I want to exception handle 'list index out of range.'

I am using BeautifulSoup and parsing some HTMLs.

I'm getting a certain data from each HTML (using for loop) and adding that data to a certain list.

The problem is, some of the HTMLs have different format (and they don't have the data that I want in them).

So, I was trying to use exception handling and add value null to the list (I should do this since the sequence of data is important.)

For instance, I have a code like:

soup = BeautifulSoup(links) dlist = soup.findAll('dd', 'title') # I'm trying to find content between <dd class='title'> and </dd> gotdata = dlist[1] # and what i want is the 2nd content of those newlist.append(gotdata) # and I add that to a newlist 

and some of the links don't have any <dd class='title'>, so what I want to do is add string null to the list instead.

The error appears:

list index out of range. 

What I have done tried is to add some lines like this:

if not dlist[1]: newlist.append('null') continue 

But it doesn't work out. It still shows error:

list index out of range. 

What should I do about this? Should I use exception handling? or is there any easier way?

Any suggestions? Any help would be really great!

6 Answers

Handling the exception is the way to go:

try: gotdata = dlist[1] except IndexError: gotdata = 'null' 

Of course you could also check the len() of dlist; but handling the exception is more intuitive.

You have two options; either handle the exception or test the length:

if len(dlist) > 1: newlist.append(dlist[1]) continue 

or

try: newlist.append(dlist[1]) except IndexError: pass continue 

Use the first if there often is no second item, the second if there sometimes is no second item.

A ternary will suffice. change:

gotdata = dlist[1] 

to

gotdata = dlist[1] if len(dlist) > 1 else 'null' 

this is a shorter way of expressing

if len(dlist) > 1: gotdata = dlist[1] else: gotdata = 'null' 

Taking reference of ThiefMaster♦ sometimes we get an error with value given as '\n' or null and perform for that required to handle ValueError:

Handling the exception is the way to go

try: gotdata = dlist[1] except (IndexError, ValueError): gotdata = 'null' 

For anyone interested in a shorter way:

gotdata = len(dlist)>1 and dlist[1] or 'null' 

But for best performance, I suggest using False instead of 'null', then a one line test will suffice:

gotdata = len(dlist)>1 and dlist[1] 

for i in range (1, len(list)) try: print (list[i]) except ValueError: print("Error Value.") except indexError: print("Erorr index") except : print('error ')