英文:
Update a field in an array only if it exists via mongo query
问题
我正在尝试更新数组中的字段，但使用 $set 会在字段不存在时添加该字段，如何避免这种情况？
以下是您的模型：
[
{
"config": {
"isEnabled": false,
"test": {
"sub": [
{
"sub": [
{},
{},
{},
{},
{
"k": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"k": "l"
}
]
},
{
"sub": [
{},
{},
{},
{}
]
}
]
}
}
}
]
这是我运行的查询：
db.collection.update({
"config.isEnabled": false
},
{
"$set": {
"config.test.sub.$[].sub.4": {
"b": "l"
}
}
})
输出结果：
[
{
"_id": ObjectId("5a934e000102030405000000"),
"config": {
"isEnabled": false,
"test": {
"sub": [
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
}
]
}
}
}
]
但我想要达到这个结果：
[
{
"_id": ObjectId("5a934e000102030405000000"),
"config": {
"isEnabled": false,
"test": {
"sub": [
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{}
]
}
]
}
}
}
]
如果您观察模型数组中第三个元素中的最后一个元素，它不包含 k=l，因此我不想在数组的最后一个元素中设置该字段。
也就是说，在模型中，这是元素：
{
"sub": [
{},
{},
{},
{}
]
}
当我运行我的查询时，它会更新该元素为：
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
}
但我不希望它更新该元素。
您可以在Mongo Playground中找到此示例的链接：Mongo Playground For The Above Example
如果您想通过Mongoose实现此操作，也是可行的。
谢谢您的时间，我感激任何帮助。我尝试使用 addToSet 和 setOnInsert，但都不起作用，我知道可以找到文档，然后手动添加一些逻辑来适当地更新字段，然后更新文档，但我想知道是否有一种通过Mongo查询实现的方法。
英文:
I'm trying to update a field in an array, but using $set adds that field if it doesn't already exist, how to avoid that?
This is my model:
[
{
"config": {
"isEnabled": false,
"test": {
"sub": [
{
"sub": [
{},
{},
{},
{},
{
"k": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"k": "l"
}
]
},
{
"sub": [
{},
{},
{},
{}
]
}
]
}
}
},
]
Here's the query I'm running
db.collection.update({
"config.isEnabled": false
},
{
"$set": {
"config.test.sub.$[].sub.4": {
"b": "l"
}
}
})
Output:
[
{
"_id": ObjectId("5a934e000102030405000000"),
"config": {
"isEnabled": false,
"test": {
"sub": [
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
}
]
}
}
}
]
But I want to attain this result:
[
{
"_id": ObjectId("5a934e000102030405000000"),
"config": {
"isEnabled": false,
"test": {
"sub": [
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
},
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
}
]
}
}
}
]
If you observe the last element in the third element in the array of the model, it does not contain k=l, hence I do not want to set that field in the last element of the array
i.e, in the model this is the element:
{
"sub": [
{},
{},
{},
{}
]
}
When I run my query it updatea that element to:
{
"sub": [
{},
{},
{},
{},
{
"b": "l"
}
]
}
But I don't want it to update that element
Link to mongo playground:
Mongo Playground For The Above Example
> IF THIS CAN BE ACHIEVED IN MONGOOSE, THAT'D WORK TOO
Thanks for your time and I appriciate any help
I tried using addToSet and setOnInsert, none of those work, I know I can find the documents then manually add some logic to update the fields appropriately then update the document but I want to know if there's a way to achieve it via mongo query
答案1
得分: 0
一种选项是使用 $[<identifier>] 进行此操作：
db.collection.update(
{"config.isEnabled": false},
{$set: {"config.test.sub.$[item].sub.4": {"b": "l"}}},
{arrayFilters: [{"item.sub.4": {$exists: true}}]}
)
在playground示例上查看它的工作方式。
英文:
One option is to use $[<identifier>] for this:
db.collection.update(
{"config.isEnabled": false},
{$set: {"config.test.sub.$[item].sub.4": {"b": "l"}}},
{arrayFilters: [{"item.sub.4": {$exists: true}}]}
)
See how it works on the playground example
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