json output format: more robust with respect to unknown types

Open-EO/openeo-geopyspark-driver#643

openeo_driver/save_result.py

@@ -4,6 +4,7 @@
 import tempfile
 import warnings
 import logging
+from datetime import datetime, date
 from pathlib import Path
 from shutil import copy
 from tempfile import mkstemp
@@ -171,13 +172,24 @@ def write_assets(self, directory: Union[str, Path]) -> Dict[str, StacAsset]:
 
         :return: STAC assets dictionary: https://github.com/radiantearth/stac-spec/blob/master/item-spec/item-spec.md#assets
         """
+
+        def json_serial(obj):
+            """JSON serializer for objects not serializable by default json code"""
+
+            if isinstance(obj, (datetime, date)):
+                return obj.isoformat()
+            else:
+                return str(obj)
+
+
+
         # TODO: There is something wrong here: arg is called `directory`,
         #       but implementation and actual usage handles it as a file path (take parent to get directory)
         output_dir = Path(directory).parent
         output_file = output_dir / "result.json"
         with open(output_file, 'w') as f:
             import json
-            json.dump(self.prepare_for_json(), f)
+            json.dump(self.prepare_for_json(), f,default=json_serial)
         return {"result.json":{
             "href":str(output_file),
             "roles": ["data"],

tests/test_save_result.py

@@ -1,3 +1,4 @@
+import datetime
 import json
 from pathlib import Path
 
@@ -9,7 +10,7 @@
 from openeo.metadata import CollectionMetadata
 from openeo_driver.datacube import DriverVectorCube
 from openeo_driver.save_result import AggregatePolygonResult, SaveResult, AggregatePolygonSpatialResult, \
-    AggregatePolygonResultCSV
+    AggregatePolygonResultCSV, JSONResult
 from .data import load_json, json_normalize, get_path
 
 
@@ -172,3 +173,20 @@ def test_load_csv(self):
             [4646.262612301313, 4865.926572218383, 5178.517363510712],
             [4645.719597475695, 4865.467252259935, 5177.803342998465],
         ]
+
+def test_jsonresult(tmp_path):
+
+    the_data = {
+        "bla":"bla",
+        "bla2":np.nan,
+        "bla3":{'bla':'bla'},
+        "bla4":datetime.datetime.fromisocalendar(2020,3,1)
+    }
+    JSONResult(the_data).write_assets(tmp_path/"bla")
+
+    the_path = tmp_path.joinpath("result.json")
+    actual_data = json.load(the_path.open())
+    assert { 'bla': 'bla',
+             'bla2': None,
+             'bla3': {'bla': 'bla'},
+             'bla4': '2020-01-13T00:00:00'} == actual_data