猫鼬JobSchema。pre('update'， function(n){n()})抛出:TypeError:不能读取未定义的属性'numAsyncPres'。

I have this Schema in mongoose and when I use the pre with update, I get this error.

我在mongoose中有这个模式，当我使用pre和update时，我就会得到这个错误。

JobSchema.pre('update', function(n){n()})

Full error

完整的错误

C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\utils.js:413
        throw err;
              ^
TypeError: Cannot read property 'numAsyncPres' of undefined
    at Model._lazySetupHooks (C:\web\production01_server\node_modules\production\node_modules\mongoose\node_modules\hooks\hooks.js:149:49)
    at Model.pre (C:\web\production01_server\node_modules\production\node_modules\mongoose\node_modules\hooks\hooks.js:113:10)
    at Model.doQueue (C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\document.js:1116:41)
    at Model.Document (C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\document.js:55:8)
    at Model.Model (C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\model.js:26:12)
    at Model.model (C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\model.js:910:11)
    at new Model (C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\connection.js:418:15)
    at cb (C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\query.js:804:16)
    at C:\web\production01_server\node_modules\production\node_modules\mongoose\lib\utils.js:408:16
    at C:\web\production01_server\node_modules\production\node_modules\mongoose\node_modules\mongodb\lib\mongodb\cursor.js:133:9

Notes:

注:

pre('save' WORKS
(“保存”
post('update' Doesn't throw error and doesn't works
post('update'不会抛出错误，也不会起作用)。

4 个解决方案

#1

Mongoose 4.0 supports pre update hooks via Query middleware. http://mongoosejs.com/docs/middleware.html

Mongoose 4.0通过查询中间件支持预更新钩子。http://mongoosejs.com/docs/middleware.html

schema.pre('update', function() {
  console.log(this instanceof mongoose.Query); // true
  this.start = Date.now();
});

schema.post('update', function() {
  console.log(this instanceof mongoose.Query); // true
  console.log('update() took ' + (Date.now() - this.start) + ' millis');
});

A note of caution:

值得注意的是:

"Query middleware differs from document middleware in a subtle but important way: in document middleware, this refers to the document being updated. In query middleware, mongoose doesn't necessarily have a reference to the document being updated, so this refers to the query object rather than the document being updated."

“查询中间件与文档中间件的区别非常细微但很重要:在文档中间件中，这是指正在更新的文档。在查询中间件中，mongoose并不一定要对正在更新的文档有引用，所以这指的是查询对象，而不是正在更新的文档。

#2

According to the Mongoose documentation, the pre and post middleware functions support:

根据Mongoose文档，pre和post中间件功能支持:

init
初始化
validate
验证
save
保存
remove
删除

No support for update.

不支持更新。

#3

It's true that Mongoose doesn't support hooks on Model APIs other than those Greg listed above. However, an update hook can be done via Monkey-patch. The Hooker NPM package is a good way of doing this cleanly.

确实，Mongoose不支持其他模型api上的钩子。但是，更新钩子可以通过Monkey-patch完成。Hooker NPM软件包是一个很好的方法。

The RESTeasy project which is a Boilerplate for Node REST APIs has code that demonstrates how to do it:

RESTeasy项目是节点REST api的样板，它的代码演示了如何做:

var hooker = require('hooker');

var BaseSchema = new mongoose.Schema({
  sampleString: {
    type: String
  }
});

var BaseModel = mongoose.model('Base', BaseSchema);

// Utilize hooks for update operations. We do it in this way because MongooseJS
// does not natively support update hooks at the Schema level. This is a way
// to support it.
hooker.hook (BaseModel, 'update', {
  pre: function () {
    // Insert any logic you want before updating to occur here
    console.log('BaseModel pre update');
  },
  post: function () {
    // Insert any logic you want after updating to occur here
    console.log('BaseModel post update');
  }
});

// Export the Mongoose model
module.exports = BaseModel;

#4

I found this: https://github.com/LearnBoost/mongoose/issues/538 So no pre for update...

我发现了这个:https://github.com/learnboost/mongoose/es/538，所以没有更新的pre…

#1