Question

我检查了很多类似的问题，但没有人在django shell中遇到过这样的问题：

我在Ubuntu 16.04 LTS上使用Django 2和DRF 3.7.7与Python 3.6和PostgreSQL 10.1。我正在编写预订应用程序并尝试使用OneToOneField扩展Django用户模型（使用指南here而不使用Signals＆＃39;方法）。我已经有一些使用Python 2.7编写的经验，但这是我第一次使用Django。

所以这是我的models.py：

from django.db import models
from django.contrib.auth.models import User

# Create your models here.

SPORTS_CHOICES = (
    ('Mountain', 'Mountain climbing'),
    ('Offroad', 'Offroad Driving'),
    ('Rafting', 'Rafting'),
    ('Cycling', 'Cycling'),
    ('Ski', 'Skiing'),
)


class ListField(models.TextField):

    "ListField stores List of element"

    SPLIT_CHAR= ';'

    def __init__(self, *args, list_choices=None, **kwargs):
        super(ListField, self).__init__(*args, **kwargs)
        if list_choices is None:
            list_choices = []
        self.list_choices = list_choices

    def get_prep_value(self, value):
        if value is None or value == "":
            return None
        res = self.SPLIT_CHAR.join(value)
        return res

    def value_to_string(self, obj):
        value = self._get_val_from_obj(obj)
        return self.get_prep_value(value)


class Profile(models.Model):

    "The Profile of a user with details are stored in this model."

    user = models.OneToOneField(User, on_delete=models.CASCADE, max_length=11)
    first_name = models.TextField(max_length=50,null=True)
    last_name = models.TextField(max_length=100,null=True)

    # The default username is phone number (Ver. 1.0)

    phone_number = models.TextField(max_length=11,default=user)
    avatar = models.ImageField(default='../Static/1.jpeg')
    GENDER_CHOICES = (
        ('M','Male'),
        ('F','Female'),
    )
    gender = models.CharField(max_length=1,choices=GENDER_CHOICES)
    city = models.TextField(max_length=25)
    description = models.TextField(max_length=2000, null=True)
    interests = ListField(choices=SPORTS_CHOICES)
    date_of_birth = models.DateField(auto_now_add=True)
    USER_TYPES = (
        ('User','Normal User'),
        ('Leader','Tour Leader'),
        ('Admin','Administrator'),
    )
    user_type = models.TextField(choices=USER_TYPES)
    join_date = models.DateTimeField(auto_now_add=True)
    official_docs = models.ImageField(default='../Static/1.jpeg')
    group_name = models.TextField(null=True)
    debit_card_number = models.IntegerField(null=True)
    favorite_music = ListField( null=True)

正如您在上面的代码中看到的，它基本上是由几种不同的数据类型扩展的Django User模型。（关于主题，但我尝试使用电话号码作为用户名，但是它不接受user.username作为phone_number字段中的默认值，为什么？）现在问题是，每当我想保存我的模型时shell，仅使用必填字段，并使用＆＃34; null = true＆＃34;：

保留字段

>>> user = User.objects.create_user(username='01234567890')
>>> test = Profile.objects.create(user=user,gender='M',city='NY',interests='[Ski]',user_type='User')

我收到以下错误：

Traceback (most recent call last):
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
psycopg2.IntegrityError: null value in column "first_name" violates not-null constraint
DETAIL:  Failing row contains (9, null, null, Booking.Profile.user, ../Static/1.jpeg, M, NY, null, [;S;k;i;], 2018-02-24, User, 2018-02-24 05:18:54.256013+00, ../Static/1.jpeg, null, null, null, 15).


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/query.py", line 417, in create
    obj.save(force_insert=True, using=self.db)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 729, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 759, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 842, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 880, in _do_insert
    using=using, raw=raw)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/query.py", line 1125, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1280, in execute_sql
    cursor.execute(sql, params)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: null value in column "first_name" violates not-null constraint
DETAIL:  Failing row contains (9, null, null, Booking.Profile.user, ../Static/1.jpeg, M, NY, null, [;S;k;i;], 2018-02-24, User, 2018-02-24 05:18:54.256013+00, ../Static/1.jpeg, null, null, null, 15).
>>> user = User.objects.create_user(username='01234567890')
>>> test = Profile.objects.create(user=user,gender='M',city='NY',interests='[Ski]',user_type='User')
Traceback (most recent call last):
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
psycopg2.IntegrityError: null value in column "first_name" violates not-null constraint
DETAIL:  Failing row contains (9, null, null, Booking.Profile.user, ../Static/1.jpeg, M, NY, null, [;S;k;i;], 2018-02-24, User, 2018-02-24 05:18:54.256013+00, ../Static/1.jpeg, null, null, null, 15).


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/query.py", line 417, in create
    obj.save(force_insert=True, using=self.db)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 729, in save
    force_update=force_update, update_fields=update_fields)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 759, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 842, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/base.py", line 880, in _do_insert
    using=using, raw=raw)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/query.py", line 1125, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1280, in execute_sql
    cursor.execute(sql, params)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/amir/.virtualenvs/Django/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
django.db.utils.IntegrityError: null value in column "first_name" violates not-null constraint
DETAIL:  Failing row contains (9, null, null, Booking.Profile.user, ../Static/1.jpeg, M, NY, null, [;S;k;i;], 2018-02-24, User, 2018-02-24 05:18:54.256013+00, ../Static/1.jpeg, null, null, null, 15).

但是当我给它们值时，我能够分配模型，保存模型甚至序列化数据（我还没有复制序列化器类，因为它只是一个继承自ModelSerializer的简单序列化器而且没有问题，所以它有点偏离主题）：

>>> test = Profile.objects.create(user=user,first_name='Amir',last_name='Amir',gender='M',city='NY',description='',interests='[Ski]',group_name='',debit_card_number='1',favorite_music='1',user_type='User')
>>> test.save()
>>> print(repr(test))
<Profile: Profile object (11)>
>>> serial = ProfileSerializer(test)
>>> print(repr(serial.data))
{'user': 15, 'first_name': 'Amir', 'last_name': 'Amir', 'phone_number': 'Manjaro.Profile.user', 'avatar': '../Static/1.jpeg', 'gender': 'M', 'city': 'NY', 'description': '', 'interests': '[Ski]', 'date_of_birth': '2018-02-24', 'user_type': 'User', 'join_date': '2018-02-24T05:44:00.188963Z', 'official_docs': '../Static/1.jpeg', 'group_name': '', 'debit_card_number': 1, 'favorite_music': '1'}

我知道还有其他几个问题，但这个问题让我很担心。我可以有一个解决方法并保存一些默认值，但我需要将其中一些留空。另外，有趣的是，ImageField没有任何空白问题！对于名为＆＃34; group_name＆＃34;的字段也是如此我只是传递一个空字符串，看起来python / django就可以了！是否有一组要设置的属性？我必须分配默认值吗？我使用OneToOneField做错了什么或采取了错误的方法吗？请帮忙！

Answer 1

所以根据你的问题，如果你想在模型字段中有空值，那么你在表格中使用时，指定null=True, blank=True空白也很重要。您是否已生成（并应用）所有迁移？字段，用于存储您想要的几乎所有类型的数据）。

此外，Django docs州：

避免在基于字符串的字段（如CharField和）上使用null TextField，除非你有一个很好的理由。如果是基于字符串的字段 has null = True，这意味着它有两个可能的“无数据”值： NULL和空字符串。在大多数情况下，拥有两个是多余的 “无数据”的可能值; Django约定是使用空的字符串，而不是NULL。

然后根据您的代码，您创建了class ListField(models.TextField)来存储元素列表。请查看PostgreSQL specific model fields | Django docs。您已经在Django中实现了ArrayField，您可以使用它。（还JSONfield，它可以存储你想要的几乎所有类型的数据。）

Django ReST框架 - 不接受的扩展用户模型＆＃34; null = true＆＃34;

1 个答案: