handle empty string case, eject from like optimization

tests/trace/test_client_trace.py

@@ -3373,7 +3373,7 @@ def test_call_stream_query_heavy_query_batch(client):
             parent_id=parent_id,
             started_at=datetime.datetime.now(tz=datetime.timezone.utc)
             - datetime.timedelta(seconds=1),
-            attributes={"a": 5},
+            attributes={"a": 5, "empty": "", "null": None},
             inputs={"param": {"value1": "hello"}},
         )
         client.server.call_start(tsi.CallStartReq(start=start))
@@ -3454,3 +3454,15 @@ def test_call_stream_query_heavy_query_batch(client):
     for call in res:
         assert call.inputs["param"]["value1"] == "helslo"
         assert call.output["d"] == 5
+
+    # now try to filter by the empty attribute string
+    query = {
+        "project_id": project_id,
+        "query": {
+            "$expr": {"$eq": [{"$getField": "attributes.empty"}, {"$literal": ""}]}
+        },
+    }
+    res = client.server.calls_query_stream(tsi.CallsQueryReq.model_validate(query))
+    assert len(list(res)) == 10
+    for call in res:
+        assert call.attributes["empty"] == ""

tests/trace_server/test_calls_query_builder.py

@@ -1259,3 +1259,41 @@ def test_calls_query_with_combined_like_optimizations_and_op_filter() -> None:
             "pb_12": '%"0.8"%',
         },
     )
+
+
+def test_calls_query_filter_by_empty_str() -> None:
+    cq = CallsQuery(project_id="project")
+    cq.add_field("id")
+    cq.add_field("inputs")
+    cq.add_condition(
+        tsi_query.EqOperation.model_validate(
+            {"$eq": [{"$getField": "inputs.param.val"}, {"$literal": ""}]}
+        )
+    )
+    # Empty string is not a valid value for LIKE optimization, this test is to ensure that
+    # the query builder uses the JSON_VALUE function in the WHERE.
+    assert_sql(
+        cq,
+        """
+        SELECT
+            calls_merged.id AS id,
+            any(calls_merged.inputs_dump) AS inputs_dump
+        FROM calls_merged
+        WHERE
+            calls_merged.project_id = {pb_2:String}
+        AND
+            ((JSON_VALUE(calls_merged.inputs_dump, {pb_0:String}) = {pb_1:String})
+             OR calls_merged.inputs_dump IS NULL)
+        GROUP BY (calls_merged.project_id, calls_merged.id)
+        HAVING (
+            ((JSON_VALUE(any(calls_merged.inputs_dump), {pb_0:String}) = {pb_1:String}))
+            AND ((any(calls_merged.deleted_at) IS NULL))
+            AND ((NOT ((any(calls_merged.started_at) IS NULL))))
+        )
+        """,
+        {
+            "pb_0": '$."param"."val"',
+            "pb_1": "",
+            "pb_2": "project",
+        },
+    )

weave/trace_server/calls_query_builder.py

@@ -1075,6 +1075,9 @@ def _create_like_optimized_eq_condition(
 
     field = get_field_by_name(operation.eq_[0].get_field_).field
     literal_value = operation.eq_[1].literal_
+    if not literal_value:
+        # Empty string is not a valid value for LIKE optimization
+        return None
     like_pattern = f'%"{literal_value}"%'
 
     return _create_like_condition(field, like_pattern, pb, table_alias)
@@ -1098,6 +1101,9 @@ def _create_like_optimized_contains_condition(
 
     field = get_field_by_name(operation.contains_.input.get_field_).field
     substr_value = operation.contains_.substr.literal_
+    if not substr_value:
+        # Empty string is not a valid value for LIKE optimization
+        return None
     case_insensitive = operation.contains_.case_insensitive or False
     like_pattern = f'%"%{substr_value}%"%'
 
@@ -1130,8 +1136,10 @@ def _create_like_optimized_in_condition(
     like_conditions: list[str] = []
 
     for value_operand in operation.in_[1]:
-        if not isinstance(value_operand, tsi_query.LiteralOperation) or not isinstance(
-            value_operand.literal_, str
+        if (
+            not isinstance(value_operand, tsi_query.LiteralOperation)
+            or not isinstance(value_operand.literal_, str)
+            or not value_operand.literal_
         ):
             return None