AVOID DUPLICATES in sequelize query - mysql

Question

i'm implementing a like system for a project. And I need some help with a query.
Basically i have 2 buttons (upvote and downvote) that call my function and give the id of a thread, the username voting, and the vote ( 1 or -1).
addPositiveorNegativeLikes = function(thread_id, username, vote) {
sequelize.query('INSERT INTO Likes (thread_id, userId, vote, createdAt, updatedAt)
VALUES((?), (SELECT id FROM Users WHERE username=(?)), (?), (?), (?))
ON DUPLICATE KEY UPDATE thread_id=(?), userId=(SELECT id FROM Users WHERE username=(?))',{
replacements: [thread_id, username, vote, new Date(), new Date(), thread_id, username]
})
}
But now in my Likes table althought thread_id and userId ara both primary keys, inserts multiple repeated "Likes".
How I can modify my query so it deletes an existing vote and replaces it for a new one??
Here is my Like model:
'use strict';
module.exports = (sequelize, DataTypes) => {
const Like = sequelize.define('Like', {
id: {
allowNull: false,
autoIncrement: true,
primaryKey: true,
type: DataTypes.INTEGER
},
userId: {
allowNull: false,
primaryKey: true,
type: DataTypes.INTEGER
},
thread_id: {
allowNull: false,
primaryKey: true,
type: DataTypes.INTEGER
},
createdAt: {
allowNull: false,
type: DataTypes.DATE
},
updatedAt: {
allowNull: false,
type: DataTypes.DATE
},
vote: {
type: DataTypes.INTEGER
}
}, {});
Like.associate = function(models) {
// associations can be defined here
};
return Like;
};

Answer 1

Here , what you can do is , create a composite key , with this
userId: {
allowNull: false,
unique:"vote_user" // <------ HERE
type: DataTypes.INTEGER
},
thread_id: {
allowNull: false,
unique:"vote_user" // <------ HERE
type: DataTypes.INTEGER
},
NOTE :
// Creating two objects with the same value will throw an error. The unique property can be either a
// boolean, or a string. If you provide the same string for multiple columns, they will form a
// composite unique key.
uniqueOne: { type: Sequelize.STRING, unique: 'compositeIndex' },
uniqueTwo: { type: Sequelize.INTEGER, unique: 'compositeIndex' },
And then create it like :
Like.create({ userId : 1 , thread_id : 1 }).then(data => {
// success
}).catch(err => {
// error if same data exists
})
// <--- this will check that if there any entry with userId 1 and thread_id 1 ,
// if yes , then this will throw error
// if no then will create an entry for that
Note :
Never never run raw query , like you have did in your code sample , always use the model to perform CRUD , this way you can utilize all
the features of sequelizejs