sequelize.js association accessor - node.js

Question

I made API server with Node.js
Also I use sequelize.js(version 4) for communicate with MySQL.
My table structure is here.
[Article]
no(PK)
subject
content
created_at
updated_at
[Comment]
no(PK)
content
created_at
updated_at
article_no(FK to Article)
[index.controller.js]
import { Article, Comment } from '../model/model';
export const index = (req, res) => {
res.send('controller index');
};
export const getArticle = (req, res) => {
try {
Article.all()
.then(article => {
res.status(200).json({status: true, result: article});
});
} catch(e) {
res.status(500).json({status: false, result: "get article fail"});
}
}
export const addArticle = (req, res) => {
const { subject, content } = req.body;
try {
Article.create({
subject: subject,
content: content
})
res.status(200).json({status: true, result: "article write success"});
} catch(e) {
res.status(500).json({status: false, result: "article fail"});
}
}
export const getComment = (req, res) => {
try {
Comment.all()
.then(comment => {
res.status(200).json({status: true, result: comment})
});
} catch(e) {
res.status(500).json({status: false, result: "get comment fail"});
}
}
export const addComment = (req, res) => {
const { content, article_no } = req.body;
try {
Comment.create({
content: content,
article_no: article_no
})
.then(() => res.status(200).json({status: true, result: "comment write success"}))
} catch(e) {
console.log(e);
res.status(500).json({status: false, result: "comment fail"});
}
}
[index.js]
import express from 'express';
import { index, getArticle, getComment,addArticle, addComment } from './index.controller';
const router = express.Router();
router.get('/', index);
router.get('/article', getArticle);
router.post('/article', addArticle);
router.get('/comment', getComment);
router.post('/comment', addComment);
export default router;
[model.js]
import Sequelize from 'sequelize';
const sequelize = new Sequelize('db', 'id', 'pw', {
host: '127.0.0.1',
dialect: 'mysql'
})
export const Article = sequelize.define('article', {
no: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
subject: {
type: Sequelize.STRING,
allowNull: false
},
content: {
type: Sequelize.STRING,
allowNull: false
}
}, {
freezeTableName: true,
underscored: true
})
export const Comment = sequelize.define('comment', {
no: {
type: Sequelize.INTEGER,
primaryKey: true,
autoIncrement: true
},
content: {
type: Sequelize.STRING,
allowNull: false
}
}, {
freezeTableName: true,
underscored: true
})
Article.hasMany(Comment, {as: 'Comments'}); // association
Comment.belongsTo(Article); // association
sequelize.sync({
force: false
});
Because of association(hasMany, belongsTo), article_no column will be added to Comment table.
Refer to this document, http://docs.sequelizejs.com/manual/tutorial/associations.html#one-to-many-associations-hasmany-
It says that Instances of Project will get the accessors getWorkers and setWorkers.
In my case, it will be getComments and setComments.
But I don't know exactly how can I get all the comments related articles with using accessor.
Current output is here. (If I connect to GET /article)
{
"status":true,
"result":[
{
"no":1,
"content":"comment test",
"created_at":"2018-07-18T05:00:45.000Z",
"updated_at":"2018-07-18T05:00:45.000Z",
"article_no":1
}
]
}
Desired output is here
{
"status":true,
"result":[
{
"no":1,
"content":"comment test",
"created_at":"2018-07-18T05:00:45.000Z",
"updated_at":"2018-07-18T05:00:45.000Z",
"article_no":1,
"comments": [
// related comments here!
]
}
]
}
Thanks.

Answer 1

When you want to join another model you should use include in your query
User.findAll({
include: [
{ model: Profile, required: true // inner join }
],
limit: 3
});
Check out the Sequelize model usage docs.
To access the comments with accessors you will need do something like this:
const articles = await Article.all();
articles.forEach(article => {
const comments = await article.getComments();
})
The idea behind is that each article sequelize object will have the accessor getComments but internally what it does when you execute getComments it makes a new request to the database with the prepopulated articleId in the comments where query. This is called lazy loading because you can load the data when you need it. But that is not your case.
For the desired output I suggest to use the include method cause it will make a single request to the database.