I think it's simple but I cannot find the solution.
I want to get last element from the database. And create some endpoint for my rest.
I have some working solution:
views.py
class LastElementViewSet(viewsets.ModelViewSet):
serializer_class = ElementSerializer
# here I got the model Element type. So I can use it to get last_unix:
last_unix = Element.objects.last().unix
# and use it (last_unix) to get last element (Queryset type):
queryset = Element.objects.filter(unix=last_unix)
But I'm pretty sure that Django provides some better solution :D
Do you have any idea how to do something like this?
Best regards!
Related
I'm learning about Django tables. I first wrote a basic example, here my view:
def people1(request):
table = PersonTable(Person.objects.filter(id=2))
RequestConfig(request).configure(table)
return render(request, 'people.html', {'table': table})
This way I've been able to easily display a table with a filter condition "filter(id=2))".
After that I found SingleTableView which is supposed to be an easier way to display database tables, as an example I wrote this view, which worked fine:
from django_tables2 import SingleTableView
class PersonList(SingleTableView):
template_name = 'ta07/comun.html'
model = Person
table_class = PersonTable
Questions are: how should I do to apply filters like in the first example? And is SingleTableView better than the basic way?
I'd say for now, you should only use it for the very basic use case. As soon as you need customizations from that, use your own.
Since filtering is a very common use case, I might consider adding that to the features of SingleTableView at some point. If you need it before that, feel free to open a pull request.
I have searched enough of the examples but couldn't get the satisfactory result. Please explain with all the necessary code. I am very poor at AJAX. I tried to use DAJAXICE in my code and got little success but didn't work with passing parameters.
I am using Django 1.6 Dajaxice 0.7 Dajax 0.9.
Any way you feel the easiest is okay but please explain with all the code.
TIA.
If all you need is a simple Django view to fetch some data with AJAX, take a look at django-braces AjaxResponseMixin. Below is a code sample which returns list of objects ids and their names:
from django.views.generic import View
from braces import views
class SomeView(views.JSONResponseMixin, views.AjaxResponseMixin, View):
def get_ajax(self, request, *args, **kwargs):
my_objects = MyObject.objects.all()
json_dict = {
'ids': [x.id for x in my_objects],
'names': [x.name for x in my_objects]
}
return self.render_json_response(json_dict)
Then use jQuery ajax to make the query from your template and populate your fields.
If you're not familiar with Class Based Views, your url for this view could be:
url('^objects/(?P<some_id>[0-9]+)/$', SomeView.as_view())
then in get_ajax you can access self.kwargs['some_id'] to filter objects.
I'm wondering if there is a clean way to retrieve an object from its URL with django rest framework. Surely there should be, as it seems to be what's happening when using HyperlinkedRelatedField.
For instance, I have this URL /api/comment/26 as a string. From my view, how can I get the comment instance with pk=26?
Of course I could redo the work and work on the string but it must be a better way?
Thanks a lot.
EDIT:
This is how I solved it at the end:
resolve('/api/comment/26/').func.cls.model will return my model Comment.
resolve('/api/category/1/').kwargs['pk'] will return the pk.
Which gives you:
from django.core.urlresolvers import resolve
resolved_func, unused_args, resolved_kwargs = resolve('/api/category/1/')
resolved_func.cls.model.objects.get(pk=resolved_kwargs['pk'])
I suspect your best bet would be to manually keep a map of models to url patterns — not too dissimilar from a URLConf.
If that doesn't rock your boat you could pass the path into resolve.
This will give you a ResolverMatch upon which you'll find the func that was returned by the as_view call when you set up your URLs.
The __name__ attribute of your view function will be that of your original view class. Do something like globals()[class_name] to get the class itself.
From there access the model attribute.
I hope that helps. As I say, you might just want to map models to URLs yourself.
With class-based views, something like the following seems needed:
resolve(url).func.cls.serializer_class.Meta.model.objects.get(
**resolve(url).kwargs)
Solution above did not work for me, the following did work though:
from django.core.urlresolvers import resolve
resolved_func, unused_args, resolved_kwargs = resolve('/api/category/1/')
resolved_func.cls().get_queryset().get(id=resolved_kwargs['pk'])
additionally this solution uses the built in queryset of your view, which might have annotations or important filters.
Using HyperlinkedModelSerializer I actually needed to do this with a full url. For this to work, you need to extract the path first, resulting in:
import urllib.parse
from django.core.urlresolvers import resolve
def obj_from_url(url):
path = urllib.parse.urlparse(url).path
resolved_func, unused_args, resolved_kwargs = resolve(path)
return resolved_func.cls().get_queryset().get(id=resolved_kwargs['pk'])
I'm creating a formset, but it seems to populate it with all of the existing data in the table for that object. I can't figure out how to start with a blank formset; the only way seems to be to delete all of the data from the table, but clearly this isn't an option.
I will post code if necessary (but there's lots of it, so knowing what is relevant is tricky).
give a parameter queryset=Model.objects.none() when making the object.
Following Arihant's answer, I did something like this, which works:
class TagCreateFormSet(BaseModelFormSet):
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
queryset=None, **kwargs):
queryset = Tag.objects.none()
super(TagCreateFormSet, self).__init__(data, files,
auto_id, prefix, queryset, **kwargs)
It seems that it isn't possible to change the behaviour of model formset. So as a solution, I changed the data structure so that the data I want to edit is grouped by another type, and then instead I have used inlineformset_factory.
Not even sure I'm stating the question correctly. Here's the situation. I have a queryset generated by accessing the foreign key relationship. Using the standard Blog/Entry models in the Django documentation, let's say I have selected a blog and now have a set of entries:
entries = Blog.objects.get(id=1).entry_set.all()
So we have some entries for the blog, possibly zero. I'd like to then say construct a calendar and indicate which days have blog entries. So my thinking is to iterate over list of days in the month or whatever, and check the entries queryset for an entry with that date. Question is, what is the best way to do this? My first thought was to do something like
dayinfo = [] # we will iterate over this in the template
for curday in month:
dayinfo.append({'day':curday, 'entry':entries.filter(day=curday)})
Problem is that the filter call returns a new queryset, and that generates a new sql call for each loop iteration. I just need to pluck the entry object from entries if it exists and stick it into my calendar. So what is the best way to do this? I did get this to work:
dayinfo.append({'day':day, 'entry':[e for e in entries if e.day == curday][0]})
That does not generate new sql calls. But it sure seems ugly.
Resist the urge to put everything on one line - I think the code would be cleaner with something like this:
from collections import defaultdict
calendar = defaultdict(list)
for entry in entries:
calendar[entry.day].append(entry)
The defaultdict part is simple but you might want to initialize it with all of the days in a month if you're just planning to use a for loop in the template. Also note that if you're using Django 1.1 you can use the new annotate() method to simply calculate the post count if you're not actually planning to generate links to individual posts.