如何使用JS将空数组保存到mongodb中 [英] How can I save an empty array into mongodb using js

问题描述

基本上，我的应用程序正在运行，但我遇到了一个问题：如果我传递的对象包含要保存的空数组，则该数组不会保存到数据库中。我不确定这是js还是mongo驱动程序中的问题，但是为了保存空数组，我需要像这样传递数组： products：[''] 。

Basically I got my app up an running but I'm stuck with a problem: if I pass an object that contains an empty array to be saved, the array is not saved into the db. I'm not sure this is a problem in js or the mongo driver, but in order to save the empty array I need to pass the array like so: products: [''].

这是我的mongo文档的结构：

This is the structure of my mongo document:

_id: ObjectId(...),
name: 'String',
subcategories: [
    {
        subcategory: 'string',
        products: [
            {
                 name: 'string'
                 price: integer
            }
        ]
    }
]

因此在我的前端，我通过ajax调用抓取整个文档，将一个新对象推入子类别数组。新对象看起来像这样：

So in my front-end I'm grabbing the whole document through an ajax call pushing a new object into the subcategories array. The new object looks like this:

{子类别：'字符串'，产品：['']}

这行之有效，直到我需要在数组中插入一个新对象：因为我已经抓住了整个对象，所以将新对象推到了数组中，前一个看起来像这样：

And this works okay until I need to insert a new object inside the array: Because I've grabbed the whole object, pushed the new object to the array, the previous one looks like this:

{子类别：'string'}

在此过程中没有提及 products：[] 数组。

Having lost the mention to products:[] array in the process.

我如何获得围绕这个？我需要在我的对象中有一个空数组。

How can I get around this? I need to be able to have empty arrays in my object.

编辑

我在前端执行的操作：使用 $。get 获得了整个对象，该对象返回：

What I did on front end: Got the whole object with $.get which returned:

var obj = 
_id: ObjectId(...),
name: 'String',
subcategories: [
    {
        subcategory: 'Subcategory1',
        products: [
            {
                 name: 'string'
                 price: integer
            }
        ]
    }
];

然后在前端，我将新对象类别推送到子类别数组中：

Then on the front end I've pushed the new object category inside the subcategories array:

data.subcategories.push({subcategory: 'Subcategory2', products: ['']})

其中subcat是具有类别名称的字符串。在我的数据库上，我可以看到已经成功添加了对象：

Where subcat was a string with the category name. On my db I could see that I've successfully added the object:

var obj = 
_id: ObjectId(...),
name: 'String',
subcategories: [
    {
        subcategory: 'Subcategory1',
        products: [
            {
                 name: 'string'
                 price: integer
            }
        ]
    },
    {
         subcategory: 'Subcategory2'
         products: []
    }
];

问题是当我想添加另一个子类别时，前一个返回空：

The problem was when I wanted to add another subcategory, the previous one return empty:

var obj = 
_id: ObjectId(...),
name: 'String',
subcategories: [
    {
        subcategory: 'Subcategory1',
        products: [
            {
                 name: 'string'
                 price: integer
            }
        ]
    },
    {
         subcategory: 'Subcategory2'
    },
    {
         subcategory: 'Subcategory3'
         products: []
    },
];

因为在某个时候，空数组已从对象中删除。就像我说的，我确实在前端修复了此错误，因此解决了玉石抛出的错误，但是我仍然发现 products：[] 已被删除很奇怪

Because at some point the empty array was removed from the object. Like I said, I did fix this in the front end, so the error jade was throwing has been addressed, but I still find odd that the products: [] was being removed from the document.

我是MongoDb和node的新手，更不用说我也是JS的新手，所以它很可能是我的一项功能

I'm new to MongoDb and node, not to mention that I'm also new with JS, so it might well be a feature that I'm unaware of.

推荐答案

将空数组传递给Mongo时，它们被解释为空文档{}。 Zend Json编码器会将它们解释为空数组[]。我了解无法确定哪一个是正确的。
如果数组为空，请尝试以

When passing empty arrays to Mongo they are interpreted as empty documents, {}. Zend Json encoder will interpret them as empty arrays []. I understand that it's not possible to tell which one is correct. Incase of empty arrays try posting as

Array [null];
而不是Array [];

这会很好

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