date:20200528

Re: Optimized Query

2020-05-28 Thread אורי

Hi Soumen,

Sometimes prefetch_related is much faster and more efficient than
select_related. I usually prefer to use prefetch_related.

Uri.
אורי
u...@speedy.net


On Thu, May 28, 2020 at 12:42 AM Soumen Khatua 
wrote:

> Actually I want to fetch all users from User table and users location from
> Location table which is many to many relation from same Profile table. Is
> it possible???
>
> On Thu 28 May, 2020, 2:54 AM Soumen Khatua, 
> wrote:
>
>> Now I'm facing one problem whenever I'm trying to iterate a loop I'm
>> getting too many SQL variables. Actually after iterating the loop I want to
>> render all the value in the template.
>> if could you resolve this it would be very good for me.
>> Thank you for your time and response
>>
>> Regards,
>> Soumen
>>
>>
>> On Thu, May 28, 2020 at 2:12 AM Chetan Ganji 
>> wrote:
>>
>>>
>>> Profile.objects.filter().select_related("user").prefetch_related("location")
>>>
>>> On Thu, May 28, 2020, 2:01 AM Soumen Khatua 
>>> wrote:
>>>
 I also know about this concept but I don't how I can achieve it, Could
 you give me an example?
 Suppose I have:







 *class Profile(models.Model):user = models.OneToOneField(
 settings.AUTH_USER_MODEL,on_delete = models.CASCADE,
 related_name="profile")location = models.ManyToManyField(Location)*


 Thank you

 Regards,
 Soumen

 On Wed, May 27, 2020 at 7:20 PM Chetan Ganji 
 wrote:

> select_related for fk and prefetch_related for m2m in django, you can
> chain them together
>
> Regards,
> Chetan Ganji
> +91-900-483-4183
> ganji.che...@gmail.com
> http://ryucoder.in
>
>
> On Wed, May 27, 2020 at 4:51 PM Soumen Khatua <
> soumenkhatua...@gmail.com> wrote:
>
>> Hi Folks,
>> I have many to many relationships and Foreign Key in the table, I'm
>> using select_realted(foreign key filed name) to optimize the query but I
>> want to fetch many to many and foreign key at the same time , How I can 
>> do
>> this in very optimized way?
>>
>> Thank You
>> Regards,
>> Soumen
>>
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>> 
>> .
>>
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Re: filter on multiple tables

2020-05-28 Thread אורי

Hi Soumen,

You can filter on another table by using __, for example:

User.objects.filter(profile__profiles__institute_name="Example")

Or:

User.objects.filter(profile__profiles__institute_name__in=["Example 1",
"Example 2"])
אורי
u...@speedy.net


On Thu, May 28, 2020 at 11:27 PM Soumen Khatua 
wrote:

> Actually I want to filter all users those are matched with currently
> logged in users based on location or education details like maybe
> institute_name or specialization. Is it possible to search in multiple
> tables?!
> I almost spent 2 days but still I stuck in the position.
> Any help would be appreciated.
>
> Thank You
>
> Regards,
> Soumen
>
>
>
>
> *class Location(models.Model):name = models.CharField(max_length = 15)*
>
>
>
>
>
>
>
> *class Profile(models.Model):user = models.OneToOneField(
> settings.AUTH_USER_MODEL,on_delete = models.CASCADE,
> related_name="profile")location =
> models.ManyToManyField(Location,related_name = 'user_locations')*
>
>
>
>
> *class Education(models.Model):profile = models.ForeignKey(Profile,
> on_delete=models.CASCADE,related_name="profiles")institute_name =
> models.CharField(max_length = 250)specialization =
> models.CharField(max_length = 100)*
>
> --
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> 
> .
>

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Re: how to use **kwargs if filters contains list of values

2020-05-28 Thread Manvi Tyagi


Yes Andreas Kuhne, I ultimately went with something like this only!!
Thanks for the reply.


On Thursday, May 28, 2020 at 5:37:33 PM UTC+5:30, Andréas Kühne wrote:
>
> Simply put - you can't. not without if statements.
>
> What I would do is something like this:
>
> query = Q()
>
> for item in kwargs.items():
>   if isinstance(item[1], list):
> query &= Q(**{f"{item[0]}__in": item[1]})
>   else:
> query &= Q(**{item[0]: item[1]})
>
> query_set = query_set.filter(query)
>
> Regards,
>
> Andréas
>
>
> Den tors 28 maj 2020 kl 12:45 skrev Manvi Tyagi  >:
>
>> i have a dict of filters , 
>> something like
>>
>> {
>> "name": "string",
>> "status": [
>>   "A", "B"
>> ],
>> "reg": "string",
>> "oc": [
>>   "As","jb"
>> ]
>>   }
>>
>>
>> ```query_set = query_set.filter(**filters)``` This works fine for all 
>> the filters whose type is not list , How do apply the filters on list 
>> values? 
>> PS: I know about __in know I can do something like 
>>   # if status_list:
>> # query_set = query_set.filter(status__in=status_list)
>>
>> BUT , 
>> 1. I dont want to use if else statemnets
>> 2. I want to have dynamic variables in the filters arguments and not 
>> hardcore ones like status__in
>>
>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "Django users" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to django...@googlegroups.com .
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/django-users/47e6ae26-82c9-433c-8de3-08b303004864%40googlegroups.com
>>  
>> 
>> .
>>
>

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Templates vs. source code

2020-05-28 Thread אורי

Django users,

There was a discussion in Stack Overflow related to an answer of mine - how
to access settings from templates in Django [
https://stackoverflow.com/a/53953578/1412564]. And I would like to know -
is it generally unsafe to expose all my settings to templates and why?
Should I use the updated answer and expose only specific settings to
templates? Because if a hacker can change my templates, they can also
change my .py files, and then they can give themselves any access they want
to. So what is better - expose all my settings to templates or only
specific settings which I consider safe?

Thanks,
Uri.
אורי
u...@speedy.net

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How models.Manager is working behind the scene and calling different serialize methods?

2020-05-28 Thread django-newbie

Hi, 
I am new to django and going through a tutorial and now confused with one 
particular implementation.

models.py

import json
from django.core.serializers import serialize

from django.db import models
from django.conf import settings

# Create your models here.


def upload_update_image(instance, filename):
return "updates/{owner}/{filename}".format(owner=instance.owner, 
filename=filename)

class UpdateQuerySet(models.QuerySet):
 
def serialize(self):
print("UpdateQuerySet serialize")
print(self.values("owner", "content", "image"))
list_values = list(self.values("owner", "content", "image"))
return json.dumps(list_values)


class UpdateManager(models.Manager):

def get_queryset(self):
print('get_queryset method')
return UpdateQuerySet(self.model, using=self._db)


class BasicUserUpdate(models.Model):
owner = models.ForeignKey(settings.AUTH_USER_MODEL,on_delete=models.CASCADE)
content = models.TextField(blank=True,null=True)
image = 
models.ImageField(blank=True,null=True,upload_to=upload_update_image,)
updated = models.DateTimeField(auto_now=True)
timestamp = models.DateTimeField(auto_now_add=True)

def __str__(self):
return self.content or ''

objects = UpdateManager()


def serialize(self):
print("BasicUserUpdate serialize")
try:
image = self.image.url
except:
image = ""
data = {
"content": self.content,
"owner": self.owner.id,
"image": image
}
data = json.dumps(data)
return data

  
views.py

from basic.models import BasicUserUpdate
from django.views import View
from django.http import HttpResponse


class BasicUserUpdateListView(View):
def get(self, request, *args, **kwargs):
qs = BasicUserUpdate.objects.all()
json_data = qs.serialize()
return HttpResponse(json_data, content_type='application/json')

class BasicUserUpdateDetailView(View):

def get(self, request,id, *args, **kwargs):
qs = BasicUserUpdate.objects.get(id=id)
json_data = qs.serialize()
return HttpResponse(json_data, content_type='application/json')

]


*At run time calling ListView, get below print messages*
get_queryset method
UpdateQuerySet serialize

*At run time calling DetailView, get below print messages*
get_queryset method
BasicUserUpdate serialize


*How Django is identifying which serialize method to be called? *

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filter on multiple tables

2020-05-28 Thread Soumen Khatua

Actually I want to filter all users those are matched with currently logged
in users based on location or education details like maybe institute_name
or specialization. Is it possible to search in multiple tables?!
I almost spent 2 days but still I stuck in the position.
Any help would be appreciated.

Thank You

Regards,
Soumen




*class Location(models.Model):name = models.CharField(max_length = 15)*







*class Profile(models.Model):user = models.OneToOneField(
settings.AUTH_USER_MODEL,on_delete = models.CASCADE,
related_name="profile")location =
models.ManyToManyField(Location,related_name = 'user_locations')*




*class Education(models.Model):profile = models.ForeignKey(Profile,
on_delete=models.CASCADE,related_name="profiles")institute_name =
models.CharField(max_length = 250)specialization =
models.CharField(max_length = 100)*

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Re: Migration dependency not added when field is altered

2020-05-28 Thread Erin Masatsugu

I understand that -- my question is why the AlterField operation in this 
case didn't add a migration dependency.

On Wednesday, May 27, 2020 at 6:44:16 PM UTC-10, Durai pandian wrote:
>
> When you make any changes to the field, AlterField will be added rather 
> than AddField.
>
> On Thu, May 28, 2020 at 7:32 AM Erin Masatsugu  > wrote:
>
>> If I have this a model in app A:
>> class AppAModel(models.Model):
>> name = models.CharField(max_length=50, default="")
>>
>> and this model in app B:
>> class AppBModel(models.Model):
>> name = models.CharField(max_length=50, default="")
>>
>> and a I add a foreign key to AppAModel in app C:
>> class AppCModel(models.Model):
>> my_field = models.ForeignKey(AppAModel, on_delete=models.CASCADE)
>>
>> the generated migration file correctly adds a dependency from app C to 
>> app A:
>> class Migration(migrations.Migration):
>>
>> dependencies = [
>> ('app_a', '_app_a_migration'),
>> ('app_c', '_app_c_migration'),
>> ]
>>
>> operations = [
>> migrations.CreateModel(
>> name='AppCModel',
>> fields=[
>> ('id', models.AutoField(auto_created=True, 
>> primary_key=True, serialize=False, verbose_name='ID')),
>> ('my_field', 
>> models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, 
>> to='ncm.AppAModel')),
>> ],
>> ),
>> ]
>>
>> However, if I then update my_field to instead have a foreign key to 
>> AppBModel, django doesn't add a migration dependency from app C to app B:
>> class Migration(migrations.Migration):
>>
>> dependencies = [
>> ('app_c', '_app_c_migration'),
>> ]
>>
>> operations = [
>> migrations.AlterField(
>> model_name='appcmodel',
>> name='my_field',
>> 
>> field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, 
>> to='metals.AppBModel'),
>> ),
>> ]
>>
>> I saw the response here 
>> https://groups.google.com/forum/#!searchin/django-users/migration$20dependency%7Csort:date/django-users/-h9LZxFomLU/ry_yeWGfDQAJ
>>  
>> so I don't believe this is expected behavior, but can someone confirm?
>>
>> Thank you!
>> Erin
>>
>> -- 
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>> "Django users" group.
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>> email to django...@googlegroups.com .
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>>  
>> 
>> .
>>
>
>
> -- 
> Thanks & Regards,
>
>
> *Durai pandianMobile  : +91-9611051220Email: ddp...@gmail.com 
>  *
>

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Re: how to use **kwargs if filters contains list of values

2020-05-28 Thread Andréas Kühne

Simply put - you can't. not without if statements.

What I would do is something like this:

query = Q()

for item in kwargs.items():
  if isinstance(item[1], list):
query &= Q(**{f"{item[0]}__in": item[1]})
  else:
query &= Q(**{item[0]: item[1]})

query_set = query_set.filter(query)

Regards,

Andréas


Den tors 28 maj 2020 kl 12:45 skrev Manvi Tyagi :

> i have a dict of filters ,
> something like
>
> {
> "name": "string",
> "status": [
>   "A", "B"
> ],
> "reg": "string",
> "oc": [
>   "As","jb"
> ]
>   }
>
>
> ```query_set = query_set.filter(**filters)``` This works fine for all the
> filters whose type is not list , How do apply the filters on list values?
> PS: I know about __in know I can do something like
>   # if status_list:
> # query_set = query_set.filter(status__in=status_list)
>
> BUT ,
> 1. I dont want to use if else statemnets
> 2. I want to have dynamic variables in the filters arguments and not
> hardcore ones like status__in
>
> --
> You received this message because you are subscribed to the Google Groups
> "Django users" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to django-users+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/django-users/47e6ae26-82c9-433c-8de3-08b303004864%40googlegroups.com
> 
> .
>

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how to use **kwargs if filters contains list of values

2020-05-28 Thread Manvi Tyagi

i have a dict of filters , 
something like

{
"name": "string",
"status": [
  "A", "B"
],
"reg": "string",
"oc": [
  "As","jb"
]
  }


```query_set = query_set.filter(**filters)``` This works fine for all the 
filters whose type is not list , How do apply the filters on list values? 
PS: I know about __in know I can do something like 
  # if status_list:
# query_set = query_set.filter(status__in=status_list)

BUT , 
1. I dont want to use if else statemnets
2. I want to have dynamic variables in the filters arguments and not 
hardcore ones like status__in

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Re: Can we use python related api's on the Django templates ?

2020-05-28 Thread Derek

While you cannot use Python operators and functions directly in the 
templates, you can write your own "wrappers" around those you need:

https://docs.djangoproject.com/en/3.0/howto/custom-template-tags/


On Wednesday, 27 May 2020 15:57:34 UTC+2, Daniel Roseman wrote:
>
> On Wednesday, 27 May 2020 13:21:24 UTC+1, ratnadeep ray wrote:
>>
>> Hi all, 
>>
>> Currently I am trying to print the type of a variable from the Django 
>> template html file as follows: 
>>
>> The type of feature list report for version 
>>> {%type(version)%} is
>>
>>
>> For the above, I am getting the following error: 
>>
>> Invalid block tag on line 9: 'type(version)'. Did you forget to register or 
>> load this tag?
>>
>>
>> So what's going wrong here? How can we use the python related api's (like 
>> type) from the html template files? I think inside the {%  %} we can 
>> use python related evaluations. Am I right? 
>>
>> Please throw some lights on this .
>>
>> Thanks. 
>>
>>
> No, you are wrong, and this is explicitly pointed out in the docs (
> https://docs.djangoproject.com/en/3.0/ref/templates/language/):
>
> > bear in mind that the Django template system is not simply Python 
> embedded into HTML. This is by design: the template system is meant to 
> express presentation, not program logic.
>
> --
> DR. 
>

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Re: Optimized Query

Re: filter on multiple tables

Re: how to use **kwargs if filters contains list of values

Templates vs. source code

How models.Manager is working behind the scene and calling different serialize methods?

filter on multiple tables

Re: Migration dependency not added when field is altered

Re: how to use **kwargs if filters contains list of values

how to use **kwargs if filters contains list of values

Re: Can we use python related api's on the Django templates ?

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