Cannot create type codec for composite type with certain field types.

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
postgresql, python
Domain
databases

Research direction

Start by reproducing the example through conn.set_type_codec with a composite type containing a jsonb field, then inspect the composite codec handling and PostgreSQL type-format constraints. Done means establishing support for the reported field types or clearly documenting the limitation and a supported workaround.

Written by the indexing model from the issue text.

Description

Hello, I noticed I can't create a type codec for a composite type if it has a field of type json, a jsonb or a geometry type. Why is so and is there a way to sidestep this issue?

import json
from dataclasses import dataclass

@dataclass
class Foo:
    data: dict

await conn.execute("CREATE TABLE foo (data jsonb NOT NULL);")

await conn.set_type_codec(
    "foo", 
    schema="public",
    encoder=lambda foo: (json.dumps(foo.data),), 
    decoder=lambda row: Foo(json.loads(row)), 
    format="tuple",
)

UnsupportedClientFeatureError: cannot decode type "public"."foo": text encoding of composite types is not supported
Dominant language
Python
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Avg merge
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Merged PRs (30d)
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