Fix #1722: TypeError: Expected str for time_str, got datetime (PR #1723)

pdr_backend/ppss/lake_ss.py

@@ -51,15 +51,21 @@ def lake_dir(self) -> str:
 
     @property
     def st_timestr(self) -> str:
-        return self.d["st_timestr"]  # eg "2019-09-13_04:00" (earliest)
+        s = self.d["st_timestr"]  # eg "2019-09-13_04:00" (earliest)
+        assert isinstance(s, str)
+        return s
 
     @property
     def fin_timestr(self) -> str:
-        return self.d["fin_timestr"]  # eg "now","2023-09-23_17:55","2023-09-23"
+        s = self.d["fin_timestr"]  # eg "now","2023-09-23_17:55","2023-09-23"
+        assert isinstance(s, str)
+        return s
 
     @property
     def api(self) -> str:
-        return self.d.get("api", "ccxt")
+        s = self.d.get("api", "ccxt")
+        assert isinstance(s, str)
+        return s
 
     # feeds defined in base
 

pdr_backend/ppss/ppss.py

@@ -3,6 +3,7 @@
 from typing import Optional, Tuple
 
 import yaml
+import yaml.constructor
 from enforce_typing import enforce_types
 
 from pdr_backend.cli.predict_train_feedsets import PredictTrainFeedsets
@@ -81,8 +82,12 @@ def constructor_dict(
             yaml_filename or yaml_str and not (yaml_filename and yaml_str)
         ), "need to set yaml_filename_ or yaml_str but not both"
 
+        # Specify yaml.safe_load to _not_ convert strings to timestamps
+        c = yaml.constructor.SafeConstructor.yaml_constructors
+        c["tag:yaml.org,2002:timestamp"] = c["tag:yaml.org,2002:str"]
+
         # get d
-        if yaml_filename is not None:
+        if yaml_filename:
             with open(yaml_filename, "r") as f:
                 d = yaml.safe_load(f)
         else: