Node.js/Expressで楽々Webアプリ開発（Vol.56掲載）

著者：しょっさん

プログラミング言語「JavaScript」の実行環境「Node.js」と「Express」フレームワークを使って、基本となるWebアプリの開発手法を習得しましょう。第2回は「蔵書管理アプリケーション」を作成しながら、少し複雑なデータベースを扱う方法を紹介します。

シェルスクリプトマガジン Vol.56は以下のリンク先でご購入できます。

'use strict';
module.exports = (sequelize, DataTypes) => {
  var Library = sequelize.define('Library', {
    book_title: DataTypes.STRING,
    author: DataTypes.STRING,
    publisher: DataTypes.STRING,
    image_url: DataTypes.STRING(2048)
  },
  {
    underscored: true,
  });
  Library.associate = function (models) {
    // 参照制約を示すときは、ここに記述。今回は1:nなので'hasMany'を使用
    Library.hasMany(models.Comment, { foreignKey: 'book_id' });
  };
  return Library;
};

'use strict';

module.exports = (sequelize, DataTypes) => {

var Library = sequelize.define('Library', {

book_title: DataTypes.STRING,

author: DataTypes.STRING,

publisher: DataTypes.STRING,

image_url: DataTypes.STRING(2048)

{

underscored: true,

});

Library.associate = function (models) {

// 参照制約を示すときは、ここに記述。今回は1:nなので'hasMany'を使用

Library.hasMany(models.Comment, { foreignKey: 'book_id' });

};

return Library;

};

book_id: {
  type: Sequelize.INTEGER,
  allowNull: false,
  foreignKey: true,
  references: {
    model: 'Libraries',
    key: 'id',
  },
  onUpdate: 'RESTRICT',
  onDelete: 'RESTRICT',
},

book_id: {

type: Sequelize.INTEGER,

allowNull: false,

foreignKey: true,

references: {

model: 'Libraries',

key: 'id',

onUpdate: 'RESTRICT',

onDelete: 'RESTRICT',

get_book: function (book_id) {
  return libraries.findOne({
    where: {
      id: book_id
    },
    include: [{
      model: comments,
      required: false
    }]
  });
},

get_book: function (book_id) {

return libraries.findOne({

where: {

id: book_id

include: [{

model: comments,

required: false

}]

});

{ id: 1,
  book_title: 'title',
  author: 'しょっさん',
  publisher: 'USP研究所',
  image_url: 'http://example.com/',
  created_at: '2018-08-09T00:49:22.382Z',
  updated_at: '2018-08-09T00:49:22.934Z',
Comments:
  [ { id: 1,
      comment: '#1へのコメント#1',
      book_id: 1,
      created_at: '2018-08-09T00:49:22.401Z',
      updated_at: '2018-08-09T00:49:22.401Z' },
    { id: 2,
      comment: '#1へのコメント#2',
      book_id: 1,
      created_at: '2018-08-09T00:49:22.401Z',
      updated_at: '2018-08-09T00:49:22.401Z' },
    { id: 3,
      comment: '#1へのコメント#3',
      book_id: 1,
      created_at: '2018-08-09T00:49:22.401Z',
      updated_at: '2018-08-09T00:49:22.401Z' } ] }

{ id: 1,

book_title: 'title',

author: 'しょっさん',

publisher: 'USP研究所',

image_url: 'http://example.com/',

created_at: '2018-08-09T00:49:22.382Z',

updated_at: '2018-08-09T00:49:22.934Z',

Comments:

[ { id: 1,

comment: '#1へのコメント#1',

book_id: 1,

created_at: '2018-08-09T00:49:22.401Z',

updated_at: '2018-08-09T00:49:22.401Z' },

{ id: 2,

comment: '#1へのコメント#2',

book_id: 1,

created_at: '2018-08-09T00:49:22.401Z',

updated_at: '2018-08-09T00:49:22.401Z' },

{ id: 3,

comment: '#1へのコメント#3',

book_id: 1,

created_at: '2018-08-09T00:49:22.401Z',

updated_at: '2018-08-09T00:49:22.401Z' } ] }

  get_contents: function () {
    return libraries.findAll({
      attributes: ['id', 'book_title', 'author','publisher',[models.sequelize.fn('COUNT',models.sequelize.col('Comments.book_id')), 'cnt']],
      group: ['Library.id'],
      raw: true,
      subQuery: false,
      limit: 10,
      include: {
        model: models.Comment,
        attributes: []
      },
    });
  },

get_contents: function () {

return libraries.findAll({

attributes: ['id', 'book_title', 'author','publisher',[models.sequelize.fn('COUNT',models.sequelize.col('Comments.book_id')), 'cnt']],

group: ['Library.id'],

raw: true,

subQuery: false,

limit: 10,

include: {

model: models.Comment,

attributes: []

});