具有关系依赖的 Rails 事务
我在 Rails 3 中的事务处理方面遇到了一些麻烦。基本上我有两个模型（项目和会员资格）
@project = Project.new(params[:project])
@project.user = current_user
membership = Membership.new
membership.project = @project
Project.transaction do
begin
@project.save!
membership.save!
rescue
flash[:notice] = "There was an error creating your project."
end
end
我正在创建一个新项目并尝试立即为该项目创建会员资格（会员资格实际上也与用户有关系）型号，n:m）。
现在我正在启动一个事务来保存项目和事务中的成员资格。问题是我遇到了异常：
验证失败：项目不能为空
app/controllers/projects_controller.rb:64:in
block in create'创建'
app/controllers/projects_controller.rb:61:in
第 61 行是 Project.transaction do
I'm having some trouble with transactions in Rails 3. Basically I have two models (Project and Membership)
@project = Project.new(params[:project])
@project.user = current_user
membership = Membership.new
membership.project = @project
Project.transaction do
begin
@project.save!
membership.save!
rescue
flash[:notice] = "There was an error creating your project."
end
end
I am creating a new project and trying to immediately create a membership for the project (membership does actually also have a relation to the a User model, n:m).
Now I'm starting a transaction to save the project and the membership inside the transaction. Problem is that I'm getting an exception:
Validation failed: Project can't be blank
app/controllers/projects_controller.rb:64:in
block in create'create'
app/controllers/projects_controller.rb:61:in
Line 61 is Project.transaction do
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好吧，我自己想出来了。成员资格模型验证 :project_id 是否存在。在将项目保存到事务中之前，我正在设置membership.project。之后，我尝试保存成员资格，但由于项目是在数据库中创建之前设置的，因此 :project_id 为零。
为了修复此代码，我必须像这样重新排列它：
请注意，
@project的分配现在是在项目保存后之后（并且 ID 已自动生成）生成）。OK I figured it out myself. The Membership model validates the presence of :project_id. I am setting membership.project before I save the project inside the transaction. After that I am trying to save the membership, but as the project was set before it was created in the database the :project_id is nil.
In order to fix this code I had to rearrange it like this:
Note that the assignment of
@projectis now after the project has been saved (and an ID has been automatically generated).