Django QuerySet date manipulation
I have a model storing, among other things, a timezone datetime object. I am reaching out with an Ajax call from the website to one of my views, which does the following call:
def uploads(request):
user = User.objects.get(username=request.user.get_username())
cases = Case.objects.filter(user_id=user.pk).order_by('-uploaded_on')[:5]
return JsonResponse(serializers.serialize('json', cases, fields=('col1', 'col2', 'col3', 'uploaded_on')), safe=False)
When a JSON response is received at the Front End, it gets parsed with JS and analyzed. What I would like to do here, is to modify the 'uploaded_on' column with user's timezone (which I can already access with user.timezone, currently displayed as a string e.g. 'Germany/Berlin', but can easily convert it to a necessary object with e.g. pytz package).
When I try to iterate through the QuerySet like below, the values received on the Front End do not change:
for case in cases:
case.uploaded_on.astimezone(pytz.timezone(user.timezone))
This is probably related to the fact that QuerySets are lazy, like described in Django's documentation. Can anyone suggest how this can be done?
A bonus question as well: with Django's serializer, can I pass along more than one QuerySet in a single JSON response? When I try to pack a few in a list, I get a MultiValueDictKeyError:
return JsonResponse(serializers.serialize('json', [cases, cases2]), safe=False)
python json django timezone
add a comment |
I have a model storing, among other things, a timezone datetime object. I am reaching out with an Ajax call from the website to one of my views, which does the following call:
def uploads(request):
user = User.objects.get(username=request.user.get_username())
cases = Case.objects.filter(user_id=user.pk).order_by('-uploaded_on')[:5]
return JsonResponse(serializers.serialize('json', cases, fields=('col1', 'col2', 'col3', 'uploaded_on')), safe=False)
When a JSON response is received at the Front End, it gets parsed with JS and analyzed. What I would like to do here, is to modify the 'uploaded_on' column with user's timezone (which I can already access with user.timezone, currently displayed as a string e.g. 'Germany/Berlin', but can easily convert it to a necessary object with e.g. pytz package).
When I try to iterate through the QuerySet like below, the values received on the Front End do not change:
for case in cases:
case.uploaded_on.astimezone(pytz.timezone(user.timezone))
This is probably related to the fact that QuerySets are lazy, like described in Django's documentation. Can anyone suggest how this can be done?
A bonus question as well: with Django's serializer, can I pass along more than one QuerySet in a single JSON response? When I try to pack a few in a list, I get a MultiValueDictKeyError:
return JsonResponse(serializers.serialize('json', [cases, cases2]), safe=False)
python json django timezone
add a comment |
I have a model storing, among other things, a timezone datetime object. I am reaching out with an Ajax call from the website to one of my views, which does the following call:
def uploads(request):
user = User.objects.get(username=request.user.get_username())
cases = Case.objects.filter(user_id=user.pk).order_by('-uploaded_on')[:5]
return JsonResponse(serializers.serialize('json', cases, fields=('col1', 'col2', 'col3', 'uploaded_on')), safe=False)
When a JSON response is received at the Front End, it gets parsed with JS and analyzed. What I would like to do here, is to modify the 'uploaded_on' column with user's timezone (which I can already access with user.timezone, currently displayed as a string e.g. 'Germany/Berlin', but can easily convert it to a necessary object with e.g. pytz package).
When I try to iterate through the QuerySet like below, the values received on the Front End do not change:
for case in cases:
case.uploaded_on.astimezone(pytz.timezone(user.timezone))
This is probably related to the fact that QuerySets are lazy, like described in Django's documentation. Can anyone suggest how this can be done?
A bonus question as well: with Django's serializer, can I pass along more than one QuerySet in a single JSON response? When I try to pack a few in a list, I get a MultiValueDictKeyError:
return JsonResponse(serializers.serialize('json', [cases, cases2]), safe=False)
python json django timezone
I have a model storing, among other things, a timezone datetime object. I am reaching out with an Ajax call from the website to one of my views, which does the following call:
def uploads(request):
user = User.objects.get(username=request.user.get_username())
cases = Case.objects.filter(user_id=user.pk).order_by('-uploaded_on')[:5]
return JsonResponse(serializers.serialize('json', cases, fields=('col1', 'col2', 'col3', 'uploaded_on')), safe=False)
When a JSON response is received at the Front End, it gets parsed with JS and analyzed. What I would like to do here, is to modify the 'uploaded_on' column with user's timezone (which I can already access with user.timezone, currently displayed as a string e.g. 'Germany/Berlin', but can easily convert it to a necessary object with e.g. pytz package).
When I try to iterate through the QuerySet like below, the values received on the Front End do not change:
for case in cases:
case.uploaded_on.astimezone(pytz.timezone(user.timezone))
This is probably related to the fact that QuerySets are lazy, like described in Django's documentation. Can anyone suggest how this can be done?
A bonus question as well: with Django's serializer, can I pass along more than one QuerySet in a single JSON response? When I try to pack a few in a list, I get a MultiValueDictKeyError:
return JsonResponse(serializers.serialize('json', [cases, cases2]), safe=False)
python json django timezone
python json django timezone
asked Nov 13 '18 at 23:14
Greem666Greem666
9810
9810
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
To me there would be two approaches:
Annotate the
cases
queryset with a new column, something likeuploaded_at_utz
and do timezone manipulation at database level. For example you could useTruncSecond
function to do something like the following:
cases = Case.objects.filter(user_id=user.pk).annotate(uploaded_at_utz=TruncSecond('uploaded_on', tzinfo=pytz.timezone(user.timezone)).order_by('-uploaded_on')[:5]
The other approach would be to do this at python level. For this I would go for a generator function, something like:
def convert_to_timezone(cases, tzinfo):
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(tzinfo)
yield case
Then, in you would pass convert_to_timezone(cases, pytz.timezone(user.timezone))
to your JsonResponse
constructor.
You should also explore the use of timezone.override and/or timezone.localtime although I'm not familiar with them.
add a comment |
Regarding the date manipulation, datetime.astimezone()
returns a new datetime rather than converting in-place. You'd need to assign the converted value back to case.uploaded_on
.
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(pytz.timezone(user.timezone))
Regarding whether you can pass along more than one queryset in a single JSON response, you can use itertools.chain
to do that.
from itertools import chain
return JsonResponse(serializers.serialize('json', chain(cases, cases2)), safe=False)
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53290901%2fdjango-queryset-date-manipulation%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
To me there would be two approaches:
Annotate the
cases
queryset with a new column, something likeuploaded_at_utz
and do timezone manipulation at database level. For example you could useTruncSecond
function to do something like the following:
cases = Case.objects.filter(user_id=user.pk).annotate(uploaded_at_utz=TruncSecond('uploaded_on', tzinfo=pytz.timezone(user.timezone)).order_by('-uploaded_on')[:5]
The other approach would be to do this at python level. For this I would go for a generator function, something like:
def convert_to_timezone(cases, tzinfo):
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(tzinfo)
yield case
Then, in you would pass convert_to_timezone(cases, pytz.timezone(user.timezone))
to your JsonResponse
constructor.
You should also explore the use of timezone.override and/or timezone.localtime although I'm not familiar with them.
add a comment |
To me there would be two approaches:
Annotate the
cases
queryset with a new column, something likeuploaded_at_utz
and do timezone manipulation at database level. For example you could useTruncSecond
function to do something like the following:
cases = Case.objects.filter(user_id=user.pk).annotate(uploaded_at_utz=TruncSecond('uploaded_on', tzinfo=pytz.timezone(user.timezone)).order_by('-uploaded_on')[:5]
The other approach would be to do this at python level. For this I would go for a generator function, something like:
def convert_to_timezone(cases, tzinfo):
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(tzinfo)
yield case
Then, in you would pass convert_to_timezone(cases, pytz.timezone(user.timezone))
to your JsonResponse
constructor.
You should also explore the use of timezone.override and/or timezone.localtime although I'm not familiar with them.
add a comment |
To me there would be two approaches:
Annotate the
cases
queryset with a new column, something likeuploaded_at_utz
and do timezone manipulation at database level. For example you could useTruncSecond
function to do something like the following:
cases = Case.objects.filter(user_id=user.pk).annotate(uploaded_at_utz=TruncSecond('uploaded_on', tzinfo=pytz.timezone(user.timezone)).order_by('-uploaded_on')[:5]
The other approach would be to do this at python level. For this I would go for a generator function, something like:
def convert_to_timezone(cases, tzinfo):
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(tzinfo)
yield case
Then, in you would pass convert_to_timezone(cases, pytz.timezone(user.timezone))
to your JsonResponse
constructor.
You should also explore the use of timezone.override and/or timezone.localtime although I'm not familiar with them.
To me there would be two approaches:
Annotate the
cases
queryset with a new column, something likeuploaded_at_utz
and do timezone manipulation at database level. For example you could useTruncSecond
function to do something like the following:
cases = Case.objects.filter(user_id=user.pk).annotate(uploaded_at_utz=TruncSecond('uploaded_on', tzinfo=pytz.timezone(user.timezone)).order_by('-uploaded_on')[:5]
The other approach would be to do this at python level. For this I would go for a generator function, something like:
def convert_to_timezone(cases, tzinfo):
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(tzinfo)
yield case
Then, in you would pass convert_to_timezone(cases, pytz.timezone(user.timezone))
to your JsonResponse
constructor.
You should also explore the use of timezone.override and/or timezone.localtime although I'm not familiar with them.
answered Nov 14 '18 at 0:24
ivissaniivissani
57146
57146
add a comment |
add a comment |
Regarding the date manipulation, datetime.astimezone()
returns a new datetime rather than converting in-place. You'd need to assign the converted value back to case.uploaded_on
.
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(pytz.timezone(user.timezone))
Regarding whether you can pass along more than one queryset in a single JSON response, you can use itertools.chain
to do that.
from itertools import chain
return JsonResponse(serializers.serialize('json', chain(cases, cases2)), safe=False)
add a comment |
Regarding the date manipulation, datetime.astimezone()
returns a new datetime rather than converting in-place. You'd need to assign the converted value back to case.uploaded_on
.
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(pytz.timezone(user.timezone))
Regarding whether you can pass along more than one queryset in a single JSON response, you can use itertools.chain
to do that.
from itertools import chain
return JsonResponse(serializers.serialize('json', chain(cases, cases2)), safe=False)
add a comment |
Regarding the date manipulation, datetime.astimezone()
returns a new datetime rather than converting in-place. You'd need to assign the converted value back to case.uploaded_on
.
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(pytz.timezone(user.timezone))
Regarding whether you can pass along more than one queryset in a single JSON response, you can use itertools.chain
to do that.
from itertools import chain
return JsonResponse(serializers.serialize('json', chain(cases, cases2)), safe=False)
Regarding the date manipulation, datetime.astimezone()
returns a new datetime rather than converting in-place. You'd need to assign the converted value back to case.uploaded_on
.
for case in cases:
case.uploaded_on = case.uploaded_on.astimezone(pytz.timezone(user.timezone))
Regarding whether you can pass along more than one queryset in a single JSON response, you can use itertools.chain
to do that.
from itertools import chain
return JsonResponse(serializers.serialize('json', chain(cases, cases2)), safe=False)
answered Nov 14 '18 at 13:25
Will KeelingWill Keeling
11.6k22434
11.6k22434
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53290901%2fdjango-queryset-date-manipulation%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown