【Rails API + Vue】Active Storageを使って画像をアップロード・表示する

rails-vue-file-uploader-sample
└── backend   # Railsプロジェクト
└── frontend  # Vueプロジェクト

$ mkdir rails-vue-file-uploader-sample
$ cd rails-vue-file-uploader-sample
$ rails _6.0_ new backend --api
$ cd backend
$ rails db:create

$ rails active_storage:install
$ rails db:migrate

$ rails g model post title:string image:attachment
$ rails db:migrate

class Post < ApplicationRecord
  has_one_attached :image
end

$ rails g controller posts

class PostsController < ApplicationController
  def index
    render json: Post.all
  end

  def create
    post = Post.new(post_params)
    if post.save
      render json: post
    else
      render json: post.errors, status: 422
    end
  end

  def destroy
    post = Post.find(params[:id])
    post.destroy!
    render json: post
  end

  private

  def post_params
    params.permit(:title, :image)
  end
end

Rails.application.routes.draw do
  scope :api do
    resources :posts, only: [:index, :create, :destroy]
  end
end

class Post < ApplicationRecord
  include Rails.application.routes.url_helpers

  has_one_attached :image

  def image_url
    # 紐づいている画像のURLを取得する
    image.attached? ? url_for(image) : nil
  end
end

class PostsController < ApplicationController
  def index
    render json: Post.all, methods: [:image_url]  # ここを変更
  end

  def create
    post = Post.new(post_params)
    if post.save
      render json: post, methods: [:image_url]  # ここを変更
    else
      render json: post.errors, status: 422
    end
  end

  def destroy
    post = Post.find(params[:id])
    post.destroy!
    render json: post
  end

  private

  def post_params
    params.permit(:title, :image)
  end
end

Rails.application.configure do
  ...

  # これを追加
  Rails.application.routes.default_url_options[:host] = 'localhost'
  Rails.application.routes.default_url_options[:port] = 3000
end

Rails.application.config.middleware.insert_before 0, Rack::Cors do
  allow do
    origins 'http://localhost:8080'

    resource '*',
      headers: :any,
      methods: [:get, :post, :put, :patch, :delete, :options, :head]
  end
end

$ cd rails-vue-file-uploader-sample
$ vue create frontend
$ cd frontend

? Please pick a preset: Manually select features
? Check the features needed for your project: Vuex, Linter
? Pick a linter / formatter config: Prettier
? Pick additional lint features: Lint on save
? Where do you prefer placing config for Babel, ESLint, etc.? In dedicated config files
? Save this as a preset for future projects? No

$ npm install --save axios

import axios from "axios";

const apiUrlBase = "http://localhost:3000/api/posts";
const headers = { "Content-Type": "multipart/form-data" };

const state = {
  posts: []
};

const getters = {
  posts: state => state.posts.sort((a, b) => b.id - a.id)
};

const mutations = {
  setPosts: (state, posts) => (state.posts = posts),
  appendPost: (state, post) => (state.posts = [...state.posts, post]),
  removePost: (state, id) =>
    (state.posts = state.posts.filter(post => post.id !== id))
};

const actions = {
  async fetchPosts({ commit }) {
    try {
      const response = await axios.get(`${apiUrlBase}`);
      commit("setPosts", response.data);
    } catch (e) {
      console.error(e);
    }
  },
  async createPost({ commit }, post) {
    try {
      const response = await axios.post(`${apiUrlBase}`, post, headers);
      commit("appendPost", response.data);
    } catch (e) {
      console.error(e);
    }
  },
  async deletePost({ commit }, id) {
    try {
      axios.delete(`${apiUrlBase}/${id}`);
      commit("removePost", id);
    } catch (e) {
      console.error(e);
    }
  }
};

export default {
  namespaced: true,
  state,
  getters,
  mutations,
  actions
};

import Vue from "vue";
import Vuex from "vuex";
import posts from "./modules/posts";

Vue.use(Vuex);

export default new Vuex.Store({
  modules: {
    posts
  }
});

<template>
  <div>
    <h2>PostForm</h2>
    <section>
      <label for="title">title: </label>
      <input type="text" name="title" v-model="title" placeholder="title" />
    </section>
    <section>
      <label for="image">image: </label>
      <input type="file" id="image" name="image" accept="image/png,image/jpeg" @change="setImage" />
    </section>
    <section>
      <button type="submit" @click="upload" :disabled="title === ''">upload</button>
    </section>
  </div>
</template>

<script>
import { mapActions } from "vuex";

export default {
  name: "PostForm",
  data: () => ({
    title: "",
    imageFile: null
  }),
  methods: {
    ...mapActions("posts", ["createPost"]),
    setImage(e) {
      e.preventDefault();
      this.imageFile = e.target.files[0];
    },
    async upload() {
      let formData = new FormData();
      formData.append("title", this.title);
      if (this.imageFile !== null) {
        formData.append("image", this.imageFile);
      }
      this.createPost(formData);
      this.resetForm();
    },
    resetForm() {
      this.title = "";
      this.imageFile = null;
    }
  }
};
</script>

<template>
  <div>
    <h2>PostList</h2>
    <div v-for="post in posts" :key="post.id">
      <h3>{{ post.title }}</h3>
      <img :src="post.image_url" />
      <br />
      <button type="submit" @click="del(post.id)">delete</button>
    </div>
  </div>
</template>

<script>
import { mapActions, mapGetters } from "vuex";

export default {
  name: "PostList",
  created() {
    this.fetchPosts();
  },
  computed: {
    ...mapGetters("posts", ["posts"])
  },
  methods: {
    ...mapActions("posts", ["fetchPosts", "deletePost"]),
    del(id) {
      this.deletePost(id);
    }
  }
};
</script>

<template>
  <div id="app">
    <PostForm />
    <PostList />
  </div>
</template>

<script>
import PostForm from "./components/PostForm.vue";
import PostList from "./components/PostList.vue";

export default {
  name: "App",
  components: {
    PostForm,
    PostList
  }
};
</script>