使用按钮/链接将固定值传递给字段 [英] Passing a fixed value to a field using a button/link

问题描述

如何使用 Rails 中的按钮或链接将对象的字段设置为固定值?看起来这应该是一个相当基本的程序，但我没有成功.一个例子是将产品模型的 parent_id 设置为 nil(相关的早期问题 通过 Rails 中的 link_to 更新字段).我设法通过将文本字段留空的表单来实现此目的:

How can I set a field of an object to a fixed value using a button or link in Rails? It seems like this should be a fairly basic procedure, but I haven't been successful with it. An example would be to set the parent_id of a product model to nil (related earlier question Update field through link_to in Rails). I have managed to achieve this through a form by leaving the text field empty:

<%= form_for @product do |f| %>    
    <%= f.label :parent_id %>
    <%= f.text_field :parent_id %>
    <%= f.submit "Update", class: "btn" %>  
<% end %>

但是如何在没有文本字段的情况下完成此操作，只需使用一个按钮，以便在按下按钮时将 parent_id 设置为 nil?我也尝试在隐藏字段中设置 parent_id，但这不起作用.

But how can this be done without a text field, simply using a button, so that the parent_id is set to nil when the button is pressed? I have also tried to set the parent_id in a hidden field, but that doesn't work.

<%= form_for @product do |f| %>
   <%= f.hidden_field parent_id: nil %>
   <%= f.submit "Remove", class: "btn" %>
<% end %>

用于编辑/更新操作的控制器如下所示.

The controller looks like this for the edit/update actions.

products_controller.rb

def edit
   @product = Product.find_by_id(params[:id])    
end

def update
  if @product.update_attributes(params[:product])
    flash[:success] = "Product updated"
    redirect_to @product
  else
    render 'edit'
  end
end

编辑

请参阅通过 Rails 中的 link_to 更新字段了解如何操作这使用 link_to 而不是表单.

See Update field through link_to in Rails for how to do this using link_to instead of a form.

推荐答案

尝试

<%= f.hidden_field :parent_id, value: nil %>

代替

<%= f.hidden_field parent_id: nil %>

并确保 parent_id 在模型的 attr_accessible 列表中.

And make sure parent_id is in attr_accessible list of the model.

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