Returning arrays of composite types from Postgres

[domma]

I have a sql query that uses array_agg to return multiple values in a single column. The statement is something like

select id, array_agg(other_id) as other_ids from some_table group by id

The query is stored in a file and executed via sqlx::query_file_as!(MyStruct, "path/to/query.sql"). The target struct looks like this:

pub struct MyStruct { id: i32, emails: Option<Vec<i32>> }

This works fine as long as the vector only contains a single basic type. But I want to return more complex types and use array_agg(row(other_id, another_value, ...)). In that case I get the following error:

unsupported type RECORD[] of column #2

I also gave Postgres composite types a try and create a my_type type in postgres and use it with array_agg(row(...)::my_type). In that case the error changes into:

unsupported type _my_type of column #2

I implemented a struct for my_type as described at https://docs.rs/sqlx/0.5.9/sqlx/postgres/types/index.html#composite-types but cannot see any difference. The error just stays the same.

The docs look like a Vec<T> of a composite type should be supported, but I cannot get it to work. Would somebody be willing to provide a working example?