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[英]MONGODB update value inside object, inside array, inside collection
[英]mongodb: update array item inside of a post inside of a collection
我试图弄清楚如何更新属于帖子一部分的数组中的项目。 我确实找到了看起来最接近我想要的东西: MongoDB更新数组元素
但是我没有像这个例子所示的那样先排好特定的帖子。 但是我需要先使用_id查找特定的帖子,然后从结果帖子中更新数组中的一项。
我可以使用一个查询来执行此操作,还是需要先找到该项目然后再像另一个答案中的示例所示那样对其进行更新?
在下面的json中,我如何更新第一条评论:第一条评论?
编辑:
[{
"_id": "52c06c86b78a091f26000001",
"comments": [
{
"user_id": "52ad97bab142627664000001 ",
"username": "phacer",
"comment": "nice dress!!!",
"created": 1390668491909,
"_id": "_SvF-Ag4d6wFf9QR1KdAdFIpcCyI3cqm2F4rl3w7rdk="
},
{
"user_id": "52ad97bab142627664000001 ",
"username": "phacer",
"comment": "nice dress!!!",
"created": 1390668491909,
"_id": "_SvF-Ag4d6wFf9QR1KdAdFIpcCyI3cqm2F4rl3w7rdk="
}
],
"desc": "Something somethingson",
"hate": [],
"imageurl": "some url",
"love": [
{
"user_id": "52add4f4344e8ca867000001",
"username": "asd",
"created": 1390652212592
}
],
"tags": [
{
"y": 29.3,
"brand": "Zara",
"type": "Bow Tie",
"x": 20,
"color": "Black"
}
],
"user_id": "52add4f4344e8ca867000001"
},
{
"_id": "52c06c86b78a091f26000001",
"comments": [
{
"user_id": "52ad97bab142627664000001 ",
"username": "phacer",
"comment": "nice dress!!!",
"created": 1390668491909,
"_id": "_SvF-Ag4d6wFf9QR1KdAdFIpcCyI3cqm2F4rl3w7rdk="
}
],
"desc": "Something somethingson",
"hate": [],
"imageurl": "some url",
"love": [
{
"user_id": "52add4f4344e8ca867000001",
"username": "asd",
"created": 1390652212592
}
],
"tags": [
{
"y": 29.3,
"brand": "Zara",
"type": "Bow Tie",
"x": 20,
"color": "Black"
}
],
"user_id": "52add4f4344e8ca867000001"
}]
您应该考虑使用$elemMatch
( 文档 ),如下所示:
.update({'_id': '52c06c86b78a091f26000001', 'comments' : {$elemMatch: {'_id': '_SvF-Ag4d6wFf9QR1KdAdFIpcCyI3cqm2F4rl3w7rdk='}}}, {$set : {'comments.$.comment': 'Lame dress!'}})
您可以在Mongo中使用位置运算符来访问特定的数组元素,如下所示
db.collection.update( { _id: 52c06c86b78a091f26000001 }, { $set: { "comments.$1.comment" : "dress" } } )
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