On Saturday, September 27, 2014 9:06:58 PM UTC+8, aRkadeFR wrote:
>
> @James Brewer:
> If I change my code, I can have this user_ids list.
> btw, it's filter and not get if you're searching multiple objects (the
> user_ids).
>
> @Alejandro Varas G.:
> That doesn't change the fact that 'User.objects.get(id=X)' will hit the
> database everytime.
>
> Right now, the problem is solved, by creating the AllUserSet, but I think
> my
> code is pretty ugly, and it seems strange to me that the ORM can't handle
> that
> built-in, by caching the .all() or .filter(id__in=users_ids)
>
>
Django actually caches all objects fetched when it evaluates .all or
.filter method. The problem you are facing is that how to reuse the cached
objects efficiently to avoid hitting database with unnecessary SQL queries.
James gave you a good solution. Based on his solution, you don't need to
call the `get' method each time getting user by id. Just iterate users
object and find the right one by comparing id.
> The ideally solution would be something like:
>
> AllUser = User.objects.all()
>
> for i in user_id:
> AllUser.get(id=i)
>
>
This piece of code would be changed to
AllUser = User.objects.all()
for i in user_id:
for user in AllUser:
if user.pk == i:
print 'find the user'
or, even you may construct AllUser to dict to simplify the search
AllUser = dict((user.pk, user) for user in User.objects.all()) # Here, hit
db, only once
for i in user_id:
user = AllUser.get(i, None) # search by id in memory
if user is not None:
print 'find the user'
Hope, this could help you.
But this code hits the database every time the 'get' is called.
>
>
> On 26/09/14 12:36, James Brewer wrote:
> > Do you have a single list of the IDs you want? If so, you can do
> something
> > like `User.objects.get(id__in=user_ids)`. This will fetch all Users
> whose
> > `id` is in some list `user_ids`.
> >
> > Does that help?
> >
> > Happy hacking!
> >
> > James
> >
> > On Fri, Sep 26, 2014 at 11:43 AM, Alejandro Varas G. <[email protected]
> <javascript:>>
> > wrote:
> >
> > > Hi,
> > >
> > > You should use User.objects.get(id=X)
> > >
> > > Best
> > > El 26/09/2014 15:28, "aRkadeFR" <[email protected] <javascript:>>
> escribió:
> > >
> > > >
> > > > Hey!
> > > >
> > > > I'm having a hard time trying to reduce the number of SQL queries on
> a
> > > view.
> > > >
> > > > Basically, I'm fetching all my User, with User.objects.all(), and
> save
> > > this
> > > > queryset as AllUser.
> > > >
> > > > Then every time I need to get the user with the id = X , I'm calling
> a
> > > function
> > > > 'get_user_from_id', that iterate over the AllUser queryset variable,
> and
> > > when
> > > > it finds the id, returns it.
> > > >
> > > > I considerably reduced the number of SQL queries, but I would like
> to
> > > know if
> > > > you think of a better way?
> > > >
> > > > Thank you
> > > >
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> > > <
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> >
> >
> >
> > --
> > James Brewer
> > jamesbrewer.io
> >
> > --
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