FieldDoesNotExist Error in Tutorial Part 1

[Derek Ng]

Hi,

I'm am trying to follow along with the tutorial, but keep getting this error when I migrate the models. Here is my models.py file for the polls app:

from django.db import models

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

class Choice(models.Model):
    question = models.ForeignKey(Question)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

Then, when I use the makemigrations and migrate commands, I get this error:

Operations to perform:
  Apply all migrations: auth, admin, sessions, contenttypes, polls
Running migrations:
  Applying polls.0001_initial...Traceback (most recent call last):
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/options.py", line 414, in get_field_by_name
    return self._name_map[name]
AttributeError: 'Options' object has no attribute '_name_map'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/options.py", line 417, in get_field_by_name
    return cache[name]
KeyError: <class 'polls.models.Question'>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/core/management/commands/migrate.py", line 160, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/migrations/executor.py", line 63, in migrate
    self.apply_migration(migration, fake=fake)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/migrations/executor.py", line 97, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/migrations/migration.py", line 107, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/migrations/operations/fields.py", line 37, in database_forwards
    field,
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/backends/sqlite3/schema.py", line 167, in add_field
    self._remake_table(model, create_fields=[field])
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/backends/sqlite3/schema.py", line 128, in _remake_table
    self.create_model(temp_model)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/backends/schema.py", line 209, in create_model
    definition, extra_params = self.column_sql(model, field)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/backends/schema.py", line 112, in column_sql
    db_params = field.db_parameters(connection=self.connection)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/fields/related.py", line 1784, in db_parameters
    return {"type": self.db_type(connection), "check": []}
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/fields/related.py", line 1775, in db_type
    rel_field = self.related_field
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/fields/related.py", line 1681, in related_field
    return self.foreign_related_fields[0]
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/fields/related.py", line 1439, in foreign_related_fields
    return tuple(rhs_field for lhs_field, rhs_field in self.related_fields)
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/fields/related.py", line 1426, in related_fields
    self._related_fields = self.resolve_related_fields()
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/fields/related.py", line 1419, in resolve_related_fields
    else self.rel.to._meta.get_field_by_name(to_field_name)[0])
  File "/Users/derekng/Documents/projects/django-tutorial/lib/python3.4/site-packages/django/db/models/options.py", line 420, in get_field_by_name
    % (self.object_name, name))
django.db.models.fields.FieldDoesNotExist: Question has no field named <class 'polls.models.Question'>

I can't figure out what I am doing wrong. I tried googling, but to no avail.

Thanks in advanced,

Derek

[Adailton Nascimento]

Use:

import datetime

class Question(models.Model):
    question_text = models.CharField(max_length=200)

    pub_date = models.DateTimeField(auto_now=True)
 
    class Meta:
       ordering = ['-pub_date']


    def __str__(self):
       return self.question_text

delete all objects of your paste migrates. and run: PS:[for this option must delete the db]= python manage.py syncdb or use: makemigrations and then migrate .

Att;

Adailton do nascimento