python - BadValueError : Property xxxx is required, 即使已经设置了 xxxx 属性？ (谷歌应用引擎)

Question

这是我的模型:

from google.appengine.ext import db
from google.appengine.ext.db import polymodel

class Item(polymodel.PolyModel):
    title = db.StringProperty(required=True)
    summary = db.StringProperty(required=True)
    content = db.TextProperty(required=True)
    createDate = db.DateTimeProperty(auto_now_add=True)

class Article(Item):
    author = db.StringProperty()

和我的处理程序:

from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app
import models.model

class Test(webapp.RequestHandler):

    def get(self):
        create(100)
        self.response.headers['Content-Type'] = 'text/plain'
        self.response.out.write('Test')
        self.response.out.write('<p>Created')


app = webapp.WSGIApplication([('/test/*', Test)], debug=True)

def create(count):
    for i in range(0,count,1):
        article = models.model.Article()
        article.title = "Test title " + str(i)
        article.author = "wliao"
        article.summary = "this is a test " + str(i)
        article.content = "this is the content of the article"
        article.put()    

def main():
    run_wsgi_app(app)

if __name__ == "__main__":
    main()

我的问题是，我已经设置了所需的属性，为什么在浏览器中加载它时仍然会出现此错误:

追溯(最近的调用最后): 文件“/home/wliao/Programming/GoogleAppEngineSDK/google/appengine/ext/webapp/init.py”，第 700 行，在 call handler.get(*组) 文件“/home/wliao/Programming/MysteryLeague/src/controllers/test.py”，第 8 行，在 get 创建(100) 创建文件“/home/wliao/Programming/MysteryLeague/src/controllers/test.py”，第 18 行 文章 = models.model.Article() 文件“/home/wliao/Programming/GoogleAppEngineSDK/google/appengine/ext/db/init.py”，第 910 行，在 init prop.set( self , 值(value)) 文件“/home/wliao/Programming/GoogleAppEngineSDK/google/appengine/ext/db/init.py”，第 594 行，在 set 中 值 = self.validate(值) 文件“/home/wliao/Programming/GoogleAppEngineSDK/google/appengine/ext/db/init.py”，第 2627 行，在验证中 value = super(UnindexedProperty, self).validate(value) 文件“/home/wliao/Programming/GoogleAppEngineSDK/google/appengine/ext/db/init.py”，第 621 行，在验证中 raise BadValueError('需要属性 %s' % self.name) BadValueError:需要属性内容

谢谢!

Answer 1

来自 the docs :

Because validation occurs when the instance is constructed, any property that is configured to be required must be initialized in the constructor.

所以:

title = "Test title " + str(i)
author = "wliao"
summary = "this is a test " + str(i)
content = "this is the content of the article"

article = models.model.Article(title=title, author=author,
                               summary=summary, content=content)