如何从Rails中的另一个控制器获取帖子的ID？

Question

The main of my web is home/index.

And I want to add the contents of the posts controller to the main. I would like to create a link from home/index to posts/show. Also I am using scaffold.

But I am getting the error Could not find Post with 'id' = .

What can I do?

home_controller.rb

  def index
    @post = Post.new

    @posts = Post.find(params[:id])
  end

posts_controller.rb

class PostsController < ApplicationController
  before_action :set_post, only: [:show, :edit, :update, :destroy]

  # GET /posts
  # GET /posts.json
  def index
    @posts = Post.find(params[:id])
  end

  # GET /posts/1
  # GET /posts/1.json
  def show
  end

  # GET /posts/new
  def new
    @post = Post.new
  end


  # GET /posts/1/edit
  def edit
  end

  # POST /posts
  # POST /posts.json
  def create
    @post = Post.new(post_params)

    respond_to do |format|
      if @post.save
        format.html { redirect_to @post, notice: 'Post was successfully created.' }
        format.json { render :show, status: :created, location: @post }
      else
        format.html { render :new }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /posts/1
  # PATCH/PUT /posts/1.json
  def update
    respond_to do |format|
      if @post.update(post_params)
        format.html { redirect_to @post, notice: 'Post was successfully updated.' }
        format.json { render :show, status: :ok, location: @post }
      else
        format.html { render :edit }
        format.json { render json: @post.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /posts/1
  # DELETE /posts/1.json
  def destroy
    @post.destroy
    respond_to do |format|
      format.html { redirect_to posts_url, notice: 'Post was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

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

    # Never trust parameters from the scary internet, only allow the white list through.
    def post_params
      params.require(:post).permit(:title, :content)
    end
end

index.html.erb (home_controller)

<%= link_to 'Show', post_path(@posts.id) %>

Answer 1

An index action is usually used to represent a collection of items. For example:

def index
  @posts = Post.order(:published_at).all
end

Your index action looks very different though. You're creating a new instance of a Post , and then attempting to lookup a single Post by ID. This combines the role of a new action with a show action. For example:

def new
  @post = Post.new
end

def show
  @post = Post.find(params[:id])
end

If you're using resourceful routing, your route helpers expect you to be using this pattern. Thus, a request to /posts goes to the PostsController#index, and /posts/1 goes to the PostsController#show action with an ID parameter equal to 1 .

In your view, you would link to the index action with posts_path (plural) and the show action with post_path(1) (singular, where 1 is the ID of the Post).

I recommend you review your code and adjust it to fit these best practices / the Rails way and see if you can resolve the error.

Answer 2

And I want to add the contents of the posts controller to the main. I would like to create a link from home/index to posts/show.

Based on this, i believe you want to display all the posts on your home page and also have a link against each post to go to show page for that post.

You can achieve that by doing these simple changes in your home action and its view:

home_controller.rb

def index
  @posts = Post.all # Use pagination, if you have hundreds or thousands of posts
end

home/index.html.erb

<% @posts.each do |post| %>
  <%= post.title %>
  <%= post.other_details %>

  <!-- Link to visit individual post's show page -->
  <%= link_to 'See more', post_path(post) %>
<% end %>