在python中生成唯一字符串最简单的方法之一是使用uuid模块。如果你想得到字母数字输出，你也可以简单地使用base64编码：

import uuid
import base64
uuid = base64.b64encode(uuid.uuid4().bytes).replace('=', '')

# sample value: 1Ctu77qhTaSSh5soJBJifg

然后，您可以将此代码放在模型的save方法中，或使用它定义自定义模型字段。

下面是在不将该字段设为主键的情况下执行此操作的方法：

from django.db import IntegrityError

class MyTemporaryObject(models.Model):
    auto_pseudoid = models.CharField(max_length=16, blank=True, editable=False, unique=True)
    # add index=True if you plan to look objects up by it
    # blank=True is so you can validate objects before saving - the save method will ensure that it gets a value

    # other fields as desired

    def save(self, *args,**kwargs):
        if not self.auto_pseudoid:
            self.auto_pseudoid = generate_random_alphanumeric(16)
            # using your function as above or anything else
        success = False
        failures = 0
        while not success:
            try:
                super(MyTemporaryObject, self).save(*args,**kwargs)
            except IntegrityError:
                 failures += 1
                 if failures > 5: # or some other arbitrary cutoff point at which things are clearly wrong
                     raise
                 else:
                     # looks like a collision, try another random value
                     self.auto_pseudoid = generate_random_alphanumeric(16)
            else:
                 success = True

与使用字段作为主键相比，这样可以避免两个问题：
1)Django的内置关系字段需要整数键
2)Django使用数据库中主键的存在作为save应该更新现有记录而不是插入新记录的标志，这意味着如果主键字段发生冲突，它会悄悄地覆盖该行中的其他内容。

试试看：
下面的if语句是为了确保模型是可更新的。
如果没有if语句，每次重新保存模型时都将更新id字段，因此每次都将创建一个新模型

from uuid import uuid4
from django.db import IntegrityError

class Book(models.Model):
    id = models.CharField(primary_key=True, max_length=32)

    def save(self, *args,**kwargs):
        if self.id:
            super(Book, self).save(*args,**kwargs)
            return

        unique = False
        while not unique:
            try:
                self.id = uuid4().hex
                super(Book, self).save(*args,**kwargs)
            except IntegrityError:
                self.id = uuid4().hex
            else:
                unique = True

下面的代码片段使用Python自带的secrets库，处理id冲突，并在没有id冲突时继续传递完整性错误。
ID 0TCKybG1qgAhRuEN、yJariA4QN42E9aLf、AZOMrzlkJ-RKh4dp的示例

import secrets
from django.db import models, IntegrityError

class Test(models.Model):
    pk = models.CharField(primary_key=True, max_length=32)

    def save(self, *args,**kwargs):
        unique = False
        while not unique:
            try:
                self.pk = secrets.token_urlsafe(12)
                super(Test, self).save(*args,**kwargs)
            except IntegrityError as e :
                # keep raising the exception if it's not id collision error
                if not 'pk' in e.args[0]:
                    unique = True
                    raise e  
            else:
                unique = True