Added support for slicing multiple times in Search class

Fixes elastic#799

Author: miguelgrinberg

elasticsearch_dsl/search_base.py

@@ -352,20 +352,27 @@ def __getitem__(self, n):
             # If negative slicing, abort.
             if n.start and n.start < 0 or n.stop and n.stop < 0:
                 raise ValueError("Search does not support negative slicing.")
-            # Elasticsearch won't get all results so we default to size: 10 if
-            # stop not given.
-            s._extra["from"] = n.start or 0
-            s._extra["size"] = max(
-                0, n.stop - (n.start or 0) if n.stop is not None else 10
-            )
-            return s
+            slice_start = n.start
+            slice_stop = n.stop
         else:  # This is an index lookup, equivalent to slicing by [n:n+1].
             # If negative index, abort.
             if n < 0:
                 raise ValueError("Search does not support negative indexing.")
-            s._extra["from"] = n
-            s._extra["size"] = 1
-            return s
+            slice_start = n
+            slice_stop = n + 1
+        # Elasticsearch won't get all results so we default to size: 10 if
+        # stop not given.
+        old_from = s._extra.get("from", 0)
+        old_to = old_from + s._extra.get(
+            "size", slice_stop or (slice_start or old_from) + 10
+        )
+        new_from = old_from + (slice_start or 0)
+        new_to = (
+            min(old_to, old_from + slice_stop) if slice_stop is not None else old_to
+        )
+        s._extra["from"] = new_from
+        s._extra["size"] = max(0, new_to - new_from)
+        return s
 
     @classmethod
     def from_dict(cls, d):

tests/_async/test_search.py

@@ -361,11 +361,17 @@ def test_slice():
     assert {"from": 3, "size": 10} == s[3:].to_dict()
     assert {"from": 0, "size": 0} == s[0:0].to_dict()
     assert {"from": 20, "size": 0} == s[20:0].to_dict()
+    assert {"from": 10, "size": 5} == s[10:][:5].to_dict()
+    assert {"from": 10, "size": 0} == s[:5][10:].to_dict()
+    assert {"from": 12, "size": 0} == s[:5][10:][2:].to_dict()
+    assert {"from": 15, "size": 0} == s[10:][:5][5:].to_dict()
 
 
 def test_index():
     s = AsyncSearch()
     assert {"from": 3, "size": 1} == s[3].to_dict()
+    assert {"from": 3, "size": 1} == s[3][0].to_dict()
+    assert {"from": 8, "size": 0} == s[3][5].to_dict()
 
 
 def test_search_to_dict():

tests/_sync/test_search.py

@@ -361,11 +361,17 @@ def test_slice():
     assert {"from": 3, "size": 10} == s[3:].to_dict()
     assert {"from": 0, "size": 0} == s[0:0].to_dict()
     assert {"from": 20, "size": 0} == s[20:0].to_dict()
+    assert {"from": 10, "size": 5} == s[10:][:5].to_dict()
+    assert {"from": 10, "size": 0} == s[:5][10:].to_dict()
+    assert {"from": 12, "size": 0} == s[:5][10:][2:].to_dict()
+    assert {"from": 15, "size": 0} == s[10:][:5][5:].to_dict()
 
 
 def test_index():
     s = Search()
     assert {"from": 3, "size": 1} == s[3].to_dict()
+    assert {"from": 3, "size": 1} == s[3][0].to_dict()
+    assert {"from": 8, "size": 0} == s[3][5].to_dict()
 
 
 def test_search_to_dict():