Sequelize 'hasMany' 关联（模型）计数在查询执行中的属性

Question

续集版本：4.22.6， MySql版本：5.7.8 我想在查询执行中将 'hasMany' 关联（CompanyUser）计数（在 _user_count_ 的位置）

/**
* Company user associate with Company with belongsTo relation
*/
`CompanyUser.belongsTo(Company, { foreignKey: 'company_id', targetKey: 'id'});`

/**
* Company  associate with Company user with hasMany relation
*/
`Company.hasMany(CompanyUser, { foreignKey: 'company_id', sourceKey: 'id'});`

`return Company.findAll({
    attributes: [
        'id', 'title', 'is_enabled', '_user_count_'
    ]
    include: [
        {
            model: sqConn.CompanyUser,
            attributes: ['id'],
        },
        {
            model: sqConn.CompanyLogo,
            attributes:['file_object'],
        }
    ],
}).then(function(model) {
    return sequelize.Promise.resolve(model);
}).catch(function(err) {
    return sequelize.Promise.reject(err);
});`

带有左连接的简单 MySQL 查询可以正常工作并给出计数。

Answer 1

这对我有用：

await PostModel.findAll({
  group: ['posts.id'],
  order: [['createdAt', 'DESC']],
  include: [
    {
      model: CategoryModel,
      attributes: ['title'],
      where: { title: categoryTitle }
    },
    { model: CommentModel },
    { model: UserModel, attributes: ['fullname', 'id'] }
  ],
  attributes: [
    'title', 'content', 'description', 'thumbnail', 'baner', 'createdAt', 'updatedAt',
    [Sequelize.fn('COUNT', 'comment.id'), 'commentsCounter']
  ]
});

协会：

• 发布 M:N 类别
• 发表 1:N 评论
• 发布 N:1 用户

请注意这部分是'comment.id' 而不是'comments.id'。

如果您使用'comments.id'，它会为您抛出此错误：SequelizeDatabaseError: missing FROM-clause entry for table "comments"

我的模型 - 更新： 和评论

const { sequelize } = require('./index');
const { Model, DataTypes } = require('sequelize');
class CommentModel extends Model {};
CommentModel.init({
    id: {
        primaryKey: true,
        type: DataTypes.UUID,
        defaultValue: DataTypes.UUIDV4
    },
    content: {
        type: DataTypes.TEXT,
        allowNull: false
    }
}, {
    sequelize,
    modelName: 'comments',
    timestamps: true,
    paranoid: false
});

module.exports = CommentModel;

Answer 2

您可以使用sequelize.fn，尝试运行以下查询：

Company.findAll({
    attributes: [
        'id', 'title', 'is_enabled',
        [sequelize.fn('count', sequelize.col('company_users.id')) ,'user_count'] // <---- Here you will get the total count of user
    ],
    include: [
        {
            model: sqConn.CompanyUser,
            attributes: [] // <----- Make sure , this should be empty
        }
    ],
    group: ['companies.id'] // <---- You might require this one also
}).then(data => { 
    console.log(data); // <---- Check the output
})