Don't update a full taxon record with a partial one

pyinaturalist_convert/_models.py

@@ -229,14 +229,18 @@ def to_model(self) -> Taxon:
         )
 
     def update(self, taxon: Taxon):
-        """Update an existing record"""
+        """Merge new values into an existing record"""
+        # Don't update a full taxon record with a partial one
+        if self.partial is False and taxon._partial is True:
+            return
+
         new_taxon = self.from_model(taxon)
         for col in [c.name for c in inspect(self).mapper.columns]:
-            if not (new_val := getattr(new_taxon, col)):
+            if (new_val := getattr(new_taxon, col)) is None:
                 continue
             if col not in PRECOMPUTED_COLUMNS:
                 setattr(self, col, new_val)
-            # Precomputed columns: Don't overwrite non-null values
+            # Precomputed columns: Only overwrite null values
             elif getattr(self, col) in [None, 0]:
                 setattr(self, col, new_val)
 

test/test_db.py

@@ -173,3 +173,28 @@ def test_save_taxa__preserve_precomputed_cols(tmp_path):
     assert results[0].observations_count == 18017625
     assert results[1].complete_species_count == 416
     assert results[1].observations_count == 218279
+
+
+def test_save_taxa__partial(tmp_path):
+    db_path = tmp_path / 'observations.db'
+    taxon_1 = Taxon(
+        id=3,
+        name='Aves',
+        rank='class',
+        preferred_common_name='Birds',
+        complete_species_count=10672,
+        observations_count=18017625,
+    )
+
+    create_tables(db_path)
+    save_taxa([taxon_1], db_path=db_path)
+
+    # Save with updated values for precomputed columns
+    taxon_1.preferred_common_name = 'updated!'
+    taxon_1._partial = True
+    save_taxa([taxon_1], db_path=db_path)
+
+    # Only previously null values (taxon_2.observations_count) in DB should be updated
+    results = list(get_db_taxa(db_path))
+    assert results[0].preferred_common_name == 'Birds'
+    assert results[0]._partial is False