CODEWITHSUNDEEP
pythondjangomodels
Павел Иванов
Павел Иванов

Reputation: 1913

TypeError: coercing to Unicode: need string or buffer, NoneType found

I'm wading throught the Django tutorial, part 2: https://docs.djangoproject.com/en/1.9/intro/tutorial02/ and in a place where we attach several choices to one question

# Display any choices from the related object set -- none so far.
>>> q.choice_set.all()
[]

I got an error:

/home/paulmad/env/local/lib/python2.7/site-packages/IPython/lib/pretty.pyc in _repr_pprint(obj, p, cycle)
    692     """A pprint that just redirects to the normal repr function."""
    693     # Find newlines and replace them with p.break_()
--> 694     output = repr(obj)
    695     for idx,output_line in enumerate(output.splitlines()):
    696         if idx:

/home/paulmad/env/local/lib/python2.7/site-packages/django/db/models/query.pyc in __repr__(self)
    235         if len(data) > REPR_OUTPUT_SIZE:
    236             data[-1] = "...(remaining elements truncated)..."
--> 237         return repr(data)
    238 
    239     def __len__(self):

/home/paulmad/env/local/lib/python2.7/site-packages/django/db/models/base.pyc in __repr__(self)
    457     def __repr__(self):
    458         try:
--> 459             u = six.text_type(self)
    460         except (UnicodeEncodeError, UnicodeDecodeError):
    461             u = '[Bad Unicode data]'

TypeError: coercing to Unicode: need string or buffer, NoneType found

Here are my models:

from __future__ import unicode_literals

import datetime
from django.db import models
from django.utils import timezone
from django.utils.encoding import python_2_unicode_compatible
# Create your models here.

@python_2_unicode_compatible
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 __unicode__(self):
        return unicode(self.quesion_text) or u''

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

@python_2_unicode_compatible
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):
        self.choice_text

    def __unicode__(self):
        return unicode(self.choice_text) or u''

Django 1.9.1, how to resolve this problem?

Upvotes: 0

Views: 2685

Answers (3)

ruddra
ruddra

Reputation: 51938

In your model, update method called __str__(self).

class Choice(models.Model):
    choice_text = models.CharField(max_length=255, null=True)

    def __str__(self):
       return self.choice_text if self.choice_next else ''

Upvotes: 1

Alasdair
Alasdair

Reputation: 308769

You are using @python_2_unicode_compatible, so you should there is no need to define __unicode__ and __str__.

You only need to define __unicode__ if you are using Python 2 without the @python_2_unicode_compatible decorator.

You should change your models to something like:

@python_2_unicode_compatible
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)

@python_2_unicode_compatible
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):
        self.choice_text

You shouldn't need code like unicode(self.choice_text) or u'' in your methods - the CharField should default to the empty string when a value isn't set.

Upvotes: 0

Павел Иванов
Павел Иванов

Reputation: 1913

In fact, it was needed only to add return to str before self.choice_text.

Upvotes: 0

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