ENH: Update multiple rows in files and DBs with data.update

Closes #312

gramex/data.py

@@ -741,13 +741,10 @@ def _filter_frame(data, meta, controls, args, source='select', id=[]):
             # Apply filters
             data = _filter_frame_col(data, key, col, op, vals, meta)
         elif source == 'update':
-            # Update values should only contain 1 value. 2nd onwards are ignored
             if key not in data.columns or len(vals) == 0:
                 meta['ignored'].append((key, vals))
             else:
-                cols_for_update[key] = vals[0]
-                if len(vals) > 1:
-                    meta['ignored'].append((key, vals[1:]))
+                cols_for_update[key] = vals
         else:
             meta['ignored'].append((key, vals))
     meta['count'] = len(data)
@@ -868,20 +865,24 @@ def _filter_db(engine, table, meta, controls, args, source='select', id=[]):
             query = _filter_db_col(query, query.where, key, col, op, vals,
                                    cols[col], cols[col].type.python_type, meta)
         elif source == 'update':
-            # Update values should only contain 1 value. 2nd onwards are ignored
             if key not in cols or len(vals) == 0:
                 meta['ignored'].append((key, vals))
             else:
-                cols_for_update[key] = vals[0]
-                if len(vals) > 1:
-                    meta['ignored'].append((key, vals[1:]))
+                cols_for_update[key] = vals
         else:
             meta['ignored'].append((key, vals))
     if source == 'delete':
         res = engine.execute(query)
         return res.rowcount
     elif source == 'update':
-        query = query.values(cols_for_update)
+        id_name = id[0]
+        id_col = getattr(table.c, id_name)
+        cases = {
+            k: sa.case(
+                [(id_col == i, j) for i, j in zip(args[id_name], v)]
+            ) for k, v in cols_for_update.items()
+        }
+        query = query.values(**cases)
         res = engine.execute(query)
         return res.rowcount
     else:

testlib/test_data.py

@@ -597,6 +597,49 @@ def test_update(self):
         gramex.data.update(data, args=args, id=['देश', 'city', 'product'])
         ase(types_original, data.dtypes)
 
+    def test_update_multiple_file(self):
+        # Test on a file
+
+        update_file = os.path.join(folder, 'actors.update.csv')
+        shutil.copy(os.path.join(folder, '..', 'tests/actors.csv'), update_file)
+        self.tmpfiles.append(update_file)
+
+        names = ['Humphrey Bogart', 'James Stewart', 'Audrey Hepburn']
+        categories = ['Stars', 'Thespians', 'Heartthrobs']
+        ratings = [1, 0.99, 1.11]
+        gramex.data.update(
+            update_file,
+            args={
+                'name': names,
+                'category': categories,
+                'rating': ratings
+            }, id=['name']
+        )
+        df = gramex.data.filter(update_file, args={'name': names})
+        self.assertEqual(df['category'].tolist(), categories)
+        self.assertEqual(df['rating'].tolist(), ratings)
+
+    def test_update_multiple_db(self):
+        actors = gramex.cache.open(os.path.join(folder, '../tests/actors.csv'))
+        temp_db = f'sqlite:///{folder}/actors.db'
+        self.tmpfiles.append(os.path.join(folder, 'actors.db'))
+        actors.to_sql('actors', sa.create_engine(temp_db), index=False)
+
+        names = ['Humphrey Bogart', 'James Stewart', 'Audrey Hepburn']
+        categories = ['Stars', 'Thespians', 'Heartthrobs']
+        ratings = [1, 0.99, 1.11]
+        gramex.data.update(
+            temp_db,
+            args={
+                'name': names,
+                'category': categories,
+                'rating': ratings
+            }, id=['name'], table='actors'
+        )
+        df = gramex.data.filter(temp_db, args={'name': names}, table='actors')
+        self.assertEqual(df['category'].tolist(), categories)
+        self.assertEqual(df['rating'].tolist(), ratings)
+
     def test_delete(self):
         raise SkipTest('TODO: write delete test cases')