Question

我正在尝试创建Google App Engine的数据存储区和数据库模型的基本用法。我的模型对象是

class Table(db.Model):
    row = db.IntegerProperty()
    col = db.IntegerProperty()
    date = db.DateTimeProperty(auto_now_add=True)

它将用于保存行和列的表。用户通过html提供输入，然后我保存表并绘制数据存储区中的所有表。我使用Table.all()来获取数据存储区中的所有表，然后尝试访问它们的内容，以便我可以打印表，但出于某种原因，在for y in range(row):中读取table.row和table.col时显然会返回一个noneType，有谁知道为什么？

import webapp2
from google.appengine.ext.webapp.util import run_wsgi_app
from google.appengine.ext import db
from logging import error

INITIAL_INPUT = """\
<html>
    <body>
        <form action="/out?%s" method="POST">
            <input type="text" name="row" />
            <input type="text" name="col" />
            <input type="submit" value="Submit" />
        </form>
    </body>
</html>
"""

class Table(db.Model):
    """Models an individual Guestbook entry with author, content, and date."""
    row = db.IntegerProperty()
    col = db.IntegerProperty()
    date = db.DateTimeProperty(auto_now_add=True)

class MainPage(webapp2.RequestHandler):
    def get(self):
        self.response.write(INITIAL_INPUT)

class Out(webapp2.RequestHandler):

    def post(self):
        newRow = self.request.POST['row']
        newCol = self.request.POST['col']
        newTable = Table()
        newTable.row = int(newRow) if newRow else 1
        newTable.col = int(newCol) if newCol else 1 
        newTable.put()
        tables = Table.all()
        for table in tables:
            self.drawTable(table.row, table.col)


    def drawTable(self, row , col):
        write = self.response.write
        write("<html><body><table>")
        for y in range(row):
            write("<tr>")
            for x in range(col):
                cell = "<td bgcolor=\"#00FF00\">" + str(x) + " " + str(y) + "</td>"
                if x % 2 == 0:
                    cell = "<td bgcolor=\"#FF0000\">" + str(x) + " " + str(y) + "</td>"
                write(cell)
            write("</tr>")    
        write("</table></body></html>")  

application = webapp2.WSGIApplication([
    ('/', MainPage),
    ('/out', Out)]
, debug=True)

def main(*args, **kwds):
    run_wsgi_app(application)


if __name__ == "__main__":
    main()

Answer 1

注意：<form action="/out?%s"不正确，只需action="/out"。

我敢打赌你在Table中有其他实体，所以你的循环会选择它们。使用数据存储查看器查看By kind: Table并删除具有空行，列值的那些。

也许您只想绘制已发布的表格？改变这些行：

    tables = Table.all()
    for table in tables:
        self.drawTable(table.row, table.col)

为：

    self.drawTable(newTable.row, newTable.col)

Google App Engine数据存储区模型属性不返回任何内容

1 个答案: