the specified fields,
+        optionally provide aliases for them in the return. Works
+        exactly the same way as :meth:`only` except that it
+        does not any previously specified field limits.
+        """
+        return self.only(*args, replace=False, **kwargs)
+
     def highlight(self, field: str, **kwargs) -> 'SolrQuerySet':
         """"Configure highlighting. Takes arbitrary Solr highlight
         parameters and adds the `hl.` prefix to them.  Example use::

parasolr/query/tests/test_queryset.py

@@ -327,6 +327,30 @@ def test_only(self):
         fields_sqs = sqs.only(title='title_i')
         assert 'title:title_i' in fields_sqs.field_list
 
+    def test_also(self):
+        mocksolr = Mock(spec=SolrClient)
+        sqs = SolrQuerySet(mocksolr)
+        also_fields = ['title', 'author', 'date']
+        # field names, single list
+        fields_sqs = sqs.also(*also_fields)
+        # field list refined
+        assert fields_sqs.field_list == also_fields
+        # original field list unchanged
+        assert not sqs.field_list
+
+        # chaining is equivalent, since it adds
+        fields_sqs = sqs.also('title').also('author').also('date')
+        # field list refined
+        assert fields_sqs.field_list == also_fields
+        # original field list unchanged
+        assert not sqs.field_list
+
+        # with field alias
+        fields_sqs = fields_sqs.also(title='title_i')
+        # still includes previous
+        assert 'author' in fields_sqs.field_list
+        assert 'title:title_i' in fields_sqs.field_list
+
     def test_highlight(self):
         mocksolr = Mock(spec=SolrClient)
         sqs = SolrQuerySet(mocksolr)