tinydb:如何使用条件更新文档

Question

嗨，我想更新一些与查询相匹配的文档。因此，对于每个文档，我想更新字段'parent_id'当且仅当该文档具有ID greater then，即6

        for result in results:
            db.update(set('parent_id', current_element_id), 
                      result.get('id') > current_element_id )

错误：

Traceback (most recent call last):
  File "debug.py", line 569, in <module>
    convertxml=parse(xmlfile, force_list=('interface',))
  File "debug.py", line 537, in parse
    parser.Parse(xml_input, True)
  File "..\Modules\pyexpat.c", line 468, in EndElement
  File "debug.py", line 411, in endElement
    db.update(set('parent_id', current_element_id), result.get('id') > current_element_id )
  File "C:\ProgramData\Miniconda3\lib\site-packages\tinydb\database.py", line 477, in update
    cond, doc_ids
  File "C:\ProgramData\Miniconda3\lib\site-packages\tinydb\database.py", line 319, in process_elements
    if cond(data[doc_id]):
TypeError: 'bool' object is not callable

应更新的文件示例：

...,
{'URI': 'http://www.john-doe/',
 'abbr': 'IDD',
 'affiliation': 'USA',
 'closed': False,
 'created': '2018-06-01 22:49:02.927347',
 'element': 'distrbtr',
 'id': 7,
 'parent_id': None
 },...

在文档 of tinydb中，我看到可以使用set。否则，如果我不使用Set，它将更新all，document db.update(dict)，这是我不想要的。

Answer 1

使用使用write_back的文档对文档的替换部分更好

>>> docs = db.search(User.name == 'John')
[{name: 'John', age: 12}, {name: 'John', age: 44}]
>>> for doc in docs:
...     doc['name'] = 'Jane'
>>> db.write_back(docs)  # Will update the documents we retrieved
>>> docs = db.search(User.name == 'John')
[]
>>> docs = db.search(User.name == 'Jane')
[{name: 'Jane', age: 12}, {name: 'Jane', age: 44}]

在我的情况下实施

for result in results:
    if result['parent_id'] != None:
        result['parent_id']  = current_element_id
db.write_back(results)