fields: don't cast items fields values to string (#54976)

tests/api/test_formdef.py

@@ -640,6 +640,7 @@ def test_formdef_submit_with_varname(pub, local_user):
         fields.MapField(id='5', label='foobar5', varname='map'),
         fields.StringField(id='6', label='foobar6', varname='foobar6'),
         fields.TableField(id='7', label='table', varname='table', rows=['Person1', 'Person2'], cols=['Name']),
+        fields.ItemsField(id='8', label='items', varname='items', items=['value']),
     ]
     formdef.store()
     data_class = formdef.data_class()
@@ -675,6 +676,7 @@ def test_formdef_submit_with_varname(pub, local_user):
                 'lon': 2.25,
             },
             'table': [['Name1'], ['Name2']],
+            'items': '["a"]',
         }
     }
     resp = get_app(pub).post_json(url, payload)
@@ -694,6 +696,7 @@ def test_formdef_submit_with_varname(pub, local_user):
     assert data_class.get(resp.json['data']['id']).data['4'].orig_filename == 'test.txt'
     assert data_class.get(resp.json['data']['id']).data['4'].get_content() == b'test'
     assert data_class.get(resp.json['data']['id']).data['5'] == '1.5;2.25'
+    assert data_class.get(resp.json['data']['id']).data['8'] == []
     # test bijectivity
     assert (
         formdef.fields[3].get_json_value(data_class.get(resp.json['data']['id']).data['3'])

wcs/fields.py

@@ -2397,6 +2397,11 @@ class ItemsField(WidgetField, ItemFieldMixin):
                     field['items'] = [item['text'] for item in structured_items]
         return field
 
+    def from_json_value(self, value):
+        if isinstance(value, list):
+            return value
+        return []
+
 
 register_field_class(ItemsField)