Nested custom types in Postgres break `asyncpg.Record` subclassing

• asyncpg version: v0.25.0

• PostgreSQL version: 14

• Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
  the issue with a local PostgreSQL install?: on-premise

• Python version: 3.10.1

• Platform: linux

• Do you use pgbouncer?: no

• Did you install asyncpg with pip?: yes

• If you built asyncpg locally, which version of Cython did you use?: n/a

• Can the issue be reproduced under both asyncio and
  uvloop?: n/a

It would appear that nested types are not converted to a user specified record_class, and instead will always use asyncpg.Record.

For example:

CREATE TYPE my_custom_type AS (
    id int,
    filename text,
    sql text
);

CREATE TABLE my_table (
    files my_custom_type[] NOT NULL,
);

SELECT * FROM my_table

If you specify a custom record_class, then the record from SELECT * FROM my_table will be your subclass. However, the value inside record['files'] will use the asyncpg.Record class, rather than the custom one specified.

What should actually happen?

I think if a user specifies a record_class, then this class should always be used, even for nested custom types. It's quite unexpected behaviour for asyncpg to use the default class when a custom one has been specified.

首先，使用报告中描述的自定义 PostgreSQL 类型、数组列、SELECT 查询和自定义 record_class 重现该问题。跟踪嵌套自定义类型值的解码方式以及 record_class 的传递方式；当 record['files'] 中的记录使用指定的子类而不是 asyncpg.Record，并且此案例有回归测试覆盖时，即表示完成。