node.js - Sequelize 关联不起作用

Question

我有两个模型发布和评论。一个帖子可以有很多评论，一个评论可以属于一个帖子。这是使用 sequelize 生成的类。

发布

'use strict';
module.exports = function(sequelize, DataTypes) {
  var post = sequelize.define('post', {
    title: DataTypes.STRING
  }, {
    classMethods: {
      associate: function(models) {
        post.hasMany(models.comment)
      }
    }
  });
  return post;
};

评论

'use strict';
module.exports = function(sequelize, DataTypes) {
  var comment = sequelize.define('comment', {
    title: DataTypes.STRING,
    body: DataTypes.STRING,
    postId: DataTypes.INTEGER
  }, {
    classMethods: {
      associate: function(models) {
        comment.belongsTo(models.post)
      }
    }
  });
  return comment;
};

这是注释迁移文件:

'use strict';
module.exports = {
  up: function(queryInterface, Sequelize) {
    return queryInterface.createTable('comments', {
      id: {
        allowNull: false,
        autoIncrement: true,
        primaryKey: true,
        type: Sequelize.INTEGER
      },
      title: {
        type: Sequelize.STRING
      },
      body: {
        type: Sequelize.STRING
      },
      postId: {
        type: Sequelize.INTEGER,
        allowNull: false,
        references: {
          model: "posts",
          key:"id"
        }

      },
      createdAt: {
        allowNull: false,
        type: Sequelize.DATE
      },
      updatedAt: {
        allowNull: false,
        type: Sequelize.DATE
      }
    });
  },
  down: function(queryInterface, Sequelize) {
    return queryInterface.dropTable('comments');
  }
};

我没有从帖子到评论的关系。

之后，我创建了一个帖子，然后创建了一个评论。后来我检索评论并指示在我收到错误时获取与评论相关的帖子:

Unhandled rejection SequelizeEagerLoadingError: post is not associated to comment!

这是我使用的代码:

// create a post object
/*
const post = models.post.build({
    title: "Hello World"
})

// save a new post
post.save().then(function(newPost){
  console.log(newPost)
})
*/

// create a comment
/*
const comment = models.comment.build({
   title: "Comment",
   body: "Body",
   postId : 1
})

comment.save().then(function(newComment){
  console.log(newComment)
}) */

// get the comment and also the post it belongs to
models.comment.findOne({
  include: [
    {
      model: models.post 
    }
  ]
}).then(function(comment){
    console.log(comment)
})

Answer 1

首先需要处理拒绝，防止出现未处理的拒绝错误:

models.comment.findOne({
  include: [
    {
      model: models.post
    }
  ]
}).then(function (comment) {
  console.log(comment)
}).catch(function (error) {
  console.log(error);
});

以及关于错误描述 "post is not associated to comment" 。看起来你放错了实例。也许你需要发表评论而不是整篇文章:

include: [
  {
    model: models.post.comment
  }
]