I have an error message on django 1.4:
dictionary update sequence element #0 has length 1; 2 is required
[EDIT]
It happened when I tried using a template tag like: `{% for v in values %}:
dictionary update sequence element #0 has length 1; 2 is required
Request Method: GET
Request URL: ...
Django Version: 1.4.5
Exception Type: ValueError
Exception Value:
dictionary update sequence element #0 has length 1; 2 is required
Exception Location: /usr/local/lib/python2.7/dist-packages/djorm_hstore/fields.py in __init__, line 21
Python Executable: /usr/bin/uwsgi-core
Python Version: 2.7.3
Python Path:
['/var/www/',
'.',
'',
'/usr/lib/python2.7',
'/usr/lib/python2.7/plat-linux2',
'/usr/lib/python2.7/lib-tk',
'/usr/lib/python2.7/lib-old',
'/usr/lib/python2.7/lib-dynload',
'/usr/local/lib/python2.7/dist-packages',
'/usr/lib/python2.7/dist-packages',
'/usr/lib/python2.7/dist-packages/PIL',
'/usr/lib/pymodules/python2.7']
Server time: sam, 13 Jul 2013 16:15:45 +0200
Error during template rendering
In template /var/www/templates/app/index.html, error at line 172
dictionary update sequence element #0 has length 1; 2 is required
172 {% for product in products %}
Traceback Switch to copy-and-paste view
/usr/lib/python2.7/dist-packages/django/core/handlers/base.py in get_response
response = callback(request, *callback_args, **callback_kwargs)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/contrib/auth/decorators.py in _wrapped_view
return view_func(request, *args, **kwargs)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/views/decorators/http.py in inner
return func(request, *args, **kwargs)
...
? Local vars
./app/views.py in index
context_instance=RequestContext(request))
...
? Local vars
/usr/lib/python2.7/dist-packages/django/shortcuts/__init__.py in render_to_response
return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/loader.py in render_to_string
return t.render(context_instance)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/base.py in render
return self._render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/base.py in _render
return self.nodelist.render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/base.py in render
bit = self.render_node(node, context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/debug.py in render_node
return node.render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/loader_tags.py in render
return compiled_parent._render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/base.py in _render
return self.nodelist.render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/base.py in render
bit = self.render_node(node, context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/debug.py in render_node
return node.render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/loader_tags.py in render
result = block.nodelist.render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/base.py in render
bit = self.render_node(node, context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/debug.py in render_node
return node.render(context)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/template/defaulttags.py in render
len_values = len(values)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/core/paginator.py in __len__
return len(self.object_list)
...
? Local vars
/usr/lib/python2.7/dist-packages/django/db/models/query.py in __len__
self._result_cache = list(self.iterator())
...
? Local vars
/usr/lib/python2.7/dist-packages/django/db/models/query.py in iterator
obj = model(*row[index_start:aggregate_start])
...
? Local vars
/usr/lib/python2.7/dist-packages/django/db/models/base.py in __init__
setattr(self, field.attname, val)
...
? Local vars
/usr/local/lib/python2.7/dist-packages/djorm_hstore/fields.py in __set__
value = self.field._attribute_class(value, self.field, obj)
...
? Local vars
/usr/local/lib/python2.7/dist-packages/djorm_hstore/fields.py in __init__
super(HStoreDictionary, self).__init__(value, **params)
...
? Local vars
It happens too when I try to access on a hstore queryset:
[edit]
Traceback (most recent call last):
File "manage.py", line 14, in <module>
execute_manager(settings)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 459, in execute_manager
utility.execute()
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 382, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 196, in run_from_argv
self.execute(*args, **options.__dict__)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 232, in execute
output = self.handle(*args, **options)
File "/home/name/workspace/project/app/data/commands/my_command.py", line 60, in handle
item_id = tmp[0].id,
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 207, in __getitem__
return list(qs)[0]
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 87, in __len__
self._result_cache.extend(self._iter)
File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 301, in iterator
obj = model(*row[index_start:aggregate_start])
File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 300, in __init__
setattr(self, field.attname, val)
File "/usr/local/lib/python2.7/dist-packages/djorm_hstore/fields.py", line 38, in __set__
value = self.field._attribute_class(value, self.field, obj)
File "/usr/local/lib/python2.7/dist-packages/djorm_hstore/fields.py", line 21, in __init__
super(HStoreDictionary, self).__init__(value, **params)
ValueError: dictionary update sequence element #0 has length 1; 2 is required
the code is:
tmp = Item.objects.where(HE("kv").contains({'key':value}))
if tmp.count() > 0:
item_id = tmp[0].id,
I'm just trying to access the value. I don't understand the "update sequence" message. When I use a cursor instead of hstore queryset, the function works. The error comes on template rendering too. I just restarted uwsgi and everything works well, but the error comes back later.
[edit]
Has someone an idea?
Here is how I encountered this error in Django and fixed it:
urlpatterns = [path('home/', views.home, 'home'),]
urlpatterns = [path('home/', views.home, name='home'),]
I hit this error calling:
dict(my_data)
I fixed this with:
import json
json.loads(my_data)
I got the same issue and found that it was due to wrong parameters.
In views.py, I used:
return render(request, 'demo.html',{'items', items})
But I found the issue: {'items', items}. Changing to {'items': items} resolved the issue.
I encountered this issue when trying to invoke the update method with a parameter of a wrong type. The expected dict was:
{'foo': True}
The one that was passed was:
{'foo': "True"}
make sure you check all the parameters you pass are of the expected type.
Pass a keyword argument name with value as your view name e.g home or home-view etc. to url() function.
url(r'^home$', 'common.views.view1', 'home'),
url(r'^home$', 'common.views.view1', name='home'),
Just ran into this problem. I don't know if it's the same thing that hit your code, but for me the root cause was because I forgot to put name= on the last argument of the url (or path in Django 2.0+) function call.
For instance, the following functions throw the error from the question:
url(r'^foo/(?P<bar>[A-Za-z]+)/$', views.FooBar.as_view(), 'foo')
path('foo/{slug:bar}/', views.FooBar, 'foo')
But these actually work:
url(r'^foo/(?P<bar>[A-Za-z]+)/$', views.FooBar.as_view(), name='foo')
path('foo/{slug:bar}/', views.FooBar, name='foo')
The reason why the traceback is unhelpful is because internally, Django wants to parse the given positional argument as the keyword argument kwargs, and since a string is an iterable, an atypical code path begins to unfold. Always use name= on your urls!
I faced the above mentioned problem when I forgot to pass a keyword argument name to url() function.
Code with error
url(r"^testing/$", views.testing, "testing")
Code without error
url(r"^testing/$", views.testing, name="testing")
So finally I removed the above error in this way. It might be something different in your case. So check your url patterns in urls.py.
I got this error when I was messing around with string and dictionary.
dict1 = {'taras': 'vaskiv', 'iruna': 'vaskiv'}
str1 = str(dict1)
dict(str1)
*** ValueError: dictionary update sequence element #0 has length 1; 2 is required
So what you actually got to do to get dict from string is:
dic2 = eval(str1)
dic2
{'taras': 'vaskiv', 'iruna': 'vaskiv'}
Or in matter of security we can use literal_eval
from ast import literal_eval
You are sending one parameter incorrectly; it should be a dictionary object:
Wrong: func(a=r)
Correct: func(a={'x':y})
In my case, my get_context_data in one of my views was returning return render(self.request, 'es_connection_error.html', {'error':error}); in a try/catch block instead of returning context
The error should be with the params. Please verify that the params is a dictionary object. If it is just a list/tuple of arguments use only one * (*params) instead of two * (**params). This will explode the list/tuple into the proper amount of arguments.
Or, if the params is coming from some other part of code as a JSON file, please do json.loads(params), because the JSON objects sometimes behave as string and so you need to make it as a JSON using load from string (loads).
super(HStoreDictionary, self).__init__(value, **params)
Hope this helps!
I too had a similar type of problem . The solution is simple . just dont try to enter NULL or None value in values or u might have to use Something like thisdic.update([(key,value)])
Here is the reproduced error.
>>> d = {}
>>> d.update([(1,)])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: dictionary update sequence element #0 has length 1; 2 is required
>>>
>>> d
{}
>>>
>>> d.update([(1, 2)])
>>> d
{1: 2}
>>>
>>> d.update('hello_some_string')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: dictionary update sequence element #0 has length 1; 2 is required
>>>
If you give the sequence and any element length is 1 and required two then we will get this kind of error. See the above code. First time I gave the sequence with tuple and it's length 1, then we got the error and dictionary is not updated. second time I gave inside tuple with with two elements, dictionary got updated.
Error in your question is raised when you try something like following:
>>> a_dictionary = {}
>>> a_dictionary.update([[1]])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: dictionary update sequence element #0 has length 1; 2 is required
It's hard to tell where is the cause in your code unless you show your code, full traceback.
Source: Stackoverflow.com