MongoDB: How do I update a single subelement in an array, referenced by the index within the array?

I'm trying to update a single subelement contained within an array in a mongodb document. I want to reference the field using its array index (elements within the array don't have any fields that I can guarantee will be unique identifiers). Seems like this should be easy to do, but I can't figure out the syntax.

Here's what I want to do in pseudo-json.

Before:

{
_id : ...,
other_stuff ... ,
my_array : [
{ ... old content A ... },
{ ... old content B ... },
{ ... old content C ... }
]
}

After:

{
_id : ...,
other_stuff ... ,
my_array : [
{ ... old content A ... },
{ ... NEW content B ... },
{ ... old content C ... }
]
}

Seems like the query should be something like this:

//pseudocode
db.my_collection.update(
{_id: ObjectId(document_id), my_array.1 : 1 },
{my_array.$.content: NEW content B }
)

But this doesn't work. I've spent way too long searching the mongodb docs, and trying different variations on this syntax (e.g. using $slice, etc.). I can't find any clear explanation of how to accomplish this kind of update in MongoDB.

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最佳答案

As expected, the query is easy once you know how. Here's the syntax, in python:

db["my_collection"].update(
{ "_id": ObjectId(document_id) },
{ "$set": { 'documents.'+str(doc_index)+'.content' : new_content_B}}
)
小开

在 mongo 样式中，使用“ $”位置运算符。 查看此 链接了解详细信息。

db.my_collection.update(
{_id: ObjectId(document_id), my_array.1 : 1 },
{ $set: { "my_array.$.content" : "NEW content B" } }
)
小开

Update of an array element referenced by an index (e.g. 1 ) in Mongo Shell can also be done by directly indicating the index value:

db.my_collection.update(
{_id : "document_id"},
{$set : {"my_array.1.content" : "New content B"}}
)
小开 
db.my_collection.update(
{_id: ObjectId(document_id), my_array : { ... old content A ... } },
{ $set: { "my_array.$.content" : "NEW content B" } }
)
小开

如果 旧内容 B的键为“ value”，那么可以使用 mongoDB 的 updateOne 函数传递数组中元素的索引:

[
...
"value" : "old content A"
"value" : "old content B"
"value" : "old content C"
...
]

the command should be like this:

db.collection.updateOne({"_id" : "...,"},{$set: {"my_array.1.value": "NEW content B"}})
小开

在 Javascript 中，一个简单的方法是:

 const index = 1;


...  {   $set: { [`myArray.${index}.value`]: "new content"}  },  ...
小开

When it's required to update an array element without knowing it's actual index but having a 元素的唯一标识符:

// Modify a comment in a bucket
db.POST_COMMENT.update(
{
"_id": ObjectId("5ec424a1ed1af85a50855964"),
"bucket.commentId": "5eaf258bb80a1f03cd97a3ad_lepf4f"
},
{
$set: {
"bucket.$.text": "Comment text changed",
"bucket.$.createdDate": ISODate("2015-12-11T14:12:00.000+0000")
}
}
)

这里的 abc0是一个数组元素的唯一标识符。

小开

当需要更新一个数组元素时，不知道它是一个实际的索引，但是有一个元素的唯一标识符

db.getCollection('profiles').update(
{
'userId':'4360a380-1540-45d9-b902-200f2d346263',
'skills.name':'css'
},
{
$set: {'skills.$.proficiencyLevel': 5}
},
{
multi: true
}
)
小开

If you want to update the authorName of the testimonial having _id = 60c4918d74c30165ba585c14 from the following document:

"business": {
"ownerId": "60a5ebad7432d91b853c0277",
"testimonials": [
{
"_id": "60c4912877dd5664f2201b08",
"authorName": "user1",
"authorBio": "User from 10 years",
"image": "user1/img1",
"review": "asdfiuahsdfpoiuashdpfoaspdlfkjn;alsfpuoh"
},
{
"_id": "60c4918d74c30165ba585c14",
"authorName": "user2",
"authorBio": "User from 3 years",
"image": "user/img1",
"review": "asdpfuahsfljnsadfoihsf."
}
],
"createdAt": "2021-06-11T20:12:56.666Z",
"updatedAt": "2021-06-12T11:11:56.696Z",
    

}

那么下面这个猫鼬式的问题就奏效了:

await BusinessModel.updateOne(
{
'_id': Mongoose.Types.ObjectId(businessId),
'testimonials._id': Mongoose.Types.ObjectId('60c4918d74c30165ba585c14')
},
{
$set: { 'testimonials.$.authorName' : 'new author name' }
}
);

请参阅 https://docs.mongodb.com/drivers/node/fundamentals/crud/write-operations/embedded-arrays/

小开

如果您有一个包含简单字符串的“普通”数组，那么这个方法就奏效了:

db.paintings.insertMany([
{_id: 1, colors: ["red", "blue", "green"]},
{_id: 2, colors: ["red", "yellow"]}


db.paintings.updateMany(
{colors: "red"},
{$set: {"colors.$": "magenta"}})

位置 $运算符充当与查询文档匹配的第一个元素的占位符 来源


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