I might have missed somthing while searching through the documentation - I can't seem to find a way to use data from one query to form another query.
My query is:
sites_list = Site.objects.filter(worker=worker)
I'm trying to do something like this:
for site in sites_list:
[Insert Query Here]
Edit: I saw the awnser and im not sure how i didnt get that, maybe thats the sign im up too late coding :S
You could easily do something like this:
sites_list = Site.objects.filter(worker=worker)
for site in sites_list:
new_sites_list = Site.objects.filter(name=site.name).filter(something else)
You can also use the __in lookup type. For example, if you had an Entry model with a relation to Site, you could write:
Entry.objects.filter(site__in=Site.objects.filter(...some conditions...))
This will end up doing one query in the DB (the filter condition on sites would be turned into a subquery in the WHERE clause).
Related
I am trying to search for a list of values in multiple columns in postgres (via django). I was able to use SearchQuery and SearchVector and this works great if one of the search values matches a full word. I was hoping to use icontains so that partial strings could also be used in the search. Is this possible and if so could someone point me in the right direction. Here is an example of my approach below.
Example Data:
Superhero.objects.create(
superhero='Batman',
publisher='DC Comics',
alter_ego='Bruce Wayne',
)
Superhero.objects.create(
superhero='Hulk',
publisher='Marvel Comics',
alter_ego='Bruce Banner',
)
Django filter:
from django.contrib.postgres.search import SearchQuery, SearchVector
query = SearchQuery('man') | SearchQuery('Bruce')
vector = SearchVector('superhero', 'alter_ego', 'publisher')
queryset = queryset.annotate(search=vector).filter(search=query)
This would return the Hulk record but I am hoping I can somehow use like 'icontains' so that when searching for 'man' the Batman record would also be returned. Any help is appreciated!
You can apply icontains to the filter like:
queryset = queryset.annotate(search=vector).filter(search__icontains=query)
So SearchQuery and SearchVector are a part of Django's Full Text searching functionality and it doesnt look like you can achieve what I was wanting to do with these functions. I have taken a different approach thanks to Julian Phalip's approach here.. https://www.julienphalip.com/blog/adding-search-to-a-django-site-in-a-snap/
I am little new to Django,
My Question is How do i do %LIKE% of MYSQL in Django Filter
Want something like this
myModel.objects.filter(myField__**like**="xyz")
as we can do
myModel.objects.filter(myField__startswith="xyz")
for strings that starts with 'xyz' but i want to match anywhere in the myField content.
What i know
it can be done by REGEX and .extra() but i want something very straight forward.
Thanks in advance.
You can do it like this:
myModel.objects.filter(myField__contains = "xyz")
Note: __contains is case sensitive. You can use __icontains if you don't care about the case of the text.
Use the contains operator my_model.objects.filter(my_field__contains='xyz') and icontains if you want case insensitivity
Let's say I have a list of people that can be "followed".
I'd like to iterate through all the people that a certain user is following and grab posts from all of those users in the form of a queryset.
I understand that I can combine querysets by using chain or |, but I'm a bit confused when it comes to combining querysets that I might grab from looping through everyone being followed.
following = UserFollows.objects.filter(user_id = user.id)
for follow in following.iterator():
UserPost.objects.filter(user=follow.user) #what do I do with this?
How would I combine those if I cant explicitly name them to chain or '|'?
You can do something like this:
following = UserFollows.objects.filter(user__id = user.id).select_related('user')
users_ids = [follow.user.id for follow in following]
posts = UserPost.objects.filter(user__id__in=users_ids)
but look that it is quite expensive operation so it's good to add select_related() method to fetch users in one query. I think you should also consider to cache the users_ids list before get it from database.
Have you tried something like
following = UserFollows.objects.filter(user_id = user.id)
q = UserPost.objects.filter(user=following[0].user)
for follow in following[1:]:
q = q | UserPost.objects.filter(user=follow.user)
I'm not sure the best way to describe what it is that I'm trying to do so forgive my title.
I have two models, User and Group. Group contains field, members, which is a ManyToManyField referring to User.
Given a User, I want to find all of the Groups to which that user belongs.
My idea would be to do something like this:
groups = Group.objects.filter(user in members)
Something like that. Even though I realize that this isn't right
I tried reading through this link but couldn't figure out how to apply:
http://docs.djangoproject.com/en/dev/topics/db/queries/#spanning-multi-valued-relationships
Thanks
EDIT:
Figured it out
groups = Group.objects.filter(members__username=user.username)
If you have the user and you want to have his groups then start querying from it, not the way around ;)
Here's an example:
james = User.objects.get(pk= 123)
james_groups = james.group_set.all()
The most concise way is probably
groups = user1.group_set.all()
which gives you a queryset that is iterable.
I have two simple models: Book, and Author
Each Book has one Author, linked through a foreignkey.
Things work normally until I try to use defer/only on an annotation:
authors=Author.objects.all().annotate(bookcount=Count('books'))
that works. The query looks like:
select table_author.name, table_author.birthday, COUNT(table_book.id) as bookcount
from table_book left outer join table_author on table_author.id=table_book.author_id
group by table_author.id
so very simple - selecting everything from author, and additionally selecting a count of the books.
But when I do the following, everything changes:
simple=authors.defer('birthday')
now, the simple query looks like this:
select COUNT(table_book.id) as bookcount from table_book left outer join
table_author on table_author.id=table_book.author_id group by table_author.id
and it has completely lost the extra information. What's the deal?
Well, this would seem to be a bug. There's already a ticket, but it hasn't had much attention for a while. Might be worth making a post to the django-developers Google group to chivvy things along.