Aggregation bugfix (#281)

**Description:**
- Two bug fixes for the aggregation logic

**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

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+- Aggregation bug fixes [#281](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/281)
+
 ## [v3.0.0a3] - 2024-07-17
 
 ### Added

stac_fastapi/core/stac_fastapi/core/extensions/aggregation.py

@@ -271,7 +271,7 @@ def metric_agg(self, es_aggs, name, data_type):
     def get_filter(self, filter, filter_lang):
         """Format the filter parameter in cql2-json or cql2-text."""
         if filter_lang == "cql2-text":
-            return orjson.loads(unquote_plus(to_cql2(parse_cql2_text(filter))))
+            return orjson.loads(to_cql2(parse_cql2_text(filter)))
         elif filter_lang == "cql2-json":
             if isinstance(filter, str):
                 return orjson.loads(unquote_plus(filter))
@@ -447,6 +447,8 @@ async def aggregate(
                         status_code=400,
                         detail=f"Aggregation {agg_name} not supported at catalog level",
                     )
+
+        if aggregate_request.filter:
             try:
                 search = self.database.apply_cql2_filter(
                     search, aggregate_request.filter

stac_fastapi/tests/extensions/test_aggregation.py

@@ -176,6 +176,19 @@ async def test_aggregate_filter_extension_eq_post(app_client, ctx):
     assert resp.json()["aggregations"][0]["value"] == 1
 
 
+@pytest.mark.asyncio
+async def test_aggregate_filter_extension_neq_post(app_client, ctx):
+    params = {
+        "filter": {"op": "<>", "args": [{"property": "id"}, ctx.item["id"]]},
+        "filter-lang": "cql2-json",
+        "aggregations": ["total_count"],
+        "collections": [ctx.item["collection"]],
+    }
+    resp = await app_client.post("/aggregate", json=params)
+    assert resp.status_code == 200
+    assert resp.json()["aggregations"][0]["value"] == 0
+
+
 @pytest.mark.asyncio
 async def test_aggregate_extension_gte_get(app_client, ctx):
     # there's one item that can match, so one of these queries should match it and the other shouldn't