Postgresql – SQL how to prevent duplicates in STRING_AGG when joining multiple tables

Here’s the relational model for the database that I’m going to talk about (a show can have multiple actors and multiple genres): Relational model
(sorry, don’t have enough reputation to insert an image)

What I would like to achieve is to get every detail about a specific show + the genres that it has + the actors that played in the show and their IDs.

I tried:

SELECT shows.*,
       STRING_AGG(g.name, ', ')                AS genres,
       STRING_AGG(CAST(a.id AS VARCHAR), ', ') AS actor_ids,
       STRING_AGG(a.name, ', ')                AS actors
FROM shows
         LEFT JOIN show_genres sg ON shows.id = sg.show_id
         LEFT JOIN genres g ON g.id = sg.genre_id
         LEFT JOIN show_characters sc ON shows.id = sc.show_id
         LEFT JOIN actors a ON sc.actor_id = a.id
WHERE shows.id = 1390
GROUP BY shows.id

The result:

Note: only showing the problematic columns

The problem: After joining the "show_characters" and the "actors" table, there are a lot of duplicate data in the string aggregations.

Question: How would I solve this? Without having duplicate data.

My workaround:

@connection_handler
def get_show_by_id(cursor: 'RealDictCursor', id: int) -> 'RealDictRow':
    """

    Args:
        cursor: a cursor which returns dictionaries (use @connection.connection_handler decorator)
        id: number of items shows on a single page

    Returns:
        All show details in a RealDictRow + genres(as a concatenated string) + actors in a list
        containing the actors ids and names in a RealDictRow

    """
    query = """
    SELECT shows.*,STRING_AGG(g.name,',') AS genres
    FROM shows
    LEFT JOIN show_genres sg ON shows.id = sg.show_id
    LEFT JOIN genres g ON sg.genre_id = g.id
    WHERE shows.id = %s
    GROUP BY shows.id
    """
    val = (id,)
    cursor.execute(query, val)
    shows = cursor.fetchone()

    query = """
    SELECT a.id,a.name
    FROM actors a
    RIGHT JOIN show_characters sc ON a.id = sc.actor_id
    RIGHT JOIN shows s ON sc.show_id = s.id
    WHERE s.id = %s
    GROUP BY a.id
    """
    val = (id,)
    cursor.execute(query, val)
    actors = cursor.fetchall()
    shows["actors"] = actors
    return shows

Note for workaround: Used two separate queries to achieve the result I wanted, but I’d like to know how would I be able to do this with one SQL query.

Side note: I’d be really happy to receive any feedback about my code in general, or suggestion about how people usually handle when they get back multiple data from an SQL query, do they just split it? Or is it better to write a separate query, like I did, so I get the data in a separate list right away? What about my docstring? I just started trying to use them, not sure if the way I’m doing it is good or not.