具有TypeError的mongooseJS:无法读取未定义的属性“构造函数"

问题描述

我正在尝试通过从文件中读取数据并使用'update'方法来更新数据库中的数据.

I'm trying to update data in a database by reading data from a file and using the 'update' method.

var Model = require('./dbIndex').Model

BioMetrics.update({AID: AID}, 
  {$pushAll: {
  attr1: data[5] === '' ? undefined : {val: data[5], dt: date},
  attr2: data[6] === '' ? undefined : {val: data[6], dt: date},
  attr3: data[10] === '' ? undefined : {val: data[10], dt: date}
 }}, options, callback);

运行此命令时，出现以下错误:
TypeError: Cannot read property 'constructor' of undefined

When I run this I get the following error:
TypeError: Cannot read property 'constructor' of undefined

Mongo不知道undefined是什么意思?我的印象是，当undefined为true时，Mongo只会忽略该属性.

Mongo does not know what undefined means? I had the impression that when undefined is true Mongo just ignores that attribute.

有人可以解释这里发生了什么吗?

Can someone explain what's happening here?

推荐答案

MongoDB可能会忽略设置为undefined的字段，但是Mongoose却没有，因为它具有可使用的架构，并将尝试将值转换为正确的类型按照架构中的定义.

MongoDB may ignore fields set to undefined, but Mongoose doesn't as it has a schema to work from and will try and cast values to the right types as defined in the schema.

在这种情况下，您可以通过编程方式建立$pushAll值，使其仅包含所需的属性:

For a case like this you can build up your $pushAll value programmatically to only include the attributes you want:

var value = {};
if (data[5] !== '') {
    value.attr1 = {val: data[5], dt: date};
}
if (data[6] !== '') {
    value.attr2 = {val: data[6], dt: date};
}
if (data[10] !== '') {
    value.attr3 = {val: data[10], dt: date};
}
BioMetrics.update({AID: AID}, {$pushAll: value}, options, callback);

这篇关于具有TypeError的mongooseJS:无法读取未定义的属性“构造函数"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！