Question

我有一个链接表关联的两个模型没有id字段，而是一个复合键[product_id，product_set_id]。

我对它们进行了唯一性验证。

我正在尝试设置一个嵌套表单，但是我注意到了以下问题：更新时，似乎activerecord正在尝试创建一个新条目，因此它失败了。

例如，这是一个发送到补丁的示例参数哈希：

Parameters: {"product_set"=>{"name"=>"Marea", "created_by_id"=>"1", "product_product_sets_attributes"=>{"0"=>{"product_id"=>"420", "product_set_id"=>"4", "_destroy"=>"1"}, "1"=>{"product_id"=>"423", "product_set_id"=>"4", "_destroy"=>"0"}}}, "commit"=>"Atualizar", "id"=>"4"}

我已经读过某个地方，当没有：参数中的id时AR假设它必须创建一个新记录......但是我怎么能告诉它不要尝试创建一个新记录？

validates :product_set_id, uniqueness: { scope: :product_id, message: "This product is already part of this set." }

编辑：

型号：

class ProductProductSet < ActiveRecord::Base
  belongs_to :product
  belongs_to :product_set
  validates :product_set_id, uniqueness: { scope: :product_id, message: "This product is already part of this set." }
end

class ProductSet < ActiveRecord::Base
  belongs_to :created_by, class_name: 'User',  foreign_key: 'created_by_id'
  has_many :product_product_sets, dependent: :destroy
  has_and_belongs_to_many :products, :join_table => :product_product_sets
  # has_many :products, through: :product_product_sets, source: :product

  accepts_nested_attributes_for :product_product_sets, :allow_destroy => true
end

product_sets_controller.rb

def product_set_params
  params.require(:product_set).permit(:name, :created_by_id, product_product_sets_attributes: [:product_id, :product_set_id, '_destroy'])
end

查看（当然没有完成）：

= simple_form_for(@product_set) do |f|
    - if @product_set.errors.any?
        .alert.alert-danger
            %ul
                - @product_set.errors.full_messages.each do |msg|
                    %li= msg
    .form-inputs
        .form-group
            = f.input :name, class: 'form-control'
            = f.association :created_by, class: 'form-control'
            / = text_field_tag 'product_set[product_ids][]', nil, { multiple: true, class: "form-control" }
            / = link_to 'add', 'javascript:void(0);', id: "add_link"
        .existing-products
            = f.fields_for( :product_product_sets, include_id: false ) do |builder| 
                = image_tag builder.object.product.image.url(:thumb)
                = builder.hidden_field :product_id
                = builder.hidden_field :product_set_id
                = builder.check_box :_destroy
                = builder.label :_destroy, "Remove Product"

Answer 1

在你的update action / params hash中，我认为你需要将集合对象id作为数组传递。这样的事可能呢？

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner input = new Scanner(System.in);
    String str = input.nextLine();

    doubleStr(str);
}
public static void doubleStr(String s)
{
    char[] array = s.toCharArray();
    for(char a: array)
    {
        if(a>='0' && a<='9')
        {
            System.out.print(a);
        }else if(a=='!')
        {
            for(int i=0; i<=2; i++)
            {
                System.out.print(a);
            }
        }
        else
        {
            for(int i=0; i<=1; i++)
            {
                System.out.print(a);
            }
        }

    }
}

我的理解是有限的，但我认为由于Rails默认情况下不支持复合键，你肯定需要"product_product_sets_attributes"=> { "id" => [product.id, product_set.id] }，然后在模型中需要以下语法风格???

composite keys gem

如果不是这样的话，有兴趣了解更多。

用于与多个密钥和唯一性关联的嵌套表单在更新时失败

1 个答案: