在 Python SQL Alchemy 中创建基于字符串的序列 [英] Create a String based sequence in Python SQL Alchemy

问题描述

我正在尝试在 SQLAlchemy ORM 中创建一个基于字符串的序列.我知道最佳实践是使用基于整数的列来管理表的 ID，但在我的情况下，由于项目的某些要求，我需要将数据存储为基于字符串的 ID PK.

I'm trying to create a String based sequence in SQLAlchemy ORM. I know that the best practice is to use a Integer based column to manage ID of a table but in my case, due to some requirements of the project I need to store the data as a String based PK for ID's.

我知道在某些数据库中可以使用基于字符串的序列来存储数据，例如:

I know that in some databases it is possible to store data using a string based sequence like:

• AAA1"
• AAA2"
• AAAN"

但在 SQL 炼金术中我无法通过使用 序列 方法.它只生成基于整数的序列，我找不到在序列生成中附加"前缀的选项.

But in SQL alchemy I can't achieve this by using Sequence method. It only generates Integer based sequences and I can't find an options to "append" a prefix in the sequence generation.

有一个简单的解决方案来实现这一目标吗?

There is a easy solution to achieve this?

推荐答案

你可以在 PostgreSQL 中这样做，类似于:

You can do this in PostgreSQL similar to this:

CREATE TABLE test(
   id text PRIMARY KEY,
   val text
);

CREATE SEQUENCE test_id_seq OWNED BY test.id;

ALTER TABLE test
   ALTER id SET DEFAULT to_hex(nextval('test_id_seq'));

在那个例子中，我使用了 to_hex 函数来获取十六进制表示，但你可以使用任何你喜欢的表达式.

In that example I used the to_hex function to get the hexadecimal representation, but you can use any expression you like.

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