當您產生activerecord對象時會發生什麼？

Question

有人可以幫我理解下面的代碼。

def self.with_optimistic_lock(attrs) 
    begin 
    payment = where(attrs).first_or_create 
    yield(payment) 
    payment.save! 
    rescue ActiveRecord::StaleObjectError, ActiveRecord::StatementInvalid, ActiveRecord::RecordInvalid => e 
    retry 
    end 
end 

其中attrs是散列參數。 Post是繼承自ActiveRecord::Base的類。

這是https://github.com/fantgeass/rails-test-tasks/blob/master/app/models/payment.rb

Answer 1

它產生的，就像任何其他塊將，使得提供給塊產生對象的代碼片段：

Post.with_optimistic_lock(:name => "Foo") do |post| 
    # The 'post' variable contains the ActiveRecord object yielded from the method 

    # Once this block ends, the method will resume at the `payment.save!` line 
end