Sequelize 模型引用 vs 关联 [英] Sequelize model references vs associations

问题描述

刚开始使用 Sequelize 并且我已经设置了一堆模型和种子，但我无法弄清楚引用与关联.如果他们甚至按照我认为的那样做，我就看不到引用的用例，但我在文档中找不到很好的解释.

Just starting to use Sequelize and I've setup a bunch of models and seeds, but I can't figure out references vs associations. I don't see the use case for references if they even do what I think they do, but I couldn't find a good explanation in the docs.

引用和关联是多余的吗?

Is this redundant having references and associations?

module.exports = (sequelize, DataTypes) => {
  const UserTask = sequelize.define('UserTask',
    {
      id: {
        primaryKey: true,
        type: DataTypes.UUID,
        defaultValue: DataTypes.UUIDV4
      },
      userId: {
        type: DataTypes.UUID,
        references: { // <--- is this redundant to associate
          model: 'User',
          key: 'id'
        }
      }
      // ... removed for brevity
    },
    {
      classMethods: {
        associate: models => { <--- makes references redundant?
          UserTask.belongsTo(models.User, {
            onDelete: 'CASCADE',
            foreignKey: {
              fieldName: 'userId',
              allowNull: true,
              require: true
            },
            targetKey: 'id'
          });
        }
      }
    }
  );
  return UserTask;
};

推荐答案

使用 references 可以创建对另一个表的引用，而无需添加任何约束或关联.这意味着这只是一种通知数据库该表引用另一个表的方式.

Using references you create a reference to another table, without adding any constraints, or associations. Which means that is just a way of signaling the database that this table has a reference to another.

创建一个 association 将向属性添加外键约束.您可以执行关联功能背后的所有魔法.即 User.getTasks();

Creating an association will add a foreign key constraint to the attributes. And the you can perform all the magic behind it the association functions. i.e User.getTasks();

有关 references 的更多信息，请访问:https://sequelize.readthedocs.io/en/latest/docs/associations/#foreign-keys_1

More info about references here: https://sequelize.readthedocs.io/en/latest/docs/associations/#foreign-keys_1

关于 association 在这里:http://docs.sequelizejs.com/manual/tutorial/associations.html

这篇关于Sequelize 模型引用 vs 关联的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！