Redis：如何有效地检查空嵌套键

Question

我的 redis 存储中有一个嵌套字典，需要找到 key_2 == "" 然后 return 值在 key_3 中的所有记录。然后所有 key_3 值将用于运行 mysql 查询以获取 key_2 值并更新 redis 存储。

[
  ...
  task_44903: {"key_1": 44903, "key_2": "", "key_3": 1}
  task_44229: {"key_1": 44229, "key_2": 4, "key_3": 2}
  ...
]

我目前的实现方式是

    keys = r.keys(pattern='task_*')
    key_3 = set()
    for key in keys:
        values = r.get(key).decode('utf-8')
        values = ast.literal_eval(values)
        if values['key_2'] == '':
            key_3.add(values['key_3'])

有没有更简洁的方法来实现这个？

Answer 1

修改它以适合您的管道。

from itertools import chain


tasks = [
  {'task_44903': {"key_1": 44903, "key_2": "", "key_3": 1}},
  {'task_44229': {"key_1": 44229, "key_2": 4, "key_3": 2}}
]


def check_empty_key(tasks):
    # Your desired return value
    key_3s = set()

    # Makes a list of [{key_1:..., key_2:...}, {key_1:..., key_2:...}]
    task_details = chain.from_iterable(task.values() for task in tasks)
    # Iterate through each of these dictionaries
    for task_detail in task_details:
        # Will evaluate to True if task_detail['key_2'] is an empty string
        if not task_detail['key_2']:
            # Adds to the key_3s set
            key_3s.add(task_detail['key_3'])
            break
    else:
        # If no break statement was hit in the for loop, then raise this error
        raise ValueError('No empty key_2 in tasks')
    return key_3s

你也可以这样做：

def check_empty_key(tasks):
    key_3s = set()
    task_details = chain.from_iterable(task.values() for task in tasks)
    for task_detail in task_details:
        if not task_detail['key_2']:
            key_3s.add(task_detail['key_3'])
    return key_3s

但我喜欢 else 这样当我需要将它添加到我的控制流中时我可以引发错误。

Answer 2

我不确定这是不是你想要的。

data = [
  {'task_44903': {"key_1": 44903, "key_2": "", "key_3": 1}},
  {'task_44229': {"key_1": 44229, "key_2": "", "key_3": 1}},
  {'task_44230': {"key_1": 44229, "key_2": "", "key_3": 2}}
]

set([ v['key_3'] for item in data for _, v in item.items()  if v['key_2']==""])

输出

{1, 2}

Redis：如何有效地检查空嵌套键

Redis: how to efficiently check for empty nested key

python

redis

redis-py