fix: Adding a key for technical/private data in SFEOS (#518)

**Description:**

Add the `HIDE_PRIVATE_DATA` and `PRIVATE_DATA_FIELD` environment
variables to toggle inclusion of private or technical fields in SFEOS
responses:
- `true`: hides private data
- `false`: returns full response
Improves control over sensitive data exposure while maintaining backward
compatibility.

**PR Checklist:**

- [x] Code is formatted and linted (run `pre-commit run --all-files`)
- [x] Tests pass (run `make test`)
- [x] Documentation has been updated to reflect changes, if applicable
- [x] Changes are added to the changelog

---------

Co-authored-by: Yuri Zmytrakov <yzmytrakovNB@yzmytrakovNB.local>

Author: YuriZmytrakov

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Added
 
+- Environment variable `EXCLUDED_FROM_ITEMS` to exclude specific fields from items endpoint response. Supports comma-separated list of fully qualified field names (e.g., `properties.auth:schemes,properties.storage:schemes`) [#518](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/518)
+
 ### Changed
 
 ### Fixed

README.md

@@ -369,6 +369,8 @@ You can customize additional settings in your `.env` file:
 | `STAC_INDEX_ASSETS` | Controls if Assets are indexed when added to Elasticsearch/Opensearch. This allows asset fields to be included in search queries. | `false` | Optional |
 | `USE_DATETIME` | Configures the datetime search behavior in SFEOS. When enabled, searches both datetime field and falls back to start_datetime/end_datetime range for items with null datetime. When disabled, searches only by start_datetime/end_datetime range. | `true` | Optional |
 | `EXCLUDED_FROM_QUERYABLES` | Comma-separated list of fully qualified field names to exclude from the queryables endpoint and filtering. Use full paths like `properties.auth:schemes,properties.storage:schemes`. Excluded fields and their nested children will not be exposed in queryables. | None | Optional |
+| `EXCLUDED_FROM_ITEMS` | Specifies fields to exclude from STAC item responses. Supports comma-separated field names and dot notation for nested fields (e.g., `private_data,properties.confidential,assets.internal`). | `None` | Optional |
+
 
 > [!NOTE]
 > The variables `ES_HOST`, `ES_PORT`, `ES_USE_SSL`, `ES_VERIFY_CERTS` and `ES_TIMEOUT` apply to both Elasticsearch and OpenSearch backends, so there is no need to rename the key names to `OS_` even if you're using OpenSearch.

stac_fastapi/core/stac_fastapi/core/serializers.py

@@ -2,6 +2,7 @@
 
 import abc
 import logging
+import os
 from copy import deepcopy
 from typing import Any, List, Optional
 
@@ -10,7 +11,7 @@
 
 from stac_fastapi.core.datetime_utils import now_to_rfc3339_str
 from stac_fastapi.core.models.links import CollectionLinks
-from stac_fastapi.core.utilities import get_bool_env
+from stac_fastapi.core.utilities import get_bool_env, get_excluded_from_items
 from stac_fastapi.types import stac as stac_types
 from stac_fastapi.types.links import ItemLinks, resolve_links
 
@@ -108,7 +109,7 @@ def db_to_stac(cls, item: dict, base_url: str) -> stac_types.Item:
         else:
             assets = item.get("assets", {})
 
-        return stac_types.Item(
+        stac_item = stac_types.Item(
             type="Feature",
             stac_version=item.get("stac_version", ""),
             stac_extensions=item.get("stac_extensions", []),
@@ -121,6 +122,14 @@ def db_to_stac(cls, item: dict, base_url: str) -> stac_types.Item:
             assets=assets,
         )
 
+        excluded_fields = os.getenv("EXCLUDED_FROM_ITEMS")
+        if excluded_fields:
+            for field_path in excluded_fields.split(","):
+                if field_path := field_path.strip():
+                    get_excluded_from_items(stac_item, field_path)
+
+        return stac_item
+
 
 class CollectionSerializer(Serializer):
     """Serialization methods for STAC collections."""

stac_fastapi/core/stac_fastapi/core/utilities.py

@@ -178,3 +178,20 @@ def dict_deep_update(merge_to: Dict[str, Any], merge_from: Dict[str, Any]) -> No
             dict_deep_update(merge_to[k], merge_from[k])
         else:
             merge_to[k] = v
+
+
+def get_excluded_from_items(obj: dict, field_path: str) -> None:
+    """Remove a field from items.
+
+    The field is removed in-place from the dictionary if it exists.
+    If any intermediate path does not exist or is not a dictionary,
+    the function returns without making any changes.
+    """
+    *path, final = field_path.split(".")
+    current = obj
+    for part in path:
+        current = current.get(part, {})
+        if not isinstance(current, dict):
+            return
+
+    current.pop(final, None)

stac_fastapi/tests/api/test_api.py

@@ -1657,3 +1657,56 @@ async def test_use_datetime_false(app_client, load_test_data, txn_client, monkey
 
     assert "test-item-datetime-only" not in found_ids
     assert "test-item-start-end-only" in found_ids
+
+
+@pytest.mark.asyncio
+async def test_hide_private_data_from_item(app_client, txn_client, load_test_data):
+    os.environ["EXCLUDED_FROM_ITEMS"] = "private_data,properties.private_data"
+
+    test_collection = load_test_data("test_collection.json")
+    test_collection_id = "test-collection-private-data"
+    test_collection["id"] = test_collection_id
+    await create_collection(txn_client, test_collection)
+
+    test_item = load_test_data("test_item.json")
+    test_item_id = "test-item-private-data"
+    test_item["id"] = test_item_id
+    test_item["collection"] = test_collection_id
+    test_item["private_data"] = {"secret": "sensitive_info"}
+    test_item["properties"]["private_data"] = {"secret": "sensitive_info"}
+    await create_item(txn_client, test_item)
+
+    # Test /collections/{collection_id}/items
+    resp = await app_client.get(f"/collections/{test_collection_id}/items")
+    assert resp.status_code == 200
+    resp_json = resp.json()
+    item = resp_json["features"][0]
+    assert "private_data" not in item
+    assert "private_data" not in item["properties"]
+
+    # Test /collections/{collection_id}/items/{item_id}
+    resp = await app_client.get(
+        f"/collections/{test_collection_id}/items/{test_item_id}"
+    )
+    assert resp.status_code == 200
+    resp_json = resp.json()
+    assert "private_data" not in resp_json
+    assert "private_data" not in resp_json["properties"]
+
+    # Test GET /search
+    resp = await app_client.get(f"/search?collections={test_collection_id}")
+    assert resp.status_code == 200
+    resp_json = resp.json()
+    item = resp_json["features"][0]
+    assert "private_data" not in item
+    assert "private_data" not in item["properties"]
+
+    # Test POST /search
+    resp = await app_client.post("/search", json={"collections": [test_collection_id]})
+    assert resp.status_code == 200
+    resp_json = resp.json()
+    item = resp_json["features"][0]
+    assert "private_data" not in item
+    assert "private_data" not in item["properties"]
+
+    del os.environ["EXCLUDED_FROM_ITEMS"]