如何为Django模型生成HASH [英] How to generate HASH for Django model

问题描述

我正在尝试为我的10位Django模型生成唯一的HASH值，我尝试了这些方法，但出现此错误

I am trying to generate unique HASH values for my Django models of 10 digit i have tried these methods but i am getting this error

return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: column hash_3 is not unique

这是我尝试过的内容：

import os
import time
import hashlib
from os import path
from binascii import hexlify
from django.db import models
from django.contrib import admin
from django.core.files.storage import FileSystemStorage
#------------------------------------------------------------------------------ 

def _createHash():
    """This function generate 10 character long hash"""
    hash = hashlib.sha1()
    hash.update(str(time.time()))
    return  hash.hexdigest()[:-10]


class tags(models.Model):
    """ This is the tag model """

    seo_url1 = models.URLField()
    seo_url2 = models.URLField()
    seo_url3 = models.URLField()
    tagDescription = models.TextField()                 # Tag Description
    tag = models.CharField(max_length=200)              # Tag name
    tagSlug = models.CharField(max_length=400)          # Extra info can be added to the existing tag using this field
    updatedAt = models.DateTimeField(auto_now=True)     # Time at which tag is updated
    createdAt = models.DateTimeField(auto_now_add=True) # Time at which tag is created
    hash_1 = models.CharField(max_length=10,default=_createHash(),unique=True)
    hash_2 = models.CharField(max_length=10,default=_createHash(),unique=True)
    hash_3 = models.CharField(max_length=10,default=_createHash(),unique=True)

我也尝试过这种方法：

def _createHash():
    """This function generate 10 character long hash"""
    return hexlify(os.urandom(5))

我有一个脚本，每次运行时都会将数据插入此模型我上面提到的错误脚本..是否还有其他方法可以执行..我想将唯一的哈希值存储到列 hash_1，hash_2，hash_3 中。

I have a script which inserts data into this model every time i run my script i got above mentioned error ..is there any other way of doing this..i want to store unique hash values into columns hash_1,hash_2,hash_3.

推荐答案

不要在您的字段中调用 _createHash（）函数，而只是将引用传递给模型中的可调用对象，例如

Don't call the _createHash() function in your field, but just pass the reference to the callable in your model, e.g.

hash_1 = models.CharField(max_length=10,default=_createHash,unique=True)

正如Lennart Regebro在他的回答中提到的，每次您将获得相同的值您尝试启动服务器。

As Lennart Regebro mentioned in his answer, you'll get the same value for each time you start the server in your attempt.

Django文档这样说：

Field.default

Field.default

该字段的默认值。这可以是值，也可以是
可调用对象。如果可以调用，则每次创建新的
对象时都会调用它。

The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.

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