Question

我有一个表格“开关和快照”。一台Switch有很多快照，一个Snapshot属于一个Switch。我无法通过关联创建新的快照。在我的代码下面。

df1['zipcode'] = np.where(df1['address1'].isin(df2['address1']), df2['zipcode'], 'no_match')



ValueError                                Traceback (most recent call last)
<ipython-input-176-499624d43d5c> in <module>
----> 1 df1['zipcode'] = np.where(df1['address1'].isin(df2['address1']), df2['zipcode'], 'no_match')
      2 df1

ValueError: operands could not be broadcast together with shapes (5,) (6,) ()

应用/模型

2.6.3 :014 > switch = Switch.new
 => #<Switch id: nil, switch: nil, ip_address: nil, created_at: nil, updated_at: nil> 
2.6.3 :015 > switch.create_snapshot
NoMethodError (undefined method `create_snapshot' for #<Switch:0x00000000039950e0>)

通过迁移配置的psql

class Switch < ApplicationRecord

  has_many :snapshots

end

class Snapshot < ApplicationRecord

  belongs_to :switch

end

Answer 1

首先创建开关，之后便可以创建类似这样的快照

switch = Switch.new 
switch.save
or
switch = Switch.create(switch_params)

然后

switch.snapshots.create(snapshot_params)

如果要在创建交换机时创建快照，则应使用嵌套属性https://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html

Answer 2

您需要在父模型上添加accepts_nested_attributes_for :model。

嵌套属性允许您通过父级将属性保存在关联记录上。默认情况下，嵌套属性更新处于关闭状态，您可以使用#accepts_nested_attributes_for类方法启用它。启用嵌套属性时，将在模型上定义属性编写器。（来自api.rubyonrails.org）

Answer 3

要一起创建关联的对象，可以有这样的另一种方法

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    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:798)
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    java.lang.Thread.run(Thread.java:748)

创建switch = Switch.new(swich_params) switch.snapshots.build switch.save后，还将创建关联的switch。

我如何通过activerecord关联创建新对象

3 个答案: