Bug fix for ComputedEntry from_dict (#3897)

* fix bug in ComputedEntry.from_dict when kwargs are null, add test

* linting

* slight refactor

* clearer legacy case

pymatgen/entries/computed_entries.py

@@ -482,27 +482,26 @@ def from_dict(cls, dct: dict) -> Self:
         Returns:
             ComputedEntry
         """
-        # the first block here is for legacy ComputedEntry that were
-        # serialized before we had the energy_adjustments attribute.
-        if dct["correction"] != 0 and not dct.get("energy_adjustments"):
-            return cls(
-                dct["composition"],
-                dct["energy"],
-                dct["correction"],
-                parameters={k: MontyDecoder().process_decoded(v) for k, v in dct.get("parameters", {}).items()},
-                data={k: MontyDecoder().process_decoded(v) for k, v in dct.get("data", {}).items()},
-                entry_id=dct.get("entry_id"),
-            )
+        # Must handle cases where some kwargs exist in `dct` but are None
+        # include extra logic to ensure these get properly treated
+        energy_adj = [MontyDecoder().process_decoded(e) for e in (dct.get("energy_adjustments", []) or [])]
+
         # this is the preferred / modern way of instantiating ComputedEntry
         # we don't pass correction explicitly because it will be calculated
         # on the fly from energy_adjustments
+        correction = 0
+        if dct["correction"] != 0 and len(energy_adj) == 0:
+            # this block is for legacy ComputedEntry that were
+            # serialized before we had the energy_adjustments attribute.
+            correction = dct["correction"]
+
         return cls(
             dct["composition"],
             dct["energy"],
-            correction=0,
-            energy_adjustments=[MontyDecoder().process_decoded(e) for e in dct.get("energy_adjustments", {})],
-            parameters={k: MontyDecoder().process_decoded(v) for k, v in dct.get("parameters", {}).items()},
-            data={k: MontyDecoder().process_decoded(v) for k, v in dct.get("data", {}).items()},
+            correction=correction,
+            energy_adjustments=energy_adj,
+            parameters={k: MontyDecoder().process_decoded(v) for k, v in (dct.get("parameters", {}) or {}).items()},
+            data={k: MontyDecoder().process_decoded(v) for k, v in (dct.get("data", {}) or {}).items()},
             entry_id=dct.get("entry_id"),
         )
 

tests/entries/test_computed_entries.py

@@ -238,6 +238,19 @@ def test_copy(self):
             assert entry == copy
             assert str(entry) == str(copy)
 
+    def test_from_dict_null_fields(self):
+        ce_dict = self.entry.as_dict()
+        for k in (
+            "energy_adjustments",
+            "parameters",
+            "data",
+        ):
+            ce = ce_dict.copy()
+            ce[k] = None
+            new_ce = ComputedEntry.from_dict(ce)
+            assert new_ce == self.entry
+            assert getattr(new_ce, k, None) is not None
+
 
 class TestComputedStructureEntry(TestCase):
     def setUp(self):