通过ndb.Model构造函数填充StructuredProperty的最佳实践是什么? [英] What is the best practice to populate a StructuredProperty through the ndb.Model constructor?

问题描述

我查看了ndb GitHub示例代码，但找不到任何示例 其中显示了如何使用包含StructuredProperty的构造函数创建ndb实体.

I looked into the ndb GitHub sample code, but I couldn't find any example which shows on how to create a ndb entity with a constructor that contains a StructuredProperty.

这是GitHub 示例.

如果我想用电话号码列表初始化Contact实体，而该电话号码列表不是PhoneNumber对象列表，该怎么办.相反，它是Python词典的列表.

What if I want to initialize a Contact entity with a list of phone numbers and this list of phone number is not a list of PhoneNumber objects. Instead it is a list of Python dictionaries.

因此，给定以下Model类:

class PhoneNumber(ndb.Model):
    """A model representing a phone number."""
    phone_type = ndb.StringProperty(
        choices=('home', 'work', 'fax', 'mobile', 'other'))
    number = ndb.StringProperty()


class Contact(ndb.Model):
    """A Contact model that uses StructuredProperty for phone numbers."""
    # Basic info.
    name = ndb.StringProperty()
    birth_day = ndb.DateProperty()

    # Address info.
    address = ndb.StringProperty()

    phone_numbers = ndb.StructuredProperty(PhoneNumber, repeated=True)

我想使用以下Python字典创建Contact:

I want to create a Contact using the following Python dictionaries:

phone_number_dicts = [{"phone_type" : "home", number = 122}, {"phone_type" : "work", number = 123}]

contact = Contact(name = "some name", birthday = "some day", phone_numbers = phone_number_dicts)

1. 我需要明确地将字典转换为ndb实体吗?
2. 我可以重写将字典转换为ndb实体并进行赋值的ndb构造函数吗?
3. 还有其他更好的方法吗?

1. Am I required to convert a dict to a ndb entity explicitly?
2. Can I override ndb constructor which converts a dict to a ndb entity and assign?
3. Any other better approach?

推荐答案

代替

phone_number_dicts = [{"phone_type" : "home", number = 122}, {"phone_type" : "work", number = 123}]
contact = Contact(name = "some name", birthday = "some day", phone_numbers = phone_number_dicts)

您需要具有以下内容:

phone_numbers = [
    PhoneNumber(phone_type="home", number=123),
    PhoneNumber(phone_type="work", number=123)
]
contact = Contact(name="some name", birthday="some day", phone_numbers=phone_numbers)

即列出PhoneNumber个实体，而不是dict个.

i.e. make a list of PhoneNumber entities rather than a list of dicts.

您也可以将字典传递给ndb实体，以便使用 populate方法，即如果您已经有了该行

You may also pass a dict to an ndb entity in order to populate it with the populate method, i.e. if you already have the line

phone_number_dicts = [{"phone_type" : "home", number = 122}, {"phone_type" : "work", number = 123}]

您无法控制，然后就可以

that you have no control over, you could then do

phone_numbers = [PhoneNumber().populate(**entity) for entity in phone_number_dicts]

从现有的dict列表中创建PhoneNumber的列表，然后将其再次传递给Contact构造函数.

to create a list of PhoneNumbers from an existing list of dicts which you then again pass to the Contact constructor.

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