如何在中保存记录在rails中有许多关联

# app/models/user.rb
class User < ApplicationRecord
  has_many :posts
end

# app/models/post.rb
class Post < ApplicationRecord
  belongs_to :user
end

$ rails generate migration CreateUsers
$ rails generate migration CreatePosts

# db/migrate/[timestamp]_create_users.rb
class CreateUsers < ActiveRecord::Migration[6.0]
  def change
    create_table :users do |t|
      t.string :name
      t.timestamps
    end
  end
end

# db/migrate/[timestamp]_create_posts.rb
class CreatePosts < ActiveRecord::Migration[6.0]
  def change
    create_table :posts do |t|
      t.string :title
      t.text :content
      t.references :user, foreign_key: true
      t.timestamps
    end
  end
end

user = User.create(name: "John Doe")
post = user.posts.build(title: "Hello World", content: "This is my first post")
post.save

user = User.find(1)
posts = user.posts

user = User.find(1)
post = user.posts.find(1)
post.title = "New Title"
post.save