用户在使用 Sequelize 之前是否喜欢 post

Question

目前，当用户喜欢 post 时，该喜欢的记录会添加到我的喜欢 table 中，其中包含用户 ID 和 postId。

现在，当用户查看 post 时，我想确定他们之前是否喜欢 post。我明白要这样做，我需要在调用 post 信息时在 get 请求中确定这一点。

当我要求 post 信息时，我需要检查 Likes table 以获取当前用户的 userId 和当前 postId 的记录 post。如果存在，那么我需要 return 一个名为 isLiked 的参数并将其设置为 true，如果不存在，则 isLiked=false。

这是我的 Post 模型：

id: {
  type: Sequelize.INTEGER,
  primaryKey: true,
  autoIncrement: true,
},
title: {
  type: Sequelize.STRING,

},
userId: {
  type: Sequelize.INTEGER,
},
likesCount:{
  type:Sequelize.INTEGER,
  defaultValue:0,
  validate: {
            min: 0,
        }
},

这是我的点赞模型：

id: {
allowNull: false,
autoIncrement: true,
primaryKey: true,
type: Sequelize.INTEGER,
 },
 PostId: {
type: Sequelize.INTEGER,
references: {
  model: "Post",
  key: "id",
},
 },
 userId: {
type: Sequelize.INTEGER,
references: {
  model: "User",
  key: "id",
},
 },

这是我的用户模型：

id: {
  type: Sequelize.INTEGER,
  primaryKey: true,
  autoIncrement: true,
},
name: {
  type: Sequelize.STRING,
 },

这是我的联想：

User.hasMany(Post, { foreignKey: "userId" });
Post.belongsTo(User, { foreignKey: "userId" });

Post.hasMany(Likes, { foreignKey: "PostId", targetKey: "id" });
Likes.belongsTo(Post, { foreignKey: "PostId", targetKey: "id" });

User.hasMany(Likes, { foreignKey: "userId", targetKey: "id" });
Likes.belongsTo(User, { foreignKey: "userId", targetKey: "id" });

更新

我一直在研究并发现，因为我正在使用 JWT 中间件来签署我的用户令牌，并且我目前正在检查当前用户是否有类似 table 的任何记录，我尝试了以下但有人可以告诉我这种方法是否正确吗？

 router.get("/", async (req, res) => {
    const posts = await Post.findAll({
   order: [["createdAt", "DESC"]],
   include: [
  { model: Post_Image, attributes: ["id", "images"] },
  { model: Likes, attributes: ["id", "PostId", "userId"] },
  ],
  });

 if (!posts) return res.status(404).send();

 const baseUrl = config.get("assetsBaseUrl");

 const plainPosts = posts.map((x) => x.get({ plain: true }));
 const resultPosts = [];
  for (const post of plainPosts) {

 let isLiked = false;
 let like = await Likes.findOne({
where: {
[Op.and]: [{ PostId: post.id) }, { userId: 
req.user.id }],

  },
 });

if (like) isLiked = true;

const { Post_Images, ...postAttributes } = post;
const IMAGES = Post_Images.map((postImage) => ({
  url: `${baseUrl}${postImage.images}_full.jpg`,
  thumbnailUrl: `${baseUrl}${postImage.images}_thumb.jpg`,
}));
resultPosts.push({ ...postAttributes, images: IMAGES, isLiked 
});
}

res.send( resultPosts );

 });

Answer 1

除非您想覆盖某些内容，否则您不需要指定所有字段，否则 Sequelize 可以为您生成大部分列。

const User = sequelize.define(
  'user',
  {
    name: {
      type: Sequelize.STRING,
    },
  },
  { /* options */ }
);

const Post = sequelize.define(
  'post',
  {
    title: {
      type: Sequelize.STRING,
    },
  },
  { /* options */ }
);

// the join table so you can reference it, but doesn't need any columns including primary key (unless you want to a "super join")
const Likes = sequelize.define(
  'likes',
  {}, // no columns here
  { /* options */ }
);

创建模型之间的关联将自动创建大部分外键字段。在 Likes 关系上使用 through 关键字使其成为多对多关系。


// Users can have many Posts
User.hasMany(Post);

// Posts belong to one User
Post.belongsTo(User);

// Users can like more than one Post through the `likes` join table
User.hasMany(Post, { as: 'likes', through: 'likes' });

// Posts can be liked by more than one User through the `likes` join table
Post.hasMany(User, { as: 'likes', through: 'likes' });

不需要存储点赞数，因为可以通过join table.

汇总

// Get the 'likes' count for a Post, instead of saving it on the post
const posts = await Post.findAll({
  attributes: {
    include: [
      [sequelize.fn('COUNT', sequelize.col('likes.userId')), 'likesCount'],
    ],
  },
  include: [
    {
      model: User,
      as: 'likes',
      though: 'likes',
      attributes: [],
      required: false,
    },
  ],
});

// `posts` will be an array of Post instances that have a likesCount property
posts.forEach((post) => {
  console.log(`The post ${post.title} has ${post.likesCount} likes.`);
});

对于个人（或多个）Post，您可以通过 post 获得喜欢它的用户列表（或使用 Like 模型及其关系） .


// Get the user 'likes' for a Post
const post = await Post.findByPk(postId, {
  include: [
    {
      model: User,
      as: 'likes',
      though: 'likes',
      required: false,
    },
  ],
});

post.likes.forEach((like) => {
  console.log(`The user ${like.name} has liked the post ${post.title}.`);
});

Answer 2

你不需要再次请求Like，你已经得到了所有post的赞：

for (const post of plainPosts) {
 // check if we have any like among posts' likes that is made by a certain user
 const isLiked = post.Likes.some(x => x.userId === req.user.id);
 const { Post_Images, ...postAttributes } = post;
 ...

用户在使用 Sequelize 之前是否喜欢 post

Has the user liked the post before or not using Sequelize

node.js

sequelize.js