Types in Python - Google Appengine

Question

Getting a bit peeved now;

I have a model and a class thats just storing a get request in the database; basic tracking.

class SearchRec(db.Model):
  WebSite = db.StringProperty()#required=True
  WebPage = db.StringProperty()
  CountryNM = db.StringProperty()
  PrefMailing = db.BooleanProperty()
  DateStamp = db.DateTimeProperty(auto_now_add=True)
  IP = db.StringProperty()

class AddSearch(webapp.RequestHandler):
  def get(self):
    searchRec = SearchRec()

    searchRec.WebSite = self.request.get('WEBSITE')
    searchRec.WebPage = self.request.get('WEBPAGE')
    searchRec.CountryNM = self.request.get('COUNTRY')
    searchRec.PrefMailing = bool(self.request.get('MAIL'))
    searchRec.IP = self.request.get('IP')

Bool has my biscuit; I thought that setting bool(self.reque....) would set the type of the string but no matter what I pass it it still stores it as TRUE in the database. I had the same issue with using required=True on strings for the model; the damn thing kept saying that nothing was being passed... but it had.

Ta

Answer 1

You've added a lot of layers of complication to understanding what the bool() build-in function does. Why don't you test it out directly on the command-line, before embedding it deep in your google app engine code.

What you'd discover is that the bool() function uses python's truth values:

http://docs.python.org/library/stdtypes.html#truth-value-testing

The following values are considered false:

* None
* False
* zero of any numeric type, for example, 0, 0L, 0.0, 0j.
* any empty sequence, for example, '', (), [].
* any empty mapping, for example, {}.
* instances of user-defined classes, if the class defines a
   `__nonzero__()` or `__len__()` method, when that method returns the integer
   zero or bool value False. [1]

All other values are considered true — so objects of many types are always true.

In particular - any non-empty string is True.

Answer 2

Bool has my biscuit; I thought that setting bool(self.reque....) would set the type of the string but no matter what I pass it it still stores it as TRUE in the database.

Well, what's the value of self.request.get('MAIL')? If it's anything other than an empty string or None, bool will see it as True.

I had the same issue with using required=True on strings for the model; the damn thing kept saying that nothing was being passed... but it had.

If you set a property to required=True, then you must pass it to the model's constructor. So, if WebSite is a required property, you need to construct your searchRec like so:

searchRec = SearchRec(WebSite=self.request.get('WEBSITE'))