filter by model id in forecast value lates table (#186)

* filter by model id in forecast value lates table

* fix

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: peterdudfield

nowcasting_datamodel/read/read.py

@@ -309,11 +309,6 @@ def get_latest_forecast_for_gsps(
     # filter on historic
     query = query.filter(ForecastSQL.historic == historic)
 
-    # filter on model name
-    if model_name is not None:
-        query = query.join(MLModelSQL)
-        query = query.filter(MLModelSQL.name == model_name)
-
     # filter on target time
     if start_target_time is not None:
         query = filter_query_on_target_time(
@@ -323,6 +318,17 @@ def get_latest_forecast_for_gsps(
             end_target_time=end_target_time,
         )
 
+    # filter on model name
+    if model_name is not None:
+        if historic:
+            # if start target time is None, we need to join with forecast value latest
+            if start_target_time is None:
+                query = query.join(ForecastValueLatestSQL)
+            query = query.join(MLModelSQL, ForecastValueLatestSQL.model_id == MLModelSQL.id)
+        else:
+            query = query.join(MLModelSQL)
+        query = query.filter(MLModelSQL.name == model_name)
+
     query = query.join(LocationSQL)
 
     # option to preload values, makes querying quicker