有没有办法通过单个查询更新插入列表？

发布于 2024-09-13 16:43:38 字数 1411 浏览 4 评论 0原文

我知道这个问题以前曾被问过，但那是不同的情况。我想要一个像这样的集合：

{
    "_id" : ObjectId("4c28f62cbf8544c60506f11d"),
    "pk": 1,
    "forums": [{
        "pk": 1,
        "thread_count": 10, 
        "post_count": 20,
    }, {
        "pk": 2,
        "thread_count": 5, 
        "post_count": 24,
    }]
}

我想要做的是更新插入“论坛”项目，增加计数器或添加项目（如果不存在）。

例如，要做这样的事情（我希望它有意义）：

db.mycollection.update({
    "pk": 3,
    "forums.pk": 2
}, {
    "$inc": {"forums.$.thread_count": 1},
    "$inc": {"forums.$.post_count": 1},
}, true)

并且有：

{
    "_id" : ObjectId("4c28f62cbf8544c60506f11d"),
    "pk": 1,
    "forums": [{
        "pk": 1,
        "thread_count": 10, 
        "post_count": 20,
    }, {
        "pk": 2,
        "thread_count": 5, 
        "post_count": 24,
    }]
},
{
    "_id" : ObjectId("4c28f62cbf8544c60506f11e"),
    "pk": 3,
    "forums": [{
        "pk": 2,
        "thread_count": 1, 
        "post_count": 1,
    }]
}

我肯定可以通过三个步骤完成：

用新项目更新整个集合
addToSet 将论坛项目添加到列表中
使用位置运算符增加论坛项目计数器

这就是说：

db.mycollection.update({pk:3}, {pk:3}, true)
db.mycollection.update({pk:3}, {$addToSet: {forums: {pk:2}}})
db.mycollection.update({pk:3, 'forums.pk': 2}, {$inc: {'forums.$.thread_counter': 1, {'forums.$.post_counter': 1}})

您知道更有效的方法吗？杰尔马诺·TIA

原文

I know this question has been asked before, but that's a different scenario.
I'd like to have a collection like this:

{
    "_id" : ObjectId("4c28f62cbf8544c60506f11d"),
    "pk": 1,
    "forums": [{
        "pk": 1,
        "thread_count": 10, 
        "post_count": 20,
    }, {
        "pk": 2,
        "thread_count": 5, 
        "post_count": 24,
    }]
}

What I want to do is to upsert a "forum" item, incrementing counters or adding an item if it does not exist.

For example to do something like this (I hope it makes sense):

db.mycollection.update({
    "pk": 3,
    "forums.pk": 2
}, {
    "$inc": {"forums.$.thread_count": 1},
    "$inc": {"forums.$.post_count": 1},
}, true)

and have:

{
    "_id" : ObjectId("4c28f62cbf8544c60506f11d"),
    "pk": 1,
    "forums": [{
        "pk": 1,
        "thread_count": 10, 
        "post_count": 20,
    }, {
        "pk": 2,
        "thread_count": 5, 
        "post_count": 24,
    }]
},
{
    "_id" : ObjectId("4c28f62cbf8544c60506f11e"),
    "pk": 3,
    "forums": [{
        "pk": 2,
        "thread_count": 1, 
        "post_count": 1,
    }]
}

I can surely make it in three steps:

Upsert the whole collection with a new item
addToSet the forum item to the list
increment forum item counters with positional operator

That's to say:

db.mycollection.update({pk:3}, {pk:3}, true)
db.mycollection.update({pk:3}, {$addToSet: {forums: {pk:2}}})
db.mycollection.update({pk:3, 'forums.pk': 2}, {$inc: {'forums.$.thread_counter': 1, {'forums.$.post_counter': 1}})

Are you aware of a more efficient way to do it?
TIA, Germano

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睫毛溺水了 2024-09-20 16:43:38

您可能已经发现，位置运算符不能在更新插入中使用：

位置运算符不能与 upsert 组合使用，因为它需要匹配的数组元素。如果您的更新导致插入，则“$”实际上将用作字段名称。

因此，您将无法在单个查询中获得所需的结果。

您必须将文档的创建与计数器更新分开。您自己的解决方案走在正确的轨道上。它可以被压缩为以下两个查询：

// optionally create the document, including the array
db.mycollection.update({pk:3}, {$addToSet: {forums: {pk:2}}}, true)

// update the counters in the array item
db.mycollection.update({pk:3, 'forums.pk': 2}, {$inc: {'forums.$.thread_counter': 1, 'forums.$.post_counter': 1}})

As you may have discovered, the positional operator cannot be used in upserts:

The positional operator cannot be combined with an upsert since it requires a matching array element. If your update results in an insert then the "$" will literally be used as the field name.

So you won't be able to achieve the desired result in a single query.

You have to separate the creation of the document from the counter update. Your own solution is on the right track. It can be condensed into the following two queries:

// optionally create the document, including the array
db.mycollection.update({pk:3}, {$addToSet: {forums: {pk:2}}}, true)

// update the counters in the array item
db.mycollection.update({pk:3, 'forums.pk': 2}, {$inc: {'forums.$.thread_counter': 1, 'forums.$.post_counter': 1}})

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