unable to assign values to variables in python

Question

I am trying to pull datastore values from vcenter and perform usage calculations as below:

s = VIServer()
s.connect(HOST, USER, PASSWORD)


properties = [  "name",
                "summary.capacity",
                "summary.freeSpace",
             ]

results = s._retrieve_properties_traversal(property_names=properties,
                                           obj_type=MORTypes.Datastore)
d = time.strftime('%Y-%m-%d %H:%M:%S')

for item in results:
    for r in item.PropSet:
                if r.Name == "name" :
                        name = r.Val

    for p in item.PropSet:
        global Total_Space,Free_Space
        if p.Name=="summary.capacity":
                Total_Space=p.Val
                Metric="datastore.space_total"
                print Metric,d,p.Val,"datastore="+name,"source="+"datastore"

        if p.Name=="summary.freeSpace":
                Free_Space=p.Val
                Metric="datastore.space_free"
                print Metric,d,p.Val,"datastore="+name,"source="+"datastore"
        if Total_Space>0 &  Free_Space>0:
                Used_Space=Total_Space-Free_Space
                Used_Percent=(Used_Space/Total_Space)*100

                Metric="datastore.space_used"
                print Metric,d,Used_Space,"datastore="+name,"source="+"datastore"
                Metric="datastore.diskPctUsed"
                print Metric,d,Used_Percent,"datastore="+name,"source="+"datastore"

When I run this I get this error:

Traceback (most recent call last):
  File "datastore.py", line 41, in <module>
    if Total_Space>0 &  Free_Space>0:
NameError: global name 'Total_Space' is not defined

Any ideas how I could fix this?

Not directly related to your problem: You should change the & to and. & does something entirely different. — Kevin
– Kevin, Commented Nov 25, 2014 at 21:31
Looks like you could get to line 41 without ever assigning a value to Total_Space. — Surreal Dreams
– Surreal Dreams, Commented Nov 25, 2014 at 21:33

pmod · Accepted Answer · 2014-11-26 08:43:54Z

1

From code logic it makes sense to check these values after for loop. Thus, you will make sure that they are initialized and checked once:

 ...
 Total_Space = 0
 Free_Space = 0
 for p in item.PropSet:
     ...

 if Total_Space and Free_Space:
     ...

However, if you'd initialize them to None, you can have additional check for presence them in PropSet :

 ...
 Total_Space = None
 Free_Space = None
 for p in item.PropSet:
     ...

 if Total_Space == None:
     print "error: no Total_Space in PropSet"
 elif Free_Space == None:
     print "error: no Free_Space in PropSet"
 elif Total_Space and Free_Space:
     ...

Some notes:

You should use and boolean operator instead of & for bitwise operator
Moreover, & has higher priority than > and expression will be evaluated as

if Total_Space > (0 & Free_Space) > 0:
In conditionals, you can use just if value instead of if value>0

edited Nov 26, 2014 at 8:43

answered Nov 25, 2014 at 21:51

pmod

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4 Comments

user1471980 Over a year ago

thank you for the answer. I am getting space_total, space_free but not used_space and used_percent, it looks like the last if statment is not processing.

pmod Over a year ago

@user1471980 but do you see these properties when you reading p.Val? Just to make sure you really receive/read these property values as zeroes?

user1471980 Over a year ago

I do see the values as here:datastore.space_total 2014-11-25 17:41:04 2684354560000 datastore=NFS13 source=datastore datastore.space_free 2014-11-25 17:41:04 1781300174848 datastore=NFS13 source=datastore

pmod Over a year ago

@user1471980 "if Total_Space and Free_Space:" should work (not &)

ChesterL · Accepted Answer · 2014-11-25 21:33:39Z

1

Because you did not declare 'Total_Space' globally before say global Total_Space, your should add Total_Space = None # or whatever value you like globally, i.e. outside of for loop or any function

answered Nov 25, 2014 at 21:33

ChesterL

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Comments

Hasan Ramezani · Accepted Answer · 2014-11-25 21:54:11Z

1

initialize Total_Space and Free_Space with a value in first of your program.

Total_Space = 0
Free_Space = 0

edited Nov 25, 2014 at 21:54

answered Nov 25, 2014 at 21:31

Hasan Ramezani

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