我尝试使用 Python 将嵌套的 entity/dict放入 到数据存储中，

metadata_row = dict() 
metadata_row['batch_id'] = str(uuid1()) 
metadata_row['table_ok'] = True 
metadata_row['table_name'] = 'metadata' 
metadata_row['num_rows'] = 1 
metadata_row['violations'] = [] 
metadata_row['errors'] = [] 
 
metadata_row['time'] = {} 
metadata_row['time']['total_time'] = 82.42656564712524 
metadata_row['time']['mod1'] = 5.940682411193848 
metadata_row['time']['mod2'] = 19.16786551475525 
metadata_row['time']['mod3'] = 31.617812633514404 
metadata_row['time']['mod4'] = 0.00038933753967285156 
metadata_row['time']['mod5'] = 53.35780310630798 
 
with self.client.transaction(): 
 
    entities = [Entity(self.client.key('metadata')) for i in range(len([metadata_row]))] 
 
    for entity, update_dict in zip(entities, [metadata_row]): 
        entity.update(update_dict) 
 
    self.client.put_multi(entities) 

我使用datastore emulator测试了它，但是我得到了以下错误，

ValueError: Unknown protobuf attr type <class 'dict'> 

我想知道如何解决这个问题。我还想知道 datastore 本身是否支持嵌套字典，因为它不必为内部字典创建 entity，即 time这种情况。

更新。我在 metadata_row 中为关键 time 添加了一个内部实体来解决问题。

client = datastore.Client() 
metadata_row['time'] = datastore.Entity(key=client.key('time')) 
 
metadata_row['time']['total_time'] = 82.42656564712524 
metadata_row['time']['mod1'] = 5.940682411193848 
metadata_row['time']['mod2'] = 19.16786551475525 
metadata_row['time']['mod3'] = 31.617812633514404 
metadata_row['time']['mod4'] = 0.00038933753967285156 
metadata_row['time']['mod5'] = 53.35780310630798 
 
# code for put_multi() 

请您参考如下方法:

def convert(obj, client, key): 
""" 
:param obj: dict 
:param client: datastore client 
:param key: Generated as client.key("your_table", "your_key") 
:return: datastore.Entity 
""" 
if isinstance(obj, list): 
    return [convert(item, client, None) for item in obj] 
elif isinstance(obj, dict): 
    entity = datastore.Entity(key) 
    for key in obj: 
        entity[key] = convert(obj[key], client, None) 
    return entity 
else: 
    return obj 

请提出任何改进或替代建议，因为 Google Cloud Datastore 目前没有建议将 JSON 转换为实体的方法。