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pythondjangodjango-modelsdjango-migrations

Can't do migrations - ... has no field named 'questions'

I'm trying to figure out why does Django return's this error when trying to migrate after makemigrations. I tried to change related names and delete last migrations but nothing works.

Maybe you see what's the problem?

Error after migrate: django.core.exceptions.FieldDoesNotExist: LanguageQuizSitting has no field named 'questions'

Models.py

from django.db import models
from SolutionsForLanguagesApp import models as sfl_models
from jsonfield import JSONField
import random

class LanguageQuiz(models.Model):
    name = models.CharField(max_length=40)
    language = models.OneToOneField(sfl_models.Language)


class Question(models.Model):
    language_quiz = models.ForeignKey(LanguageQuiz,related_name='questions')
    text = models.TextField()

class Answer(models.Model):
    question = models.ForeignKey(Question,related_name='answers')
    text = models.TextField()
    correct = models.BooleanField()

class LanguageQuizSitting(models.Model):
    user = models.OneToOneField(sfl_models.User)
    quiz = models.OneToOneField(LanguageQuiz)
    date_opened = models.DateTimeField(auto_created=True)
    date_closed = models.DateTimeField(null=True)
    max_questions = models.IntegerField()

    def load_questions(self):
        questions = random.sample(self.quiz.questions,self.max_questions)
        for question in questions:
            SittingQuestion.objects.create(question=question,sitting=self)

    def get_next_question(self):
        q = self.questions.filter(answered=0)
        if len(q)>0:
            return q[0]
        else:
            return False

class SittingQuestion(models.Model):
    sitting = models.ForeignKey(LanguageQuizSitting,related_name='questions',on_delete=models.CASCADE)
    question = models.ForeignKey(Question, related_name='SittingQuestions')
    answered = models.BooleanField(default=0)
    result = models.BooleanField(default=0)

LAST MIGRATION

class Migration(migrations.Migration):

    dependencies = [
        ('language_tests', '0001_initial'),
    ]

    operations = [
        migrations.AlterField(
            model_name='question',
            name='language_quiz',
            field=models.ForeignKey(related_name='questions', to='language_tests.LanguageQuiz'),
        ),
        migrations.AlterField(
            model_name='sittingquestion',
            name='question',
            field=models.ForeignKey(related_name='sitting_questions', to='language_tests.Question'),
        ),
        migrations.AlterField(
            model_name='sittingquestion',
            name='sitting',
            field=models.ForeignKey(related_name='questions', to='language_tests.LanguageQuizSitting'),
        ),
    ]

TRACEBACK:

(venv) C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2>python manage.py migrate
Operations to perform:
  Synchronize unmigrated apps: essay, smart_selects, true_false, super_inlines, staticfiles, multichoice, messages, nested_inline, quiz, django_extensions, django_tables2, constance, crispy_forms
  Apply all migrations: language_tests, database, admin, sessions, auth, contenttypes, SolutionsForLanguagesApp
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
  Installing custom SQL...
Running migrations:
  Rendering model states... DONE
  Applying language_tests.0002_auto_20160711_1524...Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\core\management\__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\core\management\__init__.py", line 346, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\core\management\base.py", line 394, in run_from_argv
    self.execute(*args, **cmd_options)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\core\management\base.py", line 445, in execute
    output = self.handle(*args, **options)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\core\management\commands\migrate.py", line 222, in handle
    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\migrations\executor.py", line 110, in migrate
    self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\migrations\executor.py", line 148, in apply_migration
    state = migration.apply(state, schema_editor)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\migrations\migration.py", line 115, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\migrations\operations\fields.py", line 201, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\backends\base\schema.py", line 484, in alter_field
    old_db_params, new_db_params, strict)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\backends\sqlite3\schema.py", line 203, in _alter_field
    self._remake_table(model, alter_fields=[(old_field, new_field)])
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\backends\sqlite3\schema.py", line 140, in _remake_table
    self.create_model(temp_model)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\backends\base\schema.py", line 236, in create_model
    definition, extra_params = self.column_sql(model, field)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\backends\base\schema.py", line 135, in column_sql
    db_params = field.db_parameters(connection=self.connection)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\fields\related.py", line 2010, in db_parameters
    return {"type": self.db_type(connection), "check": []}
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\fields\related.py", line 2001, in db_type
    rel_field = self.related_field
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\fields\related.py", line 1904, in related_field
    return self.foreign_related_fields[0]
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\fields\related.py", line 1638, in foreign_related_fields
    return tuple(rhs_field for lhs_field, rhs_field in self.related_fields if rhs_field)
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\fields\related.py", line 1625, in related_fields
    self._related_fields = self.resolve_related_fields()
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\fields\related.py", line 1618, in resolve_related_fields
    else self.rel.to._meta.get_field(to_field_name))
  File "C:\Users\Milano\PycharmProjects\FutileStudio\SolutionsForLanguages_2\venv\lib\site-packages\django\db\models\options.py", line 554, in get_field
    raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name))
django.core.exceptions.FieldDoesNotExist: LanguageQuizSitting has no field named 'questions'
Solution

  • So the matter is the following one:

    questions = random.sample(self.quiz.questions,self.max_questions)

    self.quiz go there :

    quiz = models.OneToOneField(LanguageQuiz)

    and quiz.questions go there :

    class LanguageQuiz(models.Model):
    name = models.CharField(max_length=40)
    language = models.OneToOneField(sfl_models.Language)

    the matter is questions doesn't exist in LanguageQuiz.