delete(): don't allow None documents in list of IDs

Doesn't make sense to delete None documents, so make it an exception.
This means we need to filter the original list for not Nones.
Not sure an exception is the wanted behaviour here, but at the same time
I wanted to avoid the '<delete></delete>' command being sent over to Solr
(although that does NOT delete all documents).

Author: Cosimo Streppone

pysolr.py

@@ -825,12 +825,17 @@ def delete(self, id=None, q=None, commit=True, waitFlush=None, waitSearcher=None
         elif id is not None and q is not None:
             raise ValueError('You many only specify "id" OR "q", not both.')
         elif id is not None:
-            m = '<delete>'
             if type(id) not in (list, set):
                 id = [ id ]
-            for i in id:
-                m += '<id>%s</id>' % i
-            m += '</delete>'
+            else:
+                id = filter(lambda x: x is not None, id)
+            if len(id) > 0:
+                m = '<delete>'
+                for i in id:
+                    m += '<id>%s</id>' % i
+                m += '</delete>'
+            else:
+                raise ValueError('The list of documents to delete was empty.')
         elif q is not None:
             m = '<delete><query>%s</query></delete>' % q
 

tests/client.py

@@ -463,6 +463,10 @@ def test_delete(self):
         self.solr.delete(id=to_delete)
         self.assertEqual(len(self.solr.search('*:*')), 0)
 
+        # Can't delete when the list of documents is empty
+        self.assertRaises(ValueError, self.solr.delete, id=[None, None, None])
+        self.assertRaises(ValueError, self.solr.delete, id=[None])
+
         # Need at least one.
         self.assertRaises(ValueError, self.solr.delete)
         # Can't have both.