[RAILS] Story of implementing update function in form object

What did you do

I am making an app that imitates Instagram. As shown below, there is a post linked to the user, and it has a structure that has multiple images.

It was nice to have created a new post form using form object with this structure,

▼ Implemented in this article The story of saving an image with carrierwave in a nested form using a form object.

From there, I had a lot of trouble creating the update form, so I'll put together the code I wrote.

The execution environment is as follows.

• Rails 5.2.3
• Ruby 2.6.0

Also, I use carrier wave to post images.

Code I wrote

I will introduce the code I actually wrote and add an explanation to it.

controller

The instance created by form object is passed to the view in the form of @post_form.

controllers/posts_controller.rb

class PostsController < ApplicationController
  before_action :require_login, only: %i(new edit)
  before_action :set_post, only: %i(edit update)

  def new
    @post_form = PostForm.new(current_user)
  end

  def create
    @post_form = PostForm.new(current_user, post_params, post: Post.new)
    if @post_form.save!
      redirect_to root_path
      flash[:success] = "Posted"
    else
      flash.now[:danger] = "Posting failed"
      render :new
    end
  end

  def edit
    @post_form = PostForm.new(current_user, post: @post)
  end

  def update
    @post_form = PostForm.new(current_user, post_params, post: @post)
    if @post_form.save!
      redirect_to root_path
      flash[:success] = "I edited the post"
    else
      flash.now[:danger] = "Post edit failed"
      render :edit
    end
  end

  private

  def post_params
    params.require(:post).permit(:body, photoes: [])
  end

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

view

The view receives an instance in the form model: @post_form. (Actually, the same partial was used for new and edit, so @ post_form was made a local variable called form.)

Ruby:views/posts/_post_form.html.slim

= form_with model: @post_form, local: true do |f|
  .form-group
    = f.label :photoes, t('activerecord.models.images.photo'), class: 'bmd-label-floating"'
    = f.file_field :photoes, multiple: true, class: 'form-control mb-1'
  .form-group
    = f.label :body, t('activerecord.models.posts.body'), class: 'bmd-label-floating"'
    = f.text_field :body, class: 'form-control'
  = f.submit 'register', class: 'btn btn-raised btn-success'

form object

forms/post_form.rb

class PostForm
  include ActiveModel::Model

  attr_accessor :body, :photoes, :user
  validates :body, presence: true

  def initialize(user, params = {}, post: '')
    @post ||= Post.new
    @post.assign_attributes({user: user, body: params[:body]})
    super(params)
  end

  def to_model #I will explain
    @post
  end

  def save!
    return false if invalid?
    if photoes
      photoes.each do |photo|
        @post.images.build(photo: photo).save!
      end
    end

    @post.save! ? true : false
  end
end

The point is that to_model makes the form object behave like a model. What this means is that the form object is a" just class "different from the ActiveRecord model, so the routing path that Rails guesses by default on new / edit forms is applied well. not.

So by making to_model think of form object as if it were a model, Rails' default routing can be used with form object as well.

The implementation around here was very helpful to this article.

Rails: Separate validation from model using Form Object and # to_model (translation)

[Unresolved] The issue that was occurring in the uodate action.

However, even with this implementation, for the update action, I tried to access POST'posts /: id' and did not follow the routing well.

On the other hand, I was able to find the following two solutions on the net.

-Overwrite the URL of form. -Change the action to apply using delegate.

In my case, the former was too verbose in code and the latter couldn't work well, so I had no choice but to rewrite routes.rb as follows.

config/routes.rb

post '/posts/:id', to: 'posts#update'

I can't deny the feeling of a monkey patch, but this time I'm happy with this ... I would like to refactor it when my ability improves a little more.

Impressions etc.

In my work implementation, the update method of the form object didn't take the time to implement it and gave up, but now I have a clue for the implementation: relaxed: I want to improve my knowledge so that I can share it within the company: sparkles: