如何使用预定义的字母缩写部分声明自动递增的字母数字id字段(Django python) [英] How to declare a auto-incrementing alphanumerical id field with predefined aplphabetic part (Django python)

问题描述

我正在用Django开发应用程序.

I am developing an app in Django.

我想在模型中插入一个自动递增的字母数字ID字段，默认情况下，该字段具有一个固定的字母部分和一个自动递增的数字部分. 但是我也希望将可用性从管理部分更改为另一个id字母数字和ID，其中字母数字和数字部分不同. 请注意:我不想覆盖django默认ID字段，我只想在模型中包含一个字段，该字段将自动递增的字母数字值作为默认值.

I want to insert in my model an auto-incrementing alphanumerical ID field, having, by default, a fixed alphabetical part and an auto-incrementing numerical part. But I also want the availability to change, from admin section, this id to another alphanumerical one, with a different alphanumerical and numerical part. Please note: I don't want to overwrite the django default id field, I just want to include in my model a field that gets as default value an auto-incrementing alphanumerical value.

示例:

所需的字母常量部分:ITM

Desired alphabetical constant part: ITM

所需的数字自动递增部分:00000

Desired numerical auto-incrementing part: 00000

这样，当模型中的每个对象生成时，都将获得默认的渐进值，例如:ITM00001，ITM00002，ITM00003，...

So that every object of my model, when generated, get default progressive values like: ITM00001, ITM00002, ITM00003, ...

我想将我的管理部分中的字段值更改为例如:ABC0000001，DFG0051，RST034，...

I would like to change the field value from my admin section into, for example: ABC0000001, DFG0051, RST034, ...

最大字段长度:10(也可以更高)

Max field length: 10 (It can be also higher)

我意识到我必须使用AutoField并以某种方式将常量字符串与自动递增的数字变量连接在一起，但是我不知道该怎么做.

I realize that I have to use AutoField and to somehow join the constant string with the auto-incrementing numerical variable, but I don't know how to do it.

class my_model(models.Model):

    Field_1 = models.CharField(max_length=10, blank=True, null=True)
    static_ID = models.AutoField(???)

推荐答案

已解决:

由于我不需要特定的ID长度，也不需要两个连续ID之间的恒定增量，因此每次创建模型中的对象时，都可以使用time.time()获取唯一的时间编号.然后，我可以将那个时间数字转换为字符串，并用一个常量前缀将其连接起来.

Since I don't need a specific length for my id, nor a constant increment between two consecutive ids, I can use time.time() to get a unique time number every time the object in the model is created. Then I can turn that time number into a string and concatenate it with a constant prefix.

在 models.py 中:

import time

def return_timestamped_id():
    prefix = "ITCH"     
    timestamp = str(int(time.time()*10000000))
    default_value = prefix + timestamp
    return(default_value)


class my_model(models.Model):        
    Field_1 = models.CharField(max_length=256)
    static_ID = models.CharField(max_length=256, blank=False, null=False, default=return_timestamped_id)

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