Working datetime objects in Google App Engine

Question

In this model

class Rep(db.Model):
    mAUTHOR = db.UserProperty(auto_current_user=True)
    mUNIQUE = db.StringProperty()
    mCOUNT = db.IntegerProperty()
    mDATE = db.DateTimeProperty(auto_now=True)
    mDATE0 = db.DateTimeProperty(auto_now_add=True)
    mWEIGHT = db.IntegerProperty()

I want to do:

mWEIGHT = mCOUNT / mDATE0

within this for loop

    for i in range(len(UNIQUES)):                        
        C_QUERY = Rep.all()
        C_QUERY.filter("mAUTHOR =", user)
        C_QUERY.filter("mUNIQUE =", UNIQUES[i])
        C_RESULT = C_QUERY.fetch(1)                
        if C_RESULT:
            rep=C_RESULT[0]
            rep.mCOUNT+=COUNTS[i]
            # how to convert mDATE0 to integer so that I can divide:
            # rep.mWEIGHT = rep.mCOUNT / rep.mDATE0
            rep.put()
        else:
            C = COUNTS[i]
            S = UNIQUES[i]
            write_to_db(S, C)

I asked the same question in several other forums and I got good and valuable advice but I am still unable to make this code work because I am confused about (objects, instance, datetime.datetime, seconds, second ... and so on) For instance, I thought that

mWEIGHT = mCOUNT / rep.mDATE0.second

would turn mDATE0 into seconds; but it does not, it just take the second part from 2010-11-12 18:57:27.338000 ie, 27.

And

mWEIGHT = mCOUNT / mDATE0.date

gives an type mismatch error message.

I also tried

rep.mWEIGHT = rep.mCOUNT / rep.mDATE0.toordinal()

this gives a number like 734088 but all items had the same number.

See also my previous question on the same subject.

Thank you for your help.

EDIT3

This works, thanks!

if C_RESULT:
    rep = C_RESULT[0]
    rep.mCOUNT+=COUNTS[i]
    utc_tuple = rep.mDATE0.utctimetuple()
    # this is actually float not integer
    mDATE0_integer = time.mktime(utc_tuple)
    mDATE0_day = mDATE0_integer / 86400
    rep.mWEIGHT = float(rep.mCOUNT / mDATE0_day)
    rep.put()

EDIT2 @Constantin: I realized that numbers need to be floats:

>>> mCOUNT = 35
>>> div = mCOUNT / mDATE0
>>> div
0
>>> div = float(mCOUNT) / float(mDATE0)
>>> div
2.7140704010987625e-08
>>> 

Not sure how to incorporate this to the script. Any suggestions?

EDIT

@Constantin:

For the item

C_RESULT[0] = "new item"

this is the result I get.

new item: 
rep: <__main__.Rep object at 0x052186D0> 
mDATE0_integer: 1289575981 
rep.mCOUNT: 35 
rep.mWEIGHT: 0             

So

mDATE0_integer = int(time.mktime(rep.mDATE0.utctimetuple()))

works and gives the integer 1289575981 but this division

rep.mWEIGHT = rep.mCOUNT / mDATE0_integer

results in 0. Any suggestions?

Answer 1

This should do what you want:

import time
mWEIGHT = mCOUNT / time.mktime(mDATE0.utctimetuple())

See mktime.

mCOUNT / mDATE0.date fails because there is no division operator for int and date.

toordinal doesn't suit you because it operates on dates and disregards time completely.