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fix(nldi): return an empty GeoDataFrame instead of crashing on empty results #302

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Merged
thodson-usgs merged 1 commit into from
Jun 1, 2026
Merged

fix(nldi): return an empty GeoDataFrame instead of crashing on empty results #302

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23 changes: 19 additions & 4 deletions dataretrieval/nldi.py
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,21 @@ def _query_nldi(url, query_params, error_message):
return response_data


def _features_to_gdf(feature_collection: dict) -> gpd.GeoDataFrame:
"""Build a GeoDataFrame from an NLDI FeatureCollection, tolerating empties.

NLDI can legitimately return no features (e.g. a feature with nothing
upstream), and :func:`_query_nldi` returns ``{}`` when a 200 response
carries no JSON body. ``GeoDataFrame.from_features`` raises on those
(there's no geometry column to attach the CRS to), so return an empty
GeoDataFrame with the correct CRS instead of crashing.
"""
features = feature_collection.get("features") if feature_collection else None
if not features:
return gpd.GeoDataFrame(geometry=[], crs=_CRS)
return gpd.GeoDataFrame.from_features(feature_collection, crs=_CRS)


def get_flowlines(
navigation_mode: str,
distance: int = 5,
Expand Down Expand Up @@ -104,7 +119,7 @@ def get_flowlines(
feature_collection = _query_nldi(url, query_params, err_msg)
if as_json:
return feature_collection
gdf = gpd.GeoDataFrame.from_features(feature_collection, crs=_CRS)
gdf = _features_to_gdf(feature_collection)
return gdf


Expand Down Expand Up @@ -157,7 +172,7 @@ def get_basin(
feature_collection = _query_nldi(url, query_params, err_msg)
if as_json:
return feature_collection
gdf = gpd.GeoDataFrame.from_features(feature_collection, crs=_CRS)
gdf = _features_to_gdf(feature_collection)
return gdf


Expand Down Expand Up @@ -273,7 +288,7 @@ def get_features(
feature_collection = _query_nldi(url, query_params, err_msg)
if as_json:
return feature_collection
gdf = gpd.GeoDataFrame.from_features(feature_collection, crs=_CRS)
gdf = _features_to_gdf(feature_collection)
return gdf


Expand Down Expand Up @@ -307,7 +322,7 @@ def get_features_by_data_source(data_source: str) -> gpd.GeoDataFrame:
url = f"{NLDI_API_BASE_URL}/{data_source}"
err_msg = f"Error getting features for data source '{data_source}'"
feature_collection = _query_nldi(url, {}, err_msg)
gdf = gpd.GeoDataFrame.from_features(feature_collection, crs=_CRS)
gdf = _features_to_gdf(feature_collection)
return gdf


Expand Down
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