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Sequelize官网翻译十 —— Paranoid

 4 years ago
source link: https://zhuanlan.zhihu.com/p/125027110
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Sequelize官网翻译十 —— Paranoid

Sequelize也支持paranoid表。paranoid表是在被告之要删除记录时并不会真正的物理上删除，而是添加一个存有删除请求时间戳deletedAt的特殊字段。

paranoid表就是软删除而非硬删除机制的表。

把模型定义为paranoid

传递paranoid: true参数给模型定义中。paranoid要求必须启用时间戳，即必须传timestamps: true。

也能把默认的deletedAt的名字给换掉。

 class Post extends Model {}
 Post.init({ /* attributes here */ }, {
   sequelize,
   paranoid: true,
 ​
   // If you want to give a custom name to the deletedAt column
   deletedAt: 'destroyTime'
 });

删除

当调用destroy方法的时候，就会发生软删除

 await Post.destroy({
   where: {
     id: 1
   }
 });
 // UPDATE "posts" SET "deletedAt"=[timestamp] WHERE "deletedAt" IS NULL AND "id" = 1

如果此时还想是硬删除，你可以使用force: true参数

 await Post.destroy({
   where: {
     id: 1
   },
   force: true
 });
 // DELETE FROM "posts" WHERE "id" = 1

上面的例子用了静态的destroy方法，但对于实例方法也是相同的

 const post = await Post.create({ title: 'test' });
 console.log(post instanceof Post); // true
 await post.destroy(); // Would just set the `deletedAt` flag
 await post.destroy({ force: true }); // Would really delete the record

恢复

想要恢复软删除的记录，可以调用restore方法，它也同时存在有静态和实例方法两种形式。

 // Example showing the instance `restore` method
 // We create a post, soft-delete it and then restore it back
 const post = await Post.create({ title: 'test' });
 console.log(post instanceof Post); // true
 await post.destroy();
 console.log('soft-deleted!');
 await post.restore();
 console.log('restored!');
 ​
 // Example showing the static `restore` method.
 // Restoring every soft-deleted post with more than 100 likes
 await Post.restore({
   where: {
     likes: {
       [Op.gt]: 100
     }
   }
 });

查询的行为

Sequelize执行的查询都会忽略软删除掉的记录(但原生查询不会)。

这意味着，findAll方法不会看到软删除掉的记录，只会拿到那些没有软删除的记录。

即便你调用findByPk用主键来查询软删除掉的记录，也将返回null。

如果仍想把软删除掉的记录查询出来，可以传递paranoid: false参数给查询方法，比如

 await Post.findByPk(123); // This will return `null` if the record of id 123 is soft-deleted
 await Post.findByPk(123, { paranoid: false }); // This will retrieve the record
 ​
 await Post.findAll({
   where: { foo: 'bar' }
 }); // This will not retrieve soft-deleted records
 ​
 await Post.findAll({
   where: { foo: 'bar' },
   paranoid: false
 }); // This will also retrieve soft-deleted records

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