Python peewee加入了多个表

Question

I want to be able to join multiple tables in peewee. However the scenario is a little difficult for me to figure out how to get it to work with peewee.

I have the following tables:

Ticket TicketCategory TicketBooking Event

Here are my models:

class TicketCategory(BaseModel):
    venue_id = IntegerField()
    name = CharField()
    description = CharField()

class Ticket(BaseModel):
    event = ForeignKeyField(Event)
    category = ForeignKeyField(TicketCategory)
    order_number = IntegerField()
    tier_name = CharField()
    num_available = IntegerField()
    price = DecimalField()

class TicketBooking(BaseModel):
    user_id = IntegerField()
    ticket = ForeignKeyField(Ticket, related_name="ticketbookings")
    price_paid = DecimalField()
    created = DateTimeField()
    deleted = DateTimeField()

class Event(BaseModel):
    venue_id = IntegerField()
    date = DateField()
    event_image_url = CharField()
    start = TimeField()
    end = TimeField()

Now I want to run a query which will select all the ticketbookings for a given user. After running my join, I want all the info to be loaded -- I don't want another query to be launched when I access ticketbooking.ticket.category.name or ticketbooking.ticket.event.description

I cannot just do this:

return TicketBooking.select(TicketBooking, Ticket, TicketCategory, Event).join(Ticket).join(TicketCategory).join(Event).where(
        TicketBooking.user_id == user_id,
        TicketBooking.deleted >> None
)

Because Event is not a foreign key on TicketCategory, so I get an error. Any help would be much appreciated.

Answer 1

Going to try answering this one more time.

(TicketBooking
 .select(
     TicketBooking, 
     Ticket, 
     TicketCategory, 
     Event)
 .join(Ticket)
 .join(TicketCategory)
 .join(Event)
 .where(
     TicketBooking.user_id == user_id,
     TicketBooking.deleted >> None
 ))

You're almost there. Try instead:

(TicketBooking
 .select(
     TicketBooking, 
     Ticket, 
     TicketCategory, 
     Event)
 .join(Ticket)
 .join(TicketCategory)
 .switch(Ticket)  # <-- switch the "query context" back to ticket.
 .join(Event)
 .where(
     TicketBooking.user_id == user_id,
     TicketBooking.deleted >> None
 ))

Answer 2

尝试.join(Event, on=(TicketCategory.venue_id == Event.venue_id))