Question

我正在尝试在我的数据库中实现某种唯一性，如果它已经在数据库中，则可以选择替换当前值。

我的表格似乎是

t.integer  "task_id"
t.integer  "accessor_id"
t.integer  "access_owner"
t.boolean  "access_rights"

我想检查一下如果有一个条目有task_id，accessor_id和access_owner而不是更新access_right，如果没有一个创建这样的条目

我当前的创建方法和新方法是

class AccessorsController < ApplicationController
 def new
      @accessor = Accessor.new
      @task_id = params[:task_id]
  end


  def create
    @accessor = Accessor.new(accessor_params)
    @user = User.where(email: params[:accessor][:accessor_id]).first
    @accessor.accessor_id = @user.id    
    @accessor.access_owner = current_user.id
    respond_to do |format|
      if @accessor.save
        format.html { redirect_to Task, notice: 'User was successfully created.' } #
        format.json { render action: 'show', status: :created, location: Task }#
      else
        format.html { render action: 'new' } #
        format.json { render json: @accessor.errors, status: :unprocessable_entity }#
      end
    end
  end

我尝试了以下

@accessor = Accessor.where("access_owner = ? AND accessor_id = ? AND task_id = ?", current_user.id, User.where(email: params[:accessor][:accessor_id]).first,params[:task_id]).first || Accessor.new(accessor_params)

但它无效

Answer 1

您可以使用find_or_initialize_by..方法：

@accessor = Accessor.find_or_initialize_by_task_id_and_accessor_id_and_access_owner(params[:task_id], params[:accessor_id], params[:access_owner])

@accessor.update_attributes(
   :access_rights => params[:access_rights]
)

如何实现if条目存在覆盖rails数据库

1 个答案: