#59 Optimistic Locking

最新推荐文章于 2024-04-11 12:13:15 发布

原创最新推荐文章于 2024-04-11 12:13:15 发布 · 157 阅读

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本文介绍了一种通过乐观锁机制解决两个用户几乎同时尝试更新同一记录时出现的数据覆盖问题。通过在产品模型中增加锁版本字段并进行相应控制器修改，确保了数据更新的准确性。

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When two people attempt to update the same record near the same time, one of the updates will likely be overwritten. You can solve this problem with optimistic locking.

# migrations/011_add_products_lock_version.rb
add_column :products, :lock_version, :integer, :default => 0, :null => false

# products_controller.rb
def update
  @product = Product.find(params[:id])
  if @product.update_attributes(params[:product])
    flash[:notice] = "Successfully updated product."
    redirect_to product_path(@product)
  else
    render :action => 'edit'
  end
rescue ActiveRecord::StaleObjectError
  @product.reload
  render :action => 'conflict'
end
<!-- _form.rhtml -->
<%= f.hidden_field :lock_version %>

<!-- conflict.rhtml -->
<% title "Edit Product Conflict" %>

Someone edited the product the same time you did. Please re-apply your changes to the product.

<h2>Your Submission:</h2>
<pre>
<% params[:product].each do |name, value| %>
  <%=h name.humanize %>: <%=h value %>
<% end %>
</pre>

<h2>Edit Product:</h2>
<% form_for :product, :url => product_path(@product), :html => { :method => :put } do |f| %>
  <%= render :partial => 'form', :locals => { :f => f } %>
  <%= submit_tag 'Resolve' %>
<% end %>