CODEWITHSUNDEEP
pythoncsvtypeerror
Rasnaam Tiwana
Rasnaam Tiwana

Reputation: 67

TypeError: object of type 'NoneType' has no len() python

I keep getting this error 

TypeError: object of type 'NoneType' has no len()

here is the code:

def main():
    myList = [ ]
    myList = read_csv()
    ## myList = showList(myList)
    searchList = searchQueryForm(myList)
    if len(searchList) == 0:
        print("I have nothing to print")
    else:
        showList(searchList)

Upvotes: 3

Views: 30110

Answers (3)

Vivek Sable
Vivek Sable

Reputation: 10223

The searchQueryForm() function return None value and len() in-build function not accept None type argument. So Raise TypeError exception.

Demo:

>>> searchList = None
>>> print type(searchList)
<type 'NoneType'>
>>> len(searchList)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
TypeError: object of type 'NoneType' has no len()

Add one more condition in if loop to check searchList is None or not

Demo:

>>> if searchList==None or len(searchList) == 0:
...   print "nNothing"
... 
nNothing

return statement is missing in the searchQueryForm() function when code is not go into last if loop. By default None value is return when we not return any specific value from function.

def searchQueryForm(alist):
    noforms = int(input(" how many forms do you want to search for? "))
    for i in range(noforms):
        searchQuery = [ ]
        nofound = 0 ## no found set at 0
        formname = input("pls enter a formname >> ") ## asks user for formname
        formname = formname.lower() ## converts to lower case
        for row in alist:
            if row[1].lower() == formname: ## formname appears in row2
                searchQuery.append(row) ## appends results
                nofound = nofound + 1 ## increments variable
                if nofound == 0:
                    print("there were no matches")
                    return searchQuery
    return []
   # ^^^^^^^    This was missing

Upvotes: 0

glglgl
glglgl

Reputation: 91119

The object which you want to get the len() from is obviously a None object.

It is the searchList, returned from searchQueryForm(myList).

So this is None when it shouldn't be.

Either fix that function or live with the fact that it can return None:

if len(searchlist or ()) == 0:

or 

if not searchlist:

Upvotes: 2

Mureinik
Mureinik

Reputation: 311883

searchQueryForm apparently returns a None if it finds nothing. Since you can't apply len to None, you'll have to check for that explicitly:

if searchList is None or len(searchList) == 0:

Upvotes: 7

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