Attempt to fix nested model retrival

opensensor/collection_apis.py

@@ -197,14 +197,15 @@ def get_nested_fields(model: Type[BaseModel]):
     return nested_fields
 
 
-def create_nested_pipeline(model: Type[BaseModel], prefix=""):
+def create_nested_pipeline(model: Type[BaseModel], prefix="", pipeline=None):
     logger.debug(f"Creating nested pipeline for model: {model.__name__}, prefix: {prefix}")
     nested_fields = get_nested_fields(model)
     match_conditions = {}
-    pipeline = {
-        "_id": False,
-        "timestamp": "$timestamp",
-    }
+    if pipeline is None:
+        pipeline = {
+            "_id": False,
+            "timestamp": "$timestamp",
+        }
 
     for field_name, field_type in model.__fields__.items():
         if field_name == "timestamp":
@@ -240,7 +241,7 @@ def create_nested_pipeline(model: Type[BaseModel], prefix=""):
                 match_conditions[full_mongo_field_name] = {"$exists": True, "$ne": []}
             else:
                 nested_pipeline, nested_match = create_nested_pipeline(
-                    nested_fields[field_name], f"{field_name}."
+                    nested_fields[field_name], f"{full_mongo_field_name}.", pipeline
                 )
                 pipeline[field_name] = nested_pipeline
                 match_conditions.update({f"{field_name}.{k}": v for k, v in nested_match.items()})