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Building simlpe django firehose

I have an app that I want to build a "recent activity"/firehose feed of 2-3 combined types of activity such as posts, comments, and likes of posts, and something else + maybe more later. I assume this is done with a query of taking the last of the appropriate object added to the DB and combining it with the last of the other type of object and ordering the new combined list of objects by their timestamps. What is the best way to do something like this? For now, I have something like this for every time someone refreshes the page:
NewPost.objects.all().order_by('-postdate')[0:10] #takes the last 16 recently added posts
Comment.objects.all().order_by('-commentdate')[0:10] #takes equal number of comments site wide ordered by timestamp
So what is the best way to take both of these querysets and render the different Models in 1 list ordered by their timestamp? I assume the type of logic will be the same for adding additional types of objects, so I just want to know how to do it with just 2. Thanks!

I don't really like your approach since when you want to put another object on the firehose you'd need to add a third line (AnotherObject.objects.all ... etc ) to all places you need to display that firehose !
For me, the best way to do this is to create a Firehose Model with fields like: date, action (add/delete/update etc) and object (a generic Foreign Key to the object that was changed). Now, whenever you make a change to an object that you want to add to the firehose, you'd add a new instance of the FirehoseClass with the correct field values. Finally, whenever you want to display the firehose you'll just display all firehose objects.

To combine the lists, you can use create a list by using chain() from itertools, and then sort them by using sorted():
from itertools import chain
combined_lists = list(chain(new_post_list, comment_list))
sorted_combinened_list = sorted(combined_list, key=lambda instance: instance.postdate)
However, as you see, the sorting is only done by using one key. I don't know of any method to use two different keys when sorting. You could fix this by simply add a property to the Comment class, named postdate that simply returns commentdate. Or, even better, you should use the same name for creation time for all your models, e.g. created_at.
This has been answered earlier and more detailed here: How to combine 2 or more querysets in a Django view?

Django conditionally excluding fields

I am new to Django and am having some trouble with filtering. Please excuse the contrived example. I have some model for events, with a one to many relationship with attendees. From my set of events I want to exclude events occurring in Boston, but only if there's only 1 attendee. The code below is what I've tried that definitely does not work:
queryset = queryset.annotate(attendees_count=Count('attendees')).exclude(attendees_count=1, event_location__city="Boston")
I don't get an error. Rather it just filters out "Boston" regardless of "attendees_count".
In addition to a query that actually does what I want it to do, I'd like to understand why what I did doesn't work. Thanks in advance.

Are you sure that your original queryset includes Boston with >1 attendee?
https://docs.djangoproject.com/en/dev/ref/models/querysets/#django.db.models.query.QuerySet.exclude
Multiple parameters are joined via AND in the underlying SQL
statement, and the whole thing is enclosed in a NOT()

haystack solr search ALL fields

I have a solr search engine set up with multiple fields and I want to be able to search ALL fields.
I can do a .filter(content='string') but this only searches whatever fields are in the document=True
EDIT
Also, some of the non document=True fields have different filters/tokenisers applied so im guessing that would not work with adding them into a single field...

Maybe you can make a second field with 'use_template' and a template displaying ALL fields.
I never tried to do this, but this sound a good way to do it to me.
EDIT since OP comment:
Then my best bet is to eaither sublass SearchQueryset to add a method or to create a function that will loop and all fields in your SearchIndex and do something like:
qs = SearchQuerySet().filter(content=query)
for field in fieldlist:
qs = qs.filter_or(**{'field':query})
I have no idea if this works at all but that's worth trying.

#neolaser: I think what you want can be achieved by using DisMax search. It allows searching through multiple fields and specify the boost value for each of them. For more details:
http://wiki.apache.org/solr/SolrRelevancyFAQ
http://wiki.apache.org/solr/DisMaxQParserPlugin

You can search all the fields buy including them all into your filtering query parameter or by naming them in the query string (e.g. if you need to search for "keyword" search for "((field_1:keyword) OR (field_2:keyword) OR (field_3: keyword))" instead).
However, it is usually better to have a dedicated field concatenating all the others you need to search and search this single field. You can set up a copyfield in your schema to have that content generated automatically when your document is indexed.

Checking for group membership (Many to Many in Django)

I have two models in Django: groups and entries. Groups has a many-to-many field that connects it to entries. I want to select all entries that have a group (as not all do!) and be able to access their group.title field.
I've tried something along the lines of:
t = Entries.objects.select_related().exclude(group=None)
and while this returns all entries that have groups, I can't do t[0].groups to get the title. Any ideas on how this could be done?
Edit: more info
When ever I use Django's shell to inspect what is returned in t (in this example), t[0].group does not exist. The only way I can access this is via t[0].group_set.all()[0].title, which seems inefficient and like I'm doing something incorrectly.

You don't show the model code, so I can't be sure, but instead of t[0].groups, I think you want:
for g in t[0].groups.all():
print g.title

Dealing with URLs in Django

So, basically what I'm trying to do is a hockey pool application, and there are a ton of ways I should be able to filter to view the data. For example, filter by free agent, goals, assists, position, etc.
I'm planning on doing this with a bunch of query strings, but I'm not sure what the best approach would be to pass along the these query strings. Lets say I wanted to be on page 2 (as I'm using pagination for splitting the pages), sort by goals, and only show forwards, I would have the following query set:
?page=2&sort=g&position=f
But if I was on that page, and it was showing me all this corresponding info, if I was to click say, points instead of goals, I would still want all my other filters in tact, so like this:
?page=2&sort=p&position=f
Since HTTP is stateless, I'm having trouble on what the best approach to this would be.. If anyone has some good ideas they would be much appreciated, thanks ;)
Shawn J

Firstly, think about whether you really want to save all the parameters each time. In the example you give, you change the sort order but preserve the page number. Does this really make sense, considering you will now have different elements on that page. Even more, if you change the filters, the currently selected page number might not even exist.
Anyway, assuming that is what you want, you don't need to worry about state or cookies or any of that, seeing as all the information you need is already in the GET parameters. All you need to do is to replace one of these parameters as required, then re-encode the string. Easy to do in a template tag, since GET parameters are stored as a QueryDict which is basically just a dictionary.
Something like (untested):
#register.simple_tag
def url_with_changed_parameter(request, param, value):
params = request.GET
request[param] = value
return "%s?%s" % (request.path, params.urlencode())
and you would use it in your template:
{% url_with_changed_parameter request "page" 2 %}

Have you looked at django-filter? It's really awesome.

Check out filter mechanism in the admin application, it includes dealing with dynamically constructed URLs with filter information supplied in the query string.
In addition - consider saving actual state information in cookies/sessions.

If You want to save all the "parameters", I'd say they are resource identifiers and should normally be the part of URI.