django:ValueError need more than 1 value to unpack - django

Question

I'm using ajax and django for dynamically populate a combo box. ajax component works really fine and it parse the data to the view but int the view, when i'm using the spiting function it gives me a exception called "Value Error:need more than 1 value to unpack ". can anyone helps me to figure out the error :) :)
code:
def dropdownPopulate(request):
if request.method=='POST' :
key = request.POST['id']
else:
key=""
level, tree_id=key.split(",")
next_nodes=Structure.objects.filter(tree_id=key[tree_id]).filter(level=key[level])
context={'name':next_nodes}
return render_to_response('renderAjax.html',context)

Answer 1

This is because s.split(',') is returning list of length 1:
level, tree_id = key.split(',')
Make sure it return list of length 2:
parts = key.split(',')
if len(parts) == 2:
level, tree_id = parts
elif len(parts) == 1:
level = parts[0]
tree_id = None
else:
# do something
level = tree_id = None
pass
The apply filter like this:
next_nodes = Structure.objects.all()
if level:
next_nodes = next_nodes.filter(level=level)
if tree_id:
next_nodes = next_nodes.filter(tree_id=tree_id)

Answer 2

Probably error occurs at this line:
level, tree_id=key.split(",")
It is needed to handle the situation, when key will not have ",". Or maybe it will have more than one ",".
Look at your code:
if request.method=='POST' :
key = request.POST['id']
else:
key=""
It is possible, that key will be a blank string.
Here are examples, when error can occur:
1.
>>> key = ""
>>> level, tree_id=key.split(",")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: need more than 1 value to unpack
2.
>>> key = "a,b,c"
>>> level, tree_id=key.split(",")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: too many values to unpack
Only this will be fine (when it is only one ","):
>>> key = "a,b"
>>> level, tree_id=key.split(",")
>>>

Answer 3

You have multiple problems.
level, tree_id=key.split(",")
This will fail, as key may not have ,, so split will not return 2 values.
next_nodes=Structure.objects.filter(tree_id=key[tree_id]).filter(level=key[level])
Here you are accessing key as dict, which is incorrect as it is string.