Do not drop service request num to 0 on the chart for the periods when serving model was not reporting

apiserver/bll/serving/stats.py

@@ -270,15 +270,20 @@ class ServingStats:
                 }
             },
         }
+        hist_params = {}
+        if metric_type == MetricType.requests:
+            hist_params["min_doc_count"] = 1
+        else:
+            hist_params["extended_bounds"] = {
+                "min": int(from_date) * 1000,
+                "max": int(to_date) * 1000,
+            }
         aggs = {
             "dates": {
                 "date_histogram": {
                     "field": "timestamp",
                     "fixed_interval": f"{interval}s",
-                    "extended_bounds": {
+                    **hist_params,
-                        "min": int(from_date) * 1000,
-                        "max": int(to_date) * 1000,
-                    },
                 },
                 "aggs": aggs,
             }

apiserver/utilities/dicts.py

@@ -1,4 +1,4 @@
-from typing import Sequence, Tuple, Any, Union, Callable, Optional, Mapping
+from typing import Sequence, Tuple, Any, Union, Callable, Optional, Protocol
 
 
 def flatten_nested_items(
@@ -35,8 +35,13 @@ def deep_merge(source: dict, override: dict) -> dict:
     return source
 
 
+class GetItem(Protocol):
+    def __getitem__(self, key: Any) -> Any:
+        pass
+
+
 def nested_get(
-    dictionary: Mapping,
+    dictionary: GetItem,
     path: Sequence[str],
     default: Optional[Union[Any, Callable]] = None,
 ) -> Any: