Use paramId for param when shortName is tilde in GRIB data (#417)

* Use paramId for param when shortName is tilde in GRIB data

docs/release_notes/version_0.9_updates.rst

@@ -1,9 +1,19 @@
 Version 0.9 Updates
 /////////////////////////
 
+
 Version 0.9.1
 ===============
 
+Fixes
+++++++
+
+- When "shortName" is "~" in the GRIB header, :func:`metadata` now returns the value of "paramId" as a str for both the "param" and "shortName" keys. Previously "~" was returned for both these keys.
+
+
+Version 0.9.0
+===============
+
 New features
 ++++++++++++++++
 

src/earthkit/data/readers/grib/metadata.py

@@ -349,7 +349,13 @@ def _key_name(key):
         if not raise_on_missing:
             _kwargs["default"] = default
 
-        return self._handle.get(_key_name(key), ktype=astype, **_kwargs)
+        key = _key_name(key)
+
+        # special case when  "shortName" is "~".
+        v = self._handle.get(key, ktype=astype, **_kwargs)
+        if key == "shortName" and v == "~":
+            v = self._handle.get("paramId", ktype=str, **_kwargs)
+        return v
 
     def _is_custom_key(self, key):
         return key in self.CUSTOM_KEYS

tests/grib/test_grib_metadata.py

@@ -547,6 +547,18 @@ def test_message(fl_type, array_backend):
     assert v[:4] == b"GRIB"
 
 
+@pytest.mark.parametrize("fl_type", ["file"])
+@pytest.mark.parametrize("array_backend", [None])
+def test_grib_tilde_shortname(fl_type, array_backend):
+    f = load_grib_data("tilde_shortname.grib", fl_type, array_backend, folder="data")
+
+    assert f[0].metadata("shortName") == "106"
+    assert f[0].metadata("shortName", astype=int) == 0
+    assert f[0].metadata("paramId") == 106
+    assert f[0].metadata("paramId", astype=int) == 106
+    assert f[0].metadata("param") == "106"
+
+
 if __name__ == "__main__":
     from earthkit.data.testing import main