如何在MongoDB中$ set子子数组项 [英] How to $set sub-sub-array items in MongoDB

问题描述

我正在开发一个Web应用程序，它具有一个类似于门户的组件(想像多个面板，可以在各个列之间进行药物处理，并进行添加或删除).我正在使用MongoDB以类似这样的格式存储此信息...

I'm developing a webapp which has a portal-ish component to it (think like multiple panels that can be drug around from column to column and added or removed). I'm using MongoDB to store this info with a format like so...

{
    _id: ObjectId(...),
    title: 'My Layout',
    columns: [
        {
            order: 1,
            width: 30,
            panels: [
                { title: 'Panel Title', top: 100, content: '...' },
                { title: 'Panel Title', top: 250, content: '...' },
            ]
        },
        {
            ... multiple columns ...
        }
    ]
}

我正在尝试对 update()使用原子/修饰符操作，这令人困惑.如果我只想更新特定面板的一个属性，该如何引用?

I'm attempting to use atomic/modifier operations with update() and this is getting confusing. If I wanted to just update one property of a specific panel, how do I reference that?

update(
    { _id: ObjectId(...) },
    { $set: { columns.[???].panels.[???].top: 500 }
)

推荐答案

如果您知道数组中的索引，则可以使用点符号直接访问数组元素.

If you know the index in the array you can access the array element directly using dot notation.

update(
{ _id: ObjectId(xxxx) },
{ $set: { 'columns.0.panels.0.top' : 125}}
)

确保将引号中的点号路径括在字符串中.

Make sure you encase the dot notated path in quotes as a string.

要提供有关如何动态运行的更多详细信息，我将在PHP中给出一个示例:

To give more detail on how this could work dynamically, I'll give an example in PHP:

$action = array("columns.$colNum.panels.$panelNum" => $newValue);

是的，有位置运算符，但是似乎不够高级来更改数组在数组中，这在MongoDB 1.7.0中可能会更改

Yes there is the positional operator, but it does not appear to be advanced enough to change arrays within arrays, this may change in MongoDB 1.7.0

您可以执行另一种方法，而不是尝试将这些信息填充到嵌套文档中.尝试将其弄平.您可以创建一个包含面板&列对象:

There is an alternative you can do instead of trying to stuff this information into a nested document. Try to flatten it out. You can create a collection that has panel & column objects:

列对象:

{
_id: // MongoId
type: 'column',
user: 'username',
order: 1,
width: 30,
}

面板对象:

{
_id: //MongoId
type: 'panel',
user: 'username',
parentColumn: //the columns _id string
top: 125,
left: 100
}

然后您可以通过执行以下操作找到属于用户的所有列:

Then you can find all columns that belong to a user by doing:

find({ type: 'column', user:'username'});

您可以通过执行以下操作找到特定列的所有面板:

You can find all panels for a specific column by doing:

find({type: 'panel', columnOwner:'ownerID'});

由于每个列和面板都有MongoDB为其赋予的唯一ID，因此您可以轻松查询和自动设置选项.

Since each column and panel will have a unique ID given by MongoDB to it, you can easily query and atomically set options.

update({'_id': ObjectId('idstring')}, {$set : { 'top' : 125}});

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