Question

当我试图在我的应用上实现一种帖子功能时，我碰到了这个错误，这是我的头脑。

ArgumentError in Projects#show
first argument in form cannot contain nil or be empty
<%= form_for(@micropost, html: { multipart: true }) do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">

Micropost控制器。

class MicropostsController < ApplicationController
  before_action :logged_in_user, only: [:create, :destroy]
  before_action :correct_user,   only: [:create, :destroy]

  def create
    @project = Project.find(params[:project_id])
    @micropost = @project.microposts.build(micropost_params)
    @micropost.user.id = current_user.id
    if @micropost.save
      flash[:success] = "Micropost created!"
      redirect_to @project
    else
      @feed_items = []
      render 'static_pages/home'
    end
  end

Micropost.model

class Micropost < ApplicationRecord
  belongs_to :user 
  belongs_to :project

  default_scope -> { order(created_at: :desc) }
  mount_uploader :picture, PictureUploader

  validates :user_id , presence: true
  validates :project_id, presence: true
  validate  :picture_size

  #...
end

来自routes.rb的摘录

resources :users do
  member do
    get :following, :followers
  end
end
resources :projects do
  resources :microposts
end

和表格。

<%= form_for(@micropost, html: { multipart: true }) do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_area :content, placeholder: "Compose new micropost..." %>
    <%= hidden_field_tag :user_id, :value => current_user.id %>
  </div>
  <%= f.submit "Post", class: "btn btn-primary" %>
    <span class="picture">
    <%= f.file_field :picture, accept: 'image/jpeg,image/gif,image/png' %>
  </span>
<% end %>

有什么想法吗？

-------更新1 ---------

项目控制器

class ProjectsController < ApplicationController
  before_action :logged_in_user, only: [:index, :show, :create, :destroy]
  before_action :correct_user || :admin_user  , only: :destroy

  def index
  end

  def show
    @project = Project.find(params[:id])
  end

  def new
    @project = Project.new
  end

  def create
    @project = current_user.projects.build(project_params)
    if @project.save
      flash[:success] = "Project Created"
      redirect_to @project
    else
      render 'new'
    end
  end

  def destroy
    Project.find(params[:id]).destroy
    flash[:success] = "Project Deleted"
    redirect_to request.referrer || root_url
  end
end

------更新2 --------

class ProjectsController < ApplicationController
before_action :logged_in_user, only: [:index, :show, :create, :destroy]
before_action :correct_user, only: :destroy
before_action :admin_user, only: :destroy


def show
    @project = Project.find(params[:id])
  @micropost = @project.microposts.build
  #I cannot have them both defined at the same time so how do I go about this 
  @micropost = @project.microposts.paginate(page: params[:page])
end

def new
    @project = Project.new
end

def create
    @project = current_user.projects.build(project_params)
    if @project.save
        flash[:success] = "Project Created"
        redirect_to @project
    else
      render 'new'
    end
end

def destroy
    Project.find(params[:id]).destroy
    flash[:success] = "Project Deleted"
    redirect_to request.referrer || root_url
  end

private

def project_params
    params.require(:project).permit(:name,:category,:picture)
end

def correct_user
  @project = current_user.projects.find_by(id: params[:id])
  redirect_to root_url if @project.nil?
end
end

Answer 1

好的，问题是，

在项目控制器展示操作中，您正在初始化@project但不是@micropost，这将是nil

并且我认为您在Projects#show中渲染相同的部分，它正在尝试为@micropost呈现表单，在这种情况下为nil

<%= form_for(@micropost, html: { multipart: true }) do |f| %>

应该是

<%= form_for(@project, html: { multipart: true }) do |f| %>

表单中的第一个参数不能包含nil或为空

1 个答案: