Rails表单参数未保存

Question

我是Ruby on Rails的新手，我在脚手架控制器上苦苦挣扎。 我做了一个嵌套的资源，将我的评论放在帖子中。

class Post < ActiveRecord::Base
  validates :name,  :presence => true
  validates :title, :presence => true, :length => { :minimum => 5 }
  has_many :comments
end

class Comment < ActiveRecord::Base
  validates :commenter, :presence => true
  validates :body, :presence => true     
  belongs_to :post
end

控制器的简化版本是

class CommentsController < ApplicationController
  before_action :set_comment, only: [:show, :edit, :update, :destroy]

  # omited new, index, show... 

  # POST /comments
  # POST /comments.json
  def create
    post = Post.find(params[:post_id])
    @comment = post.comments.create(params[:comment].permit(:name, :title, :context))

    respond_to do |format|
      if @comment.save
        format.html { redirect_to([@comment.post, @comment], notice: 'Comment was successfully created.') }
        format.json { render action: 'show', status: :created, location: @comment }
      else
        format.html { render action: 'new' }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /comments/1
  # PATCH/PUT /comments/1.json
  def update
    post = Post.find(params[:post_id])
    @comment = post.comments.find(params[:comment])
    respond_to do |format|
      if @comment.update(comment_params)
        format.html { redirect_to @comment, notice: 'Comment was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @comment.errors, status: :unprocessable_entity }
      end
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_comment
      @comment = Comment.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def comment_params
      params.require(:comment).permit(:commenter, :body, :post)
    end
end

当我填写表格时，出现以下异常：

有2个错误禁止保存此评论：评论者不能为空正文不能为空

我尝试了本指南，但我认为它与Rails 4不兼容。

Answer 1

看来您在create操作中明确permitting不同的属性集。

您应该像在update操作中所做的那样，将您的create操作更新为使用comment_params 。 之所以成为您的Comment ，绝对是因为期望Commenter和Body而不是您在create动作中允许的:name, :title, :context 。

将controller的create操作更新为：

  # POST /comments
  # POST /comments.json
  def create
    ...
    @comment = post.comments.create(comment_params)
    ...
  end

Answer 2

您正在从Post params属性中读取（ :name, :title, :context ），但是您需要阅读Comments属性（ :commenter, :body ）

替换为：

@comment = post.comments.create(params[:comment].permit(:name, :title, :context))

与

@comment = post.comments.create(params[:comment].permit(:commenter, :body))

或者，更好的是：

@comment = post.comments.create(comment_params)