Object property is filled when shown but undefined when accessed. Nodejs Sequelize - sql

Question

I am performing this raw sql query
SELECT postId, users.id as userId,users.firstName,users.lastName,users.avatar,COUNT(postId) as
numOfLikes,body
FROM posts
INNER JOIN likes ON likes.postId = posts.id
INNER JOIN users ON users.id = posts.userId
GROUP BY postId
ORDER BY postId DESC
through nodeJs sequelize ORM
Posts.findAll({
attributes: ['id','body','createdAt', [db.fn('count', db.col('likes.postId')), 'numOfLikes']],
include: [{ attributes: [], model: Likes,required:true, },{model:Users,required:true}],
group: ['id'],
order: [['id', 'DESC']]
})
I receive everything as it should be but cannot access numOfLikes object property (undefined)
{
"id": 18,
"body": "This show was organized.",
"createdAt": "2021-03-06T23:55:44.000Z",
"numOfLikes": 5,
"user": {
"id": 73,
"firstName": "Paolo",
"lastName": "Jovovic",
"email": "dzonnna#gmail.com",
"email_verified": "1",
"password": "$2b$10$6fLwPfuLP8Jfp7em0iqBm.YhznDut8AWOmUPynqecfd9YMvZBMaXq",
"google_id": null,
"avatar": "1_aZF6_EToO4T3ZeHXfgF-Vg.png",
"role": "0",
"createdAt": "2021-02-28T22:30:42.000Z",
"updatedAt": "2021-03-01T23:59:21.000Z"
}
}

Answer 1

I had this same issue - I was selecting certain attributes and the query was working correctly.
const books = await Book.findAll({
where: {status_id: [status[0].id, status[1].id]},
attributes: ["id", "cover", "title", "status_id", "created_at"],
order: [["_id", "DESC"]],
})
the object showed the value but when i tried to access it, it was always undefined.
dataValues: {
id: '9beb341c-a0fa-489d-8a32-c9ec28f0ab16',
cover: 'cover_500.jpg',
title: 'birth',
status_id: '8a5b8c46-b5ac-477a-b1c5-ca2210399e6c',
created_at: 2022-10-16T02:10:32.000Z
},
I should point out here that i've changed the name of createAt in the model
createdAt: {
field: "created_at",
type: Sequelize.DATE,
},
when trying to access the value with book.create_at or book.createAt both come back as undefined even though they are clearly on the object. this is a very strange behavior. since they are in the datavalues they should be accessible.
when I remove the attributes selection column and just return everything for the row, it magically works.
so the issue is either,
I changed the name in the model and there is some kind of issue / error in sequalize
There is just some kind of issue / error with sequalize access the datavalue
either way, you can grab the whole row and only return / build your object out of the columns you desire.
I switched the attributes to
attributes: ["id", "cover", "title", "status_id", "createdAt"],
and it is now letting me access the field with createdAt but still not created_at so the issue appears to be the renaming of the field along with the selection of attributes.
hope this helps someone until they can fix this.

Answer 2

Posts.findAll({
attributes: ['id', 'body', 'createdAt', [db.fn('count', db.col('likes.postId')), 'numOfLikes']],
include: [{ attributes: [], model: Likes, required: true, }, { model: Users, required: true }],
group: ['id'],
order: [['id', 'DESC']]
}).then(postList => {
postList = JSON.parse(JSON.stringify(postList)) // This is important
postList.forEach(post => {
// access post
console.log(post, post.users)
});
})