If I use the values() or values_list() the request in database has a long
waiting time and some time I also got a MemoryError (because 4GB RAM is not
enough).
My examples:
Apple.objects.select_related('Orange').filter(state='fresh').values_list(
# Fields I don't want:
'field1',
'field2',
'field3'
# ..... ,
'field37'
)
( yes I want 37 different values ).
I also try with .only() with very nice response time, but in the end I will get
all the fields. For example:
temp = Apple.objects.select_related('Orange').filter(state='fresh').only(
'field1',
'field2',
'field3' )
temp_json = serializers.serialize('json', temp)
return HttpResponse(temp_json, content_type='application/json')
it returns me all the fields! Not only the 'field2', 'field2' and 'field3'.
Could you explain me why ?
Finally, I also tried to run a query with raw() but the response time is
disappointing.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, May 28, 2021 2:13 AM, David Nugent <[email protected]> wrote:
> I think a better approach to using QuerySet.defer() is to use .values()
> instead, explicitly specifying which fields you need to export.
>
> Just FYI rest_framework handles this out of the box and provides an API to
> specify not only which fields to export but filters as well.
>
> Regards
> /d
>
> On Fri, May 28, 2021 at 8:10 AM 'odrzen' via Django users
> <[email protected]> wrote:
>
>> Hello Django community o/
>>
>> I want to create a API call in order to get all data from a specific model (
>> table ) - but I want to exclude-remove only specific fields from this.
>> So, I try to find a right way to execute this difficult and "heavy"
>> query/request with a efficient way.
>> This is what I have achieved so far:
>>
>> ```
>> #from django.http import HttpResponse, HttpResponseRedirect, JsonResponse
>> #from django.core import serializers
>> from apples.models import Apple
>> from oranges.models import Orange
>>
>> published_fruits =
>> Apple.objects.select_related('Orange').filter(state='published').defer(
>> # Fields I don't want:
>> 'field1',
>> 'field2',
>> 'field3'
>> )
>>
>> So, I have the following results:
>> [
>> {
>> "model": "apples.apple",
>> "pk": "5326t236-8415-48f4-89e5-1789vc9of442",
>> "fields": {
>> "id": "apple-type1",
>> "name": "Brazil",
>> ".....": "....",
>> "exports ": []
>> }
>> },
>> { ... }
>> {
>> "model": "apples.apple",
>> "pk": "6435673472-fret2-523t-523t-d41159t23432213",
>> "fields": {
>> "id": "apple-type2",
>> "name": "India",
>> ".....": "....",
>> "exports ": []
>> }
>> }
>> ]
>> ```
>>
>> My proble is :
>> 1. The fields who I don't want (exclude), finally I got it.
>> 2. I want to directly pass all this response to a JSON http output for the
>> users and I have it with the following way:
>> ```
>> json_response = serializers.serialize('json', published_fruits)
>> return HttpResponse(json_response, content_type='application/json')
>> ```
>> I get all the respone in JSON, but ( as you can see above ) with the
>> following stracture:
>> ```
>> {
>> "model": "apples.apple",
>> "pk": "6435673472-fret2-523t-523t-d41159t23432213",
>> "fields": {
>> "id": "apple-type2",
>> "name": "India",
>> ".....": "....",
>> "exports ": []
>> }
>> }
>> ```
>>
>> Please, could you help me to avoid the following part from each record :
>> ```
>> "model": "apples.apple",
>> "pk": "6435673472-fret2-523t-523t-d41159t23432213",
>> "fields": {
>> ```
>> from the JSON ?
>>
>> Thank you very much in advance!
>>
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