我看到this thread有类似的概念，但我得到了一个相当大的错误，我认为是在我的评论控制器。在该页面上的顶级解决方案是，用户只能提交一个评论每一个职位，但如果他们试图再次评论，它仍然被张贴，只是不是在该用户id。然后，如果他们试图张贴第三个评论，功能性工作（因为第二条评论的user_id是nill），他们不能发表评论。所以，用户总共可以发表2条评论，一条正确地使用他们的user_id，另一条不正确地使用user_id设置为nill。请帮助找到问题！edit：哦，当第二条评论提交时，错误“您的评论无法保存。请确保仅提交有效的输入！”仍然出现。但评论仍然张贴

评论控制器：

class CommentsController < ApplicationController
    before_action :find_post
    before_action :find_comment, only: [:destroy, :edit, :update, :comment_owner]
    before_action :comment_owner, only: [:destroy, :edit, :update]
    before_action :authenticate_user!, except: [:show]

    def new
    end

    def create
        @comment = @post.comments.create(params[:comment].permit(:title, :content))
        @comment.user_id = current_user.id
        if @comment.user_id != nil #Here I tried to check to make sure a post couldn't submit with a nil user_id, it's still submitting
           @comment.save
           redirect_to post_path(@post)
        else
            flash[:notice] = "Your commment could not be saved. Please make sure to submit valid input only!"
            redirect_to post_path(@post)
        end
    end

    def show
        @comments = Comment.find(params[:id])   
    end

    def destroy
        @comment.destroy
        redirect_to post_path(@post)
    end

    def edit
        @comments = Comment.find(params[:id])   

    end

    def update
        if @comment.update(params[:comment].permit(:title, :content))
            redirect_to post_path(@post)
        else

            render 'edit'
        end

    end

    private

    def find_post
        @post = Post.find(params[:post_id])
    end
    def find_comment
        @comment = @post.comments.find(params[:id])
    end

    def comment_owner
        unless current_user.id == @comment.user_id
            flash[:notice] = "Not your comment"
            redirect_to @post
        end
    end

end

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我的评论模型：

class Comment < ActiveRecord::Base
    validates :user_id, uniqueness: { scope: :post_id, message: "You've already made a comment!" }

    belongs_to :post
    belongs_to :user
end

型

用户模型，如果重要：

class User < ActiveRecord::Base

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
  has_many :comments, dependent: :destroy

end

型