From 7e2b5d06a8cb5fc75866a7e948c76e2b1d6b2048 Mon Sep 17 00:00:00 2001
From: Norman Fomferra <norman.fomferra@brockmann-consult.de>
Date: Wed, 14 Dec 2022 11:05:20 +0100
Subject: [PATCH] fixed grid_mapping of computed ml datasets

---
 test/core/mldataset/test_computed.py |  6 +++++-
 xcube/core/mldataset/computed.py     | 19 ++++++++++++++++---
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/test/core/mldataset/test_computed.py b/test/core/mldataset/test_computed.py
index 4bddb1a6c..9cec68f3c 100644
--- a/test/core/mldataset/test_computed.py
+++ b/test/core/mldataset/test_computed.py
@@ -115,8 +115,12 @@ def assert_computed_ml_dataset_ok(
             self,
             computed_ml_ds: ComputedMultiLevelDataset
     ):
-        # assert output is same as input
         self.assertEqual(3, computed_ml_ds.num_levels)
+        self.assertEqual(1, computed_ml_ds.num_inputs)
+        self.assertEqual(computed_ml_ds.grid_mapping,
+                         computed_ml_ds.get_input_dataset(0).grid_mapping)
+
+        # assert output is same as input
         base_dataset = computed_ml_ds.get_dataset(0)
         self.assertEqual({'lon', 'lat',
                           'lat_bnds', 'lon_bnds',
diff --git a/xcube/core/mldataset/computed.py b/xcube/core/mldataset/computed.py
index d851afcc1..87b2779fa 100644
--- a/xcube/core/mldataset/computed.py
+++ b/xcube/core/mldataset/computed.py
@@ -27,6 +27,7 @@
 
 from xcube.core.byoa import CodeConfig
 from xcube.core.byoa import FileSet
+from xcube.core.gridmapping import GridMapping
 from xcube.util.assertions import assert_given
 from xcube.util.assertions import assert_instance
 from xcube.util.assertions import assert_true
@@ -137,11 +138,23 @@ def get_callable(
 
         return callable_ref, callable_obj
 
+    @property
+    def num_inputs(self) -> int:
+        return len(self._input_ml_dataset_ids)
+
+    def get_input_dataset(self, index: int) -> MultiLevelDataset:
+        return self._input_ml_dataset_getter(
+            self._input_ml_dataset_ids[index]
+        )
+
     def _get_num_levels_lazily(self) -> int:
-        ds_0 = self._input_ml_dataset_getter(self._input_ml_dataset_ids[0])
-        return ds_0.num_levels
+        return self.get_input_dataset(0).num_levels
+
+    def _get_grid_mapping_lazily(self) -> GridMapping:
+        return self.get_input_dataset(0).grid_mapping
 
-    def _get_dataset_lazily(self, index: int,
+    def _get_dataset_lazily(self,
+                            index: int,
                             parameters: Dict[str, Any]) -> xr.Dataset:
         input_datasets = [
             self._input_ml_dataset_getter(ds_id).get_dataset(index)