Nextcord Dynamically Get Choices

I am trying to use nextcord to get all the choices from a user's inventory, but I am having trouble getting the user_id for my fetch_choices function. See below for some more details.

My slash command looks like this, (... is where I want userid):

async def duel(interaction: nextcord.Interaction, item: str = nextcord.SlashOption("item", choices=fetch_choices(...)), quantity: int = 1, side: str = "h"):

This is my fetch_choices code:

def fetch_choices(user_id):
    c.execute("SELECT * FROM items WHERE user_id=?", (user_id,))
    rows = c.fetchall()
    items = {}
    for row in rows:
        item = row[1],
        items.update({item[0]: item[0]})
    return items

My question is how can I get the user id, and pass it to fetch_choices?

from Nextcord Dynamically Get Choices