PLEASE HELP! Django documentation, Writing Your First App, Part 4

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Atsunori Kaneshige

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Feb 3, 2019, 3:02:14 AM2/3/19

to Django users

Hi Django users,

I started using Django recently.

I am following the official Django tutorial.

I am just at Writing Your First Django App, Part4, and I have been just copying and pasting all codes.

But I have a problem in vote.

I inserted print(question) and this is printed in detail.html

also, question.id is also printed.

BUT, choice part doesn't seem working.

<THIS IS views.py>

def vote(request, question_id):

question = get_object_or_404(Question, pk=question_id)

print(question)

try:

selected_choice = question.choice_set.get(pk=request.POST['choice'])

except (KeyError, Choice.DoesNotExist) as e:

# Redisplay the question voting form.

print(e)

return render(request, 'polls/detail.html', {

'question': question,

'error_message': "You didn't select a choice.",

})

else:

selected_choice.votes += 1

selected_choice.save()

# Always return an HttpResponseRedirect after successfully dealing

# with POST data. This prevents data from being posted twice if a

# user hits the Back button.

return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

<THIS IS details.html>

<h1>{{ question.question_text }}</h1>

{% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}

{% csrf_token %}

{% for choice in question.choice_set.all %}

<label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br>

{% endfor %}

</form>

<br>

#printed

<br>

#printed

<br>

#<QuerySet []> #what is this? empty? why?

<br>

#printed

<br>

<h1>{{ question.question_text }}</h1>

#printed

<ul>

{% for choice in question.choice_set.all %}

<li>{{ choice.choice_text }}</li>

{% endfor %}

#nothing printed!

</ul>

Also when I click button 'vote', I only get error.

You didn't select a choice.

I am just copying and pasting so that I can understand Django, but I am having hard time in this Part 4.

I really appreciate advice from anybody!

Nori

Atsunori Kaneshige

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Feb 3, 2019, 3:08:55 AM2/3/19

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Oh, one note is that I am using postgresql.

everything else except vote function in views.py seems working.

Sorry, any help would be really appreciated!

Nori

Nitin Kalmaste

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Feb 3, 2019, 6:56:18 AM2/3/19

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Have you migrated database and added any question there?

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Carsten Fuchs

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Feb 3, 2019, 6:57:37 AM2/3/19

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Hi Nori,

does the choice actually exist?
Can you find it if you query the choices using the ORM in `./manage.py shell`?

Best regards,
Carsten

Am 03.02.19 um 03:59 schrieb Atsunori Kaneshige:

> Hi Django users,
>
> I started using Django recently.
> I am following the official Django tutorial.
> I am just at Writing Your First Django App, Part4, and I have been just copying and pasting all codes.
>
> But I have a problem in vote.
> I inserted print(question) and this is printed in detail.html
> also, question.id is also printed.
>
> BUT, choice part doesn't seem working.
>

> *<THIS IS views.py>*

> def vote(request, question_id):
> question = get_object_or_404(Question, pk=question_id)
> print(question)
> try:
> selected_choice = question.choice_set.get(pk=request.POST['choice'])
> except (KeyError, Choice.DoesNotExist) as e:
> # Redisplay the question voting form.
> print(e)
> return render(request, 'polls/detail.html', {
> 'question': question,
> 'error_message': "You didn't select a choice.",
> })
> else:
> selected_choice.votes += 1
> selected_choice.save()
> # Always return an HttpResponseRedirect after successfully dealing
> # with POST data. This prevents data from being posted twice if a
> # user hits the Back button.
> return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))
>

> *<THIS IS details.html>*

> <h1>{{ question.question_text }}</h1>
>
> {% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}
>
> <form action="{% url 'polls:vote' question.id %}" method="post">
> {% csrf_token %}
> {% for choice in question.choice_set.all %}
> <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}">
> <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br>
> {% endfor %}
> <input type="submit" value="Vote">
> </form>
>
> <br>
> {{ question }}
> #printed
> <br>
> {{ question.id }}
> #printed
> <br>

> _{{ question.choice_set.all }}_
> _#<QuerySet []> #what is this? empty? why?_

> <br>
> {{ question.question_text }}
> #printed
> <br>
> <h1>{{ question.question_text }}</h1>
> #printed
> <ul>

> _{% for choice in question.choice_set.all %}_
> _ <li>{{ choice.choice_text }}</li>_
> _{% endfor %}_
> _#nothing printed!_

> </ul>
>
> Also when I click button 'vote', I only get error.

> *You didn't select a choice.*
> *
> *

Malick Cisse

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Feb 3, 2019, 2:08:53 PM2/3/19

to Django users

Hi, copy and paste wouldn't actually make you understand Django. Try to write the code yourself and you see how quickly your understanding grow.

On Saturday, February 2, 2019 at 10:02:14 PM UTC-5, Atsunori Kaneshige wrote:

Atsunori Kaneshige

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Feb 3, 2019, 3:22:56 PM2/3/19

to Django users

Hi Nitin,

Thank you for your comment.

I did

jango-admin startproject mysite

and cd mysite, then

python manage.py runserver

and server is working, so I did

opython manage.py startapp polls

polls app was successfully created, and stopped the server because I wanted to user postgresql instead of the default SQLite3(?).

I did below

pg_ctl -D /user/local/var/posgres start

postgres successfully started running, then stopped

By the way, I registered polls app in settings.py (I just copied and pasted part of codes from the file below)

INSTALLED_APPS = [

'polls.apps.PollsConfig',

Also, I followed the way to add postgres as database, I looked as Django docs

DATABASES = {

'default': {

'ENGINE': 'django.db.backends.postgresql',

'NAME': 'Koitaro',

'USER': '',

'PASSWORD': '',

'HOST': '',

'PORT': '',

}

I did migration too, like migrate, makemigration etc, just copied and pasted from Django Docs

This is my models.py

import datetime

from django.db import models

from django.utils import timezone

# Create your models here.

class Question(models.Model):

question_text = models.CharField(max_length=200)

pub_date = models.DateTimeField('date published')

def __str__(self):

return self.question_text

def was_published_recently(self):

return self.pub_date >= timezone.now() - datetime.timedelta(days=1)

class Choice(models.Model):

question = models.ForeignKey(Question, on_delete=models.CASCADE)

choice_text = models.CharField(max_length=200)

votes = models.IntegerField(default=0)

def __str__(self):

return self.choice_text

mygration was successfully generated

from django.db import migrations, models

import django.db.models.deletion

class Migration(migrations.Migration):

initial = True

dependencies = [

]

operations = [

migrations.CreateModel(

name='Choice',

fields=[

('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),

('choice_text', models.CharField(max_length=200)),

('votes', models.IntegerField(default=0)),

migrations.CreateModel(

name='Question',

fields=[

('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),

('question_text', models.CharField(max_length=200)),

('pub_date', models.DateTimeField(verbose_name='date published')),

migrations.AddField(

model_name='choice',

name='question',

field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='polls.Question'),

]

When I go to admin, I added 5 or 6 questions, and successfully added in database.

the database name I made is 'Koitaro'.

I registered in settings.py and I have this database named as Koitaro in my posgresql

question has data, but choice thing doesn't seem having any data...

I really appreciate your thoughts.

Nori

Atsunori Kaneshige

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Feb 3, 2019, 3:23:51 PM2/3/19

to Django users

Atsunori Kaneshige

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Feb 3, 2019, 3:55:48 PM2/3/19

to Django users

Hi Carsten,

Sorry, are you talking about Writing Your First App, Part2? The page below?

https://docs.djangoproject.com/en/2.1/intro/tutorial02/

Yeah, when I tried this, there was something wrong.

I did that again. I copied and pasted my terminal below.

seems like migration was successful when I did before.

I am not sure what 'python sqlmigrate polls 001' is doing.

MacBook-Pro-3:mysite Koitaro$ python manage.py migrate

/Applications/anaconda3/lib/python3.6/site-packages/psycopg2/__init__.py:144: UserWarning: The psycopg2 wheel package will be renamed from release 2.8; in order to keep installing from binary please use "pip install psycopg2-binary" instead. For details see: <http://initd.org/psycopg/docs/install.html#binary-install-from-pypi>.

""")

Operations to perform:

Apply all migrations: admin, auth, contenttypes, polls, sessions

Running migrations:

No migrations to apply.

MacBook-Pro-3:mysite Koitaro$ python manage.py makemigrations polls

""")

No changes detected in app 'polls'

MacBook-Pro-3:mysite Koitaro$ python manage.py sqlmigrate polls 0001

""")

BEGIN;

-- Create model Choice

CREATE TABLE "polls_choice" ("id" serial NOT NULL PRIMARY KEY, "choice_text" varchar(200) NOT NULL, "votes" integer NOT NULL);

-- Create model Question

CREATE TABLE "polls_question" ("id" serial NOT NULL PRIMARY KEY, "question_text" varchar(200) NOT NULL, "pub_date" timestamp with time zone NOT NULL);

-- Add field question to choice

ALTER TABLE "polls_choice" ADD COLUMN "question_id" integer NOT NULL;

CREATE INDEX "polls_choice_question_id_c5b4b260" ON "polls_choice" ("question_id");

ALTER TABLE "polls_choice" ADD CONSTRAINT "polls_choice_question_id_c5b4b260_fk_polls_question_id" FOREIGN KEY ("question_id") REFERENCES "polls_question" ("id") DEFERRABLE INITIALLY DEFERRED;

COMMIT;

MacBook-Pro-3:mysite Koitaro$

After this, when I typed 'python manage.py shell',

By the way, I am not doing this in virtual environment, is it fine?

Django docs doesn't say anything about it.

Here is the result of shell

MacBook-Pro-3:mysite Koitaro$ python manage.py shell

""")

Python 3.6.5 |Anaconda, Inc.| (default, Apr 26 2018, 08:42:37)

Type 'copyright', 'credits' or 'license' for more information

IPython 6.4.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: from polls.models import Choice, Question

In [2]: Question.objects.all()

Out[2]: <QuerySet [<Question: What's up?>, <Question: How's going?>, <Question: Oh, are you OK?>, <Question: Where is she?>]>

In [3]: from django.utils import timezone

In [4]: q = Question(question_text='What's up?,pub_data=timezone.now())

File "<ipython-input-4-85ce5789a277>", line 1

q = Question(question_text='What's up?,pub_data=timezone.now())

SyntaxError: invalid syntax

In [5]: q = Question(question_text="What's up?",pub_data=timezone.now())

---------------------------------------------------------------------------

TypeError Traceback (most recent call last)

<ipython-input-5-bae574063418> in <module>()

----> 1 q = Question(question_text="What's up?",pub_data=timezone.now())

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/base.py in __init__(self, *args, **kwargs)

483 pass

484 for kwarg in kwargs:

--> 485 raise TypeError("'%s' is an invalid keyword argument for this function" % kwarg)

486 super().__init__()

487 post_init.send(sender=cls, instance=self)

TypeError: 'pub_data' is an invalid keyword argument for this function

In [6]: q = Question(question_text="What's up?",pub_date=timezone.now())

In [7]: q.save()

In [8]: q.id

Out[8]: 5

In [9]: q.question_text

Out[9]: "What's up?"

In [10]: q.pub_date

Out[10]: datetime.datetime(2019, 2, 3, 15, 43, 10, 354354, tzinfo=<UTC>)

In [11]: q.question_text = "What's up?"

In [12]: q.save()

In [13]: Question.objects.all()

Out[13]: <QuerySet [<Question: What's up?>, <Question: How's going?>, <Question: Oh, are you OK?>, <Question: Where is she?>, <Question: What's up?>]>

In [14]: from polls.models import Choice, Question

In [15]: Question.objects.all()

Out[15]: <QuerySet [<Question: What's up?>, <Question: How's going?>, <Question: Oh, are you OK?>, <Question: Where is she?>, <Question: What's up?>]>

In [16]: Question.objects.filter(question_text_startswith='What')

---------------------------------------------------------------------------

FieldError Traceback (most recent call last)

<ipython-input-16-09474b7667e7> in <module>()

----> 1 Question.objects.filter(question_text_startswith='What')

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/manager.py in manager_method(self, *args, **kwargs)

80 def create_method(name, method):

81 def manager_method(self, *args, **kwargs):

---> 82 return getattr(self.get_queryset(), name)(*args, **kwargs)

83 manager_method.__name__ = method.__name__

84 manager_method.__doc__ = method.__doc__

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.py in filter(self, *args, **kwargs)

842 set.

843 """

--> 844 return self._filter_or_exclude(False, *args, **kwargs)

845

846 def exclude(self, *args, **kwargs):

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.py in _filter_or_exclude(self, negate, *args, **kwargs)

860 clone.query.add_q(~Q(*args, **kwargs))

861 else:

--> 862 clone.query.add_q(Q(*args, **kwargs))

863 return clone

864

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in add_q(self, q_object)

1261 # So, demotion is OK.

1262 existing_inner = {a for a in self.alias_map if self.alias_map[a].join_type == INNER}

-> 1263 clause, _ = self._add_q(q_object, self.used_aliases)

1264 if clause:

1265 self.where.add(clause, AND)

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in _add_q(self, q_object, used_aliases, branch_negated, current_negated, allow_joins, split_subq)

1285 child, can_reuse=used_aliases, branch_negated=branch_negated,

1286 current_negated=current_negated, allow_joins=allow_joins,

-> 1287 split_subq=split_subq,

1288 )

1289 joinpromoter.add_votes(needed_inner)

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in build_filter(self, filter_expr, branch_negated, current_negated, can_reuse, allow_joins, split_subq, reuse_with_filtered_relation)

1162 if not arg:

1163 raise FieldError("Cannot parse keyword query %r" % arg)

-> 1164 lookups, parts, reffed_expression = self.solve_lookup_type(arg)

1165

1166 if not getattr(reffed_expression, 'filterable', True):

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in solve_lookup_type(self, lookup)

1026 if expression:

1027 return expression_lookups, (), expression

-> 1028 _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())

1029 field_parts = lookup_splitted[0:len(lookup_splitted) - len(lookup_parts)]

1030 if len(lookup_parts) > 1 and not field_parts:

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in names_to_path(self, names, opts, allow_many, fail_on_missing)

1387 )

1388 raise FieldError("Cannot resolve keyword '%s' into field. "

-> 1389 "Choices are: %s" % (name, ", ".join(available)))

1390 break

1391 # Check if we need any joins for concrete inheritance cases (the

FieldError: Cannot resolve keyword 'question_text_startswith' into field. Choices are: choice, id, pub_date, question_text

In [17]: Question.objects.filter(question_text__startswith='What')

Out[17]: <QuerySet [<Question: What's up?>, <Question: What's up?>]>

In [18]: from django.utils import timezone

In [19]: current_year = timezone.now().year

In [20]: Question.objects.get(pub_date__year=current_year)

---------------------------------------------------------------------------

MultipleObjectsReturned Traceback (most recent call last)

<ipython-input-20-05adfe5e79c1> in <module>()

----> 1 Question.objects.get(pub_date__year=current_year)

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/manager.py in manager_method(self, *args, **kwargs)

80 def create_method(name, method):

81 def manager_method(self, *args, **kwargs):

---> 82 return getattr(self.get_queryset(), name)(*args, **kwargs)

83 manager_method.__name__ = method.__name__

84 manager_method.__doc__ = method.__doc__

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.py in get(self, *args, **kwargs)

401 raise self.model.MultipleObjectsReturned(

402 "get() returned more than one %s -- it returned %s!" %

--> 403 (self.model._meta.object_name, num)

404 )

405

MultipleObjectsReturned: get() returned more than one Question -- it returned 5!

In [21]: current_year = timezone.now().year

In [22]: Question.objects.get(pub_date__year=current_year)

---------------------------------------------------------------------------

MultipleObjectsReturned Traceback (most recent call last)

<ipython-input-22-05adfe5e79c1> in <module>()

----> 1 Question.objects.get(pub_date__year=current_year)

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/manager.py in manager_method(self, *args, **kwargs)

80 def create_method(name, method):

81 def manager_method(self, *args, **kwargs):

---> 82 return getattr(self.get_queryset(), name)(*args, **kwargs)

83 manager_method.__name__ = method.__name__

84 manager_method.__doc__ = method.__doc__

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.py in get(self, *args, **kwargs)

401 raise self.model.MultipleObjectsReturned(

402 "get() returned more than one %s -- it returned %s!" %

--> 403 (self.model._meta.object_name, num)

404 )

405

MultipleObjectsReturned: get() returned more than one Question -- it returned 5!

In [23]: Question.objects.get(id=2)

Out[23]: <Question: How's going?>

In [24]: Question.objects.get(pk=1)

Out[24]: <Question: What's up?>

In [25]: q = Question.objects.get(pk=1)

In [26]: q.was_published_recently()

Out[26]: True

In [27]: q = Question.objects.get(pk=1)

In [28]: q.choice_set.all()

Out[28]: <QuerySet []>

In [29]: q.choice_set.create(choice_text='Not much',votes=0)

Out[29]: <Choice: Not much>

In [30]: q.choice_set.create(choice_text='The sky',votes=0)

Out[30]: <Choice: The sky>

In [31]: c = q.choice_set.create(choice_text='Just hacking again',votes=0)

In [32]: c.question

Out[32]: <Question: What's up?>

In [33]: q.choice_set.all()

Out[33]: <QuerySet [<Choice: Just hacking again>, <Choice: The sky>, <Choice: Not much>]>

In [34]: q.choice_set.count()

Out[34]: 3

In [35]: Choice.objects.filter(question_pub_date__year=current_year)

---------------------------------------------------------------------------

FieldError Traceback (most recent call last)

<ipython-input-35-ae43afb24822> in <module>()

----> 1 Choice.objects.filter(question_pub_date__year=current_year)

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/manager.py in manager_method(self, *args, **kwargs)

80 def create_method(name, method):

81 def manager_method(self, *args, **kwargs):

---> 82 return getattr(self.get_queryset(), name)(*args, **kwargs)

83 manager_method.__name__ = method.__name__

84 manager_method.__doc__ = method.__doc__

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.py in filter(self, *args, **kwargs)

842 set.

843 """

--> 844 return self._filter_or_exclude(False, *args, **kwargs)

845

846 def exclude(self, *args, **kwargs):

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.py in _filter_or_exclude(self, negate, *args, **kwargs)

860 clone.query.add_q(~Q(*args, **kwargs))

861 else:

--> 862 clone.query.add_q(Q(*args, **kwargs))

863 return clone

864

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in add_q(self, q_object)

1261 # So, demotion is OK.

1262 existing_inner = {a for a in self.alias_map if self.alias_map[a].join_type == INNER}

-> 1263 clause, _ = self._add_q(q_object, self.used_aliases)

1264 if clause:

1265 self.where.add(clause, AND)

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in _add_q(self, q_object, used_aliases, branch_negated, current_negated, allow_joins, split_subq)

1285 child, can_reuse=used_aliases, branch_negated=branch_negated,

1286 current_negated=current_negated, allow_joins=allow_joins,

-> 1287 split_subq=split_subq,

1288 )

1289 joinpromoter.add_votes(needed_inner)

1162 if not arg:

1163 raise FieldError("Cannot parse keyword query %r" % arg)

-> 1164 lookups, parts, reffed_expression = self.solve_lookup_type(arg)

1165

1166 if not getattr(reffed_expression, 'filterable', True):

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in solve_lookup_type(self, lookup)

1026 if expression:

1027 return expression_lookups, (), expression

-> 1028 _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())

1029 field_parts = lookup_splitted[0:len(lookup_splitted) - len(lookup_parts)]

1030 if len(lookup_parts) > 1 and not field_parts:

/Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.py in names_to_path(self, names, opts, allow_many, fail_on_missing)

1387 )

1388 raise FieldError("Cannot resolve keyword '%s' into field. "

-> 1389 "Choices are: %s" % (name, ", ".join(available)))

1390 break

1391 # Check if we need any joins for concrete inheritance cases (the

FieldError: Cannot resolve keyword 'question_pub_date' into field. Choices are: choice_text, id, question, question_id, votes

In [36]: c = q.choice_set.filter(choice_text__startswith='Just hackin'))

File "<ipython-input-36-93150b748243>", line 1

c = q.choice_set.filter(choice_text__startswith='Just hackin'))

SyntaxError: invalid syntax

In [37]: c = q.choice_set.filter(choice_text__startswith='Just hackin')

In [38]: c.delete()

Out[38]: (1, {'polls.Choice': 1})

In [39]:

Seems like choice exites and shell thing is working correctly???

Thank you for your comment.

looking forward to hearing from you.

Nori

Atsunori Kaneshige

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Feb 3, 2019, 3:58:49 PM2/3/19

to Django users

Here is the codes about choice

In [27]: q = Question.objects.get(pk=1)

In [28]: q.choice_set.all()

Out[28]: <QuerySet []>

In [29]: q.choice_set.create(choice_text='Not much',votes=0)

Out[29]: <Choice: Not much>

In [30]: q.choice_set.create(choice_text='The sky',votes=0)

Out[30]: <Choice: The sky>

In [31]: c = q.choice_set.create(choice_text='Just hacking again',votes=0)

In [32]: c.question

Out[32]: <Question: What's up?>

In [33]: q.choice_set.all()

Out[33]: <QuerySet [<Choice: Just hacking again>, <Choice: The sky>, <Choice: Not much>]>

In [34]: q.choice_set.count()

Out[34]: 3

choice exits, or correctly working?

Nori

---> 82 return getattr(self.get_queryset(), name)(*args,<span c

Nitin Kalmaste

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Feb 3, 2019, 4:08:34 PM2/3/19

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You have to add Choices for each questions you have created in database like the process is same as you used for the questions.

To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/b1699379-b28e-4900-a06c-4267efbb4446%40googlegroups.com.

Carsten Fuchs

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Feb 3, 2019, 8:20:39 PM2/3/19

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Well, you're adding choices to q = Question.objects.get(pk=1).
But is this also the question you call the view with?

I suggest you add a few more print statements below your existing

print(question)

For example:

print(question.pk)
print(question.choice_set.all())

# Or, a bit more verbose, for example:
for c in question.choice_set.all():
print(c.pk, c)

# Is the following a valid PK among the choices printed above?
print(request.POST['choice'])

Best regards,
Carsten

Am 2019-02-03 um 16:58 schrieb Atsunori Kaneshige:
> *_Here is the codes about choice_*

>
>
> In [27]: q = Question.objects.get(pk=1)
>
>
> In [28]: q.choice_set.all()
>
> Out[28]: <QuerySet []>
>
>
> In [29]: q.choice_set.create(choice_text='Not much',votes=0)
>
> Out[29]: <Choice: Not much>
>
>
> In [30]: q.choice_set.create(choice_text='The sky',votes=0)
>
> Out[30]: <Choice: The sky>
>
>
> In [31]: c = q.choice_set.create(choice_text='Just hacking again',votes=0)
>
>
> In [32]: c.question
>
> Out[32]: <Question: What's up?>
>
>
> In [33]: q.choice_set.all()
>
> Out[33]: <QuerySet [<Choice: Just hacking again>, <Choice: The sky>, <Choice: Not much>]>
>
>
> In [34]: q.choice_set.count()
>
> Out[34]: 3
>
>
>
> choice exits, or correctly working?
>
> Nori
>
> On Sunday, February 3, 2019 at 10:55:48 AM UTC-5, Atsunori Kaneshige wrote:
>
> Hi Carsten,
>
> Sorry, are you talking about Writing Your First App, Part2? The page below?

> https://docs.djangoproject.com/en/2.1/intro/tutorial02/ <https://docs.djangoproject.com/en/2.1/intro/tutorial02/>

>
> Yeah, when I tried this, there was something wrong.
>

> *_I did that again. I copied and pasted my terminal below._*
> *_seems like migration was successful when I did before._*
> *_I am not sure what 'python sqlmigrate polls 001' is doing._*

>
>
> MacBook-Pro-3:mysite Koitaro$ python manage.py migrate
>

> /Applications/anaconda3/lib/python3.6/site-packages/psycopg2/__init__.py:144: UserWarning: The psycopg2 wheel package will be renamed from release 2.8; in order to keep installing from binary please use "pip install psycopg2-binary" instead. For details see: <http://initd.org/psycopg/docs/install.html#binary-install-from-pypi <http://initd.org/psycopg/docs/install.html#binary-install-from-pypi>>.

>
> """)
>
> Operations to perform:
>
> Apply all migrations: admin, auth, contenttypes, polls, sessions
>
> Running migrations:
>
> No migrations to apply.
>
> MacBook-Pro-3:mysite Koitaro$ python manage.py makemigrations polls
>

>
> """)
>
> No changes detected in app 'polls'
>
> MacBook-Pro-3:mysite Koitaro$ python manage.py sqlmigrate polls 0001
>

>
> """)
>
> BEGIN;
>
> --
>
> -- Create model Choice
>
> --
>
> CREATE TABLE "polls_choice" ("id" serial NOT NULL PRIMARY KEY, "choice_text" varchar(200) NOT NULL, "votes" integer NOT NULL);
>
> --
>
> -- Create model Question
>
> --
>
> CREATE TABLE "polls_question" ("id" serial NOT NULL PRIMARY KEY, "question_text" varchar(200) NOT NULL, "pub_date" timestamp with time zone NOT NULL);
>
> --
>
> -- Add field question to choice
>
> --
>
> ALTER TABLE "polls_choice" ADD COLUMN "question_id" integer NOT NULL;
>
> CREATE INDEX "polls_choice_question_id_c5b4b260" ON "polls_choice" ("question_id");
>
> ALTER TABLE "polls_choice" ADD CONSTRAINT "polls_choice_question_id_c5b4b260_fk_polls_question_id" FOREIGN KEY ("question_id") REFERENCES "polls_question" ("id") DEFERRABLE INITIALLY DEFERRED;
>
> COMMIT;
>
> MacBook-Pro-3:mysite Koitaro$
>
>
>
>

> *_After this, when I typed 'python manage.py shell',_*
> *_By the way, I am not doing this in virtual environment, is it fine?_*
> *_Django docs doesn't say anything about it._*
>
> *_Here is the result of shell_*

>
> MacBook-Pro-3:mysite Koitaro$ python manage.py shell
>

>
> """)
>
> Python 3.6.5 |Anaconda, Inc.| (default, Apr 26 2018, 08:42:37)
>
> Type 'copyright', 'credits' or 'license' for more information
>
> IPython 6.4.0 -- An enhanced Interactive Python. Type '?' for help.
>
>

> In [1]: frompolls.modelsimportChoice, Question

>
>
> In [2]: Question.objects.all()
>
> Out[2]: <QuerySet [<Question: What's up?>, <Question: How's going?>, <Question: Oh, are you OK?>, <Question: Where is she?>]>
>
>
> In [3]: fromdjango.utilsimporttimezone
>
>
> In [4]: q = Question(question_text='What's up?,pub_data=timezone.now())
>
> File "<ipython-input-4-85ce5789a277>", line 1
>
> q = Question(question_text='What's up?,pub_data=timezone.now())
>
> ^
>
> SyntaxError:invalid syntax
>
>
>
> In [5]: q = Question(question_text="What's up?",pub_data=timezone.now())
>
> ---------------------------------------------------------------------------
>
> TypeError Traceback (most recent call last)
>
> <ipython-input-5-bae574063418>in <module>()
>

> ----> 1q =Question(question_text="What's up?",pub_data=timezone.now())
>
>
> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/base.pyin __init__(self, *args, **kwargs)

>
> 483 pass
>
> 484 forkwarg inkwargs:
>

> --> 485 raiseTypeError("'%s' is an invalid keyword argument for this function"%kwarg)

>
> 486 super().__init__()
>
> 487 post_init.send(sender=cls,instance=self)
>
>
> TypeError: 'pub_data' is an invalid keyword argument for this function
>
>
> In [6]: q = Question(question_text="What's up?",pub_date=timezone.now())
>
>
> In [7]: q.save()
>
>

> In [8]: q.id <http://q.id>

>
> Out[8]: 5
>
>
> In [9]: q.question_text
>
> Out[9]: "What's up?"
>
>
> In [10]: q.pub_date
>
> Out[10]: datetime.datetime(2019, 2, 3, 15, 43, 10, 354354, tzinfo=<UTC>)
>
>
> In [11]: q.question_text = "What's up?"
>
>
> In [12]: q.save()
>
>
> In [13]: Question.objects.all()
>
> Out[13]: <QuerySet [<Question: What's up?>, <Question: How's going?>, <Question: Oh, are you OK?>, <Question: Where is she?>, <Question: What's up?>]>
>
>

> In [14]: frompolls.modelsimportChoice, Question

>
>
> In [15]: Question.objects.all()
>
> Out[15]: <QuerySet [<Question: What's up?>, <Question: How's going?>, <Question: Oh, are you OK?>, <Question: Where is she?>, <Question: What's up?>]>
>
>
> In [16]: Question.objects.filter(question_text_startswith='What')
>
> ---------------------------------------------------------------------------
>
> FieldError Traceback (most recent call last)
>
> <ipython-input-16-09474b7667e7>in <module>()
>
> ----> 1Question.objects.filter(question_text_startswith='What')
>
>
> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/manager.pyin manager_method(self, *args, **kwargs)
>
>    80 defcreate_method(name,method):
>
>    81 defmanager_method(self,*args,**kwargs):
>
> ---> 82 returngetattr(self.get_queryset(),name)(*args,**kwargs)
>
>    83 manager_method.__name__ =method.__name__
>
>    84 manager_method.__doc__ =method.__doc__
>
>

> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.pyin filter(self, *args, **kwargs)

>
> 842 set.
>
> 843 """
>
> --> 844 returnself._filter_or_exclude(False,*args,**kwargs)
>
> 845
>
> 846 defexclude(self,*args,**kwargs):
>
>

> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/query.pyin _filter_or_exclude(self, negate, *args, **kwargs)

>
> 860 clone.query.add_q(~Q(*args,**kwargs))
>
> 861 else:
>
> --> 862 clone.query.add_q(Q(*args,**kwargs))
>
> 863 returnclone
>
> 864
>
>

> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.pyin add_q(self, q_object)

>
>    1261 # So, demotion is OK.
>
>    1262 existing_inner ={a fora inself.alias_map ifself.alias_map[a].join_type ==INNER}
>
> -> 1263 clause,_ =self._add_q(q_object,self.used_aliases)
>
>    1264 ifclause:
>
>    1265 self.where.add(clause,AND)
>
>

> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.pyin _add_q(self, q_object, used_aliases, branch_negated, current_negated, allow_joins, split_subq)

>
>    1285 child,can_reuse=used_aliases,branch_negated=branch_negated,
>
>    1286 current_negated=current_negated,allow_joins=allow_joins,
>
> -> 1287 split_subq=split_subq,
>
>    1288 )
>
>    1289 joinpromoter.add_votes(needed_inner)
>
>

> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.pyin build_filter(self, filter_expr, branch_negated, current_negated, can_reuse, allow_joins, split_subq, reuse_with_filtered_relation)
>
> 1162 ifnotarg:
>
> 1163 raiseFieldError("Cannot parse keyword query %r"%arg)

>
> -> 1164 lookups,parts,reffed_expression =self.solve_lookup_type(arg)
>
>    1165
>
>    1166 ifnotgetattr(reffed_expression,'filterable',True):
>
>
> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.pyin solve_lookup_type(self, lookup)
>
>    1026 ifexpression:
>
>    1027 returnexpression_lookups,(),expression
>
> -> 1028 _,field,_,lookup_parts =self.names_to_path(lookup_splitted,self.get_meta())
>
>    1029 field_parts =lookup_splitted[0:len(lookup_splitted)-len(lookup_parts)]
>
>    1030 iflen(lookup_parts)>1andnotfield_parts:
>
>

> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/sql/query.pyin names_to_path(self, names, opts, allow_many, fail_on_missing)

>
>    1387 )
>
>    1388 raise FieldError("Cannot resolve keyword '%s' into field. "
>
> -> 1389 "Choices are: %s" % (name, ", ".join(available)))
>
>    1390 break
>
>    1391 # Check if we need any joins for concrete inheritance cases (the
>
>
> FieldError: Cannot resolve keyword 'question_text_startswith' into field. Choices are: choice, id, pub_date, question_text
>
>
> In [17]: Question.objects.filter(question_text__startswith='What')
>
> Out[17]: <QuerySet [<Question: What's up?>, <Question: What's up?>]>
>
>
> In [18]: fromdjango.utilsimporttimezone
>
>
> In [19]: current_year = timezone.now().year
>
>
> In [20]: Question.objects.get(pub_date__year=current_year)
>
> ---------------------------------------------------------------------------
>
> MultipleObjectsReturned Traceback (most recent call last)
>
> <ipython-input-20-05adfe5e79c1>in <module>()
>
> ----> 1Question.objects.get(pub_date__year=current_year)
>
>
> /Applications/anaconda3/lib/python3.6/site-packages/django/db/models/manager.pyin manager_method(self, *args, **kwargs)
>
>    80 defcreate_method(name,method):
>
>    81 defmanager_method(self,*args,**kwargs):
>
> ---> 82 returngetattr(self.get_queryset(),name)(*args,<span c
>

> --

Atsunori Kaneshige

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Feb 4, 2019, 1:45:34 AM2/4/19

to Django users

Hi Nitin,

Thank you!

I finally understood what you said.

Now working fine. Actually it was working, but I did not understand.

Thank you!

Nori

Atsunori Kaneshige

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Feb 4, 2019, 1:52:44 AM2/4/19

to Django users

Hi Carsten,

Thank you!

I finally understood what's happening.

I should have added choices into each question.

Now, choice_set.all thing is working!

Thank you for your advice!

Nori

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