sequelize.js - Sequelize 子类型示例

Question

我正在尝试使用简单的 CRUD 操作复制示例 here。我在这个例子中访问共享外键并设置它有困难。关于如何访问评论对象的“可评论”字段的任何建议？由于 {constraint: false} (未生成外键约束)，它没有意义。

Answer 1

这是工作示例:

var Sequelize = require('sequelize');
var sequelize = new Sequelize(
  'my_test', // db name
  'postgres', // username
  'postgres', // password
  {
    host: 'localhost',
    dialect: 'postgres',
    port:5432,
    dialectOptions: {
        ssl: false
    },
    logging: true, //verbose
    pool: {
      max: 5,
      min: 0,
      idle: 10000
    }
  }
);


// define models

var Image = sequelize.define('image', {
  title: Sequelize.STRING
});

var Post = sequelize.define('post', {
  title: Sequelize.STRING
});

var Comment = sequelize.define('comment', {
  title: Sequelize.STRING,
  commentable: Sequelize.STRING,
  commentable_id: Sequelize.INTEGER
}
, {
  instanceMethods: {
    getItem: function() {
      console.log(this);
      console.log('====================');
      console.log('====================');
      //console.log(this.getTitle());

      //console.log(this.getCommentable());
      console.log('====================');

      return this['get' + this.commentable.substr(0, 1).toUpperCase() + this.commentable.substr(1)](); 
      //where is the definition of this method? getImage/getPost.
    }
  }
}
);


// relations
// post-comment
Post.hasMany(Comment, {  //adds fk in Comment
  foreignKey: 'commentable_id',
  constraints: false,
  scope: {
    commentable: 'post'
  }
});

Comment.belongsTo(Post, {   // fk on the src (Comment)
  foreignKey: 'commentable_id',
  constraints: false,
   as: 'post'
});

// Image-comment
Image.hasMany(Comment, {      //adds fk in Comment
  foreignKey: 'commentable_id',
  //as:'commentableId',
  constraints: false,
  scope: {
    commentable: 'image'
  }
});
Comment.belongsTo(Image, {    // fk on the src (Comment)
  foreignKey: 'commentable_id',
  constraints: false,
  as: 'image'
});

//=========

sequelize.sync()
  .then(function () {
    console.log('---------- sync');
    var image1 = Image.build({title: 'very_important_task.jpg'});
    var image1Promise = image1.save()
                              .then(function(i){

                                var commentPromise=i.createComment({ //create comment through image sets commentable and commentable_id
                                  title: 'my comment 999999999'
                                });

                                // break the previous promise to be abel to access to image1 when we keep on adding to the chain
                                commentPromise
                                  .then(function(c){  // now comment is saved.
                                    console.log('##################### All comments: ');
                                    image1.getComments()
                                          .then(function(results){    //results[0] is the first result
                                            console.log( 
                                              results.map(
                                                function(item) {
                                                  return item['title']; //Or image.title         item.commentable_id  === image id
                                                }
                                              )
                                            );
                                          });


                                    // after comment creation check accessing to comentable reference of this comment
                                    c.getItem()
                                     .then(function(i){
                                        console.log(i.title)
                                      });
                                });


      //creat lots of comments

      Comment.bulkCreate([ 
        {title: 'my comment 1', commentable_id:image1.id, commentable:'image'}, 
        {title: 'my comment 2', commentable_id:image1.id, commentable:'image'}
      ]).then(function() {
          image1.getComments()
                .then(function(results){
                  console.log(
                    results.map(
                      function(item) {
                        return item['title'];
                      }
                    )
                  );
                });
         });

    }); //save promise of image to make sure it is created for any code accessing it
  });