mysql - 在 sequelize 查询中避免重复

Question

我正在为一个项目实现类似的系统。我需要一些查询帮助。

基本上我有 2 个按钮(upvote 和 downvote)调用我的函数并给出线程的 id、用户名投票和投票(1 或 -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]
 }) 
}

但现在在我的 Likes 表中虽然 thread_id 和 userId 都是主键，但插入了多个重复的“Likes”。

我如何修改我的查询以删除现有投票并将其替换为新投票？

这是我的 Like 模型:

'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

在这里，你可以做的是，创建一个复合键，用这个

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' },

然后像这样创建它:

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