当改变列类型时，如何在两个相似的复合类型之间进行转换？

-- 定义两个相似的复合类型
CREATE TYPE type_a AS (
    id INT,
    name TEXT,
    value FLOAT
);

CREATE TYPE type_b AS (
    id INT,
    name TEXT,
    value NUMERIC
);

-- 创建一个函数来转换type_a到type_b
CREATE OR REPLACE FUNCTION convert_type_a_to_b(input type_a) RETURNS type_b AS $$
BEGIN
    RETURN (input.id, input.name, input.value::NUMERIC)::type_b;
END;
$$ LANGUAGE plpgsql;

import psycopg2

# 连接到数据库
conn = psycopg2.connect(database="yourdb", user="youruser", password="yourpassword", host="yourhost")

# 定义两个复合类型的类
class TypeA:
    def __init__(self, id, name, value):
        self.id = id
        self.name = name
        self.value = value

class TypeB:
    def __init__(self, id, name, value):
        self.id = id
        self.name = name
        self.value = value

# 示例数据
data_a = TypeA(1, "example", 123.45)

# 转换逻辑
data_b = TypeB(data_a.id, data_a.name, float(data_a.value))

# 打印转换后的结果
print(f"TypeB: id={data_b.id}, name={data_b.name}, value={data_b.value}")