ruby - Sequel如何保存新建的关联模型？

Question

假设我有这样的东西:

# Schema:
DB.create_table :transactions do
    primary_key :id
    foreign_key :card_id, :cards
    Integer     :amount
end
DB.create_table :cards do
    primary_key :id
    foreign_key :transaction_id, :transactions
    Intger      :number
end

# Models:
class Transaction < Sequel::Model
    one_to_one :card
end
class Card < Sequel::Model
    one_to_one :transaction
end

我如何使它工作，以便它保存 trans、card 以及它们各自的关联？

trans = Transaction.new(:amount => 100)
card = Card.new(:number => 4000500060007000)
trans.card = card
trans.save

就目前而言，这是行不通的，因为 card 没有首先保存，Sequel 会抛出“无主键”错误。如果我先保存card，它不会得到transaction的id。

基本上，我正在努力避免这种情况:

# Save without associations first, but this will assign primary keys
trans.save
card.save

# Now, manually create associations
trans.card = card
card.trans = trans

# Re-save again, this time with associations
trans.save
card.save

Answer 1

您可能想尝试将关联类型更改为更类似的内容:

# Schema:
DB.create_table :transactions do
    primary_key :id
    Integer     :amount
end
DB.create_table :cards do
    primary_key :id
    foreign_key :transaction_id, :transactions
    Integer      :number
end

# Models:
class Transaction < Sequel::Model
    one_to_many :card
end
class Card < Sequel::Model
    one_to_one :transaction
end

现在你创建为:

trans = Transaction.new(:amount => 100)
trans.save
trans.add_card(:number => 4000500060007000)

这将允许所有相同的选项，并允许(但当然不要求)将交易拆分到多张卡上。