Essentially I'm trying to filter OUT subdocuments and sub-subdocuments that have been "trashed". Here's a stripped-down version of my schema:
permitSchema = {
_id,
name,
...
feeClassifications: [
new Schema({
_id,
_trashed,
name,
fees: [
new Schema({
_id,
_trashed,
name,
amount
})
]
})
],
...
}
So I'm able to get the effect I want with feeClassifications
. But I'm struggling to find a way to have the same effect for feeClassifications.fees
as well.
So, this works as desired:
Permit.aggregate([
{ $match: { _id: mongoose.Types.ObjectId(req.params.id) }},
{ $project: {
_id: 1,
_name: 1,
feeClassifications: {
$filter: {
input: '$feeClassifications',
as: 'item',
cond: { $not: {$gt: ['$$item._trashed', null] } }
}
}
}}
])
But I also want to filter the nested array fees
. I've tried a few things including:
Permit.aggregate([
{ $match: { _id: mongoose.Types.ObjectId(req.params.id) }},
{ $project: {
_id: 1,
_name: 1,
feeClassifications: {
$filter: {
input: '$feeClassifications',
as: 'item',
cond: { $not: {$gt: ['$$item._trashed', null] } }
},
fees: {
$filter: {
input: '$fees',
as: 'fee',
cond: { $not: {$gt: ['$$fee._trashed', null] } }
}
}
}
}}
])
Which seems to follow the mongodb docs the closest. But I get the error:
this object is already an operator expression, and can't be used as a document expression (at 'fees')
Update: -----------
As requested, here's a sample document:
{
"_id" : ObjectId("57803fcd982971e403e3e879"),
"_updated" : ISODate("2016-07-11T19:24:27.204Z"),
"_created" : ISODate("2016-07-09T00:05:33.274Z"),
"name" : "Single Event",
"feeClassifications" : [
{
"_updated" : ISODate("2016-07-11T19:05:52.418Z"),
"_created" : ISODate("2016-07-11T17:49:12.247Z"),
"name" : "Event Type 1",
"_id" : ObjectId("5783dc18e09be99840fad29f"),
"fees" : [
{
"_updated" : ISODate("2016-07-11T18:51:10.259Z"),
"_created" : ISODate("2016-07-11T18:41:16.110Z"),
"name" : "Basic Fee",
"amount" : 156.5,
"_id" : ObjectId("5783e84cc46a883349bb2339")
},
{
"_updated" : ISODate("2016-07-11T19:05:52.419Z"),
"_created" : ISODate("2016-07-11T19:05:47.340Z"),
"name" : "Secondary Fee",
"amount" : 50,
"_id" : ObjectId("5783ee0bad7bf8774f6f9b5f"),
"_trashed" : ISODate("2016-07-11T19:05:52.410Z")
}
]
},
{
"_updated" : ISODate("2016-07-11T18:22:21.567Z"),
"_created" : ISODate("2016-07-11T18:22:21.567Z"),
"name" : "Event Type 2",
"_id" : ObjectId("5783e3dd540078de45bbbfaf"),
"_trashed" : ISODate("2016-07-11T19:24:27.203Z")
}
]
}
And here's the desired output ("trashed" subdocuments are excluded from BOTH feeClassifications
AND fees
):
{
"_id" : ObjectId("57803fcd982971e403e3e879"),
"_updated" : ISODate("2016-07-11T19:24:27.204Z"),
"_created" : ISODate("2016-07-09T00:05:33.274Z"),
"name" : "Single Event",
"feeClassifications" : [
{
"_updated" : ISODate("2016-07-11T19:05:52.418Z"),
"_created" : ISODate("2016-07-11T17:49:12.247Z"),
"name" : "Event Type 1",
"_id" : ObjectId("5783dc18e09be99840fad29f"),
"fees" : [
{
"_updated" : ISODate("2016-07-11T18:51:10.259Z"),
"_created" : ISODate("2016-07-11T18:41:16.110Z"),
"name" : "Basic Fee",
"amount" : 156.5,
"_id" : ObjectId("5783e84cc46a883349bb2339")
}
]
}
]
}
答案 0 :(得分:2)
由于我们要过滤外部和内部数组字段,我们可以使用$map
变量运算符,它返回一个包含我们想要的“值”的数组。
在$map
表达式中,我们提供了一个逻辑$cond
itional $filter
,用于从文档和子文档数组字段中删除不匹配的文档。
条件为$lt
,当子文档和/或子文档数组字段中不存在“_trashed”字段时,该条件返回true。
请注意,在$cond
表达式中,我们也会为<false case>
返回false。当然,我们需要对$map
结果应用过滤器,以删除所有false
。
Permit.aggregate(
[
{ "$match": { "_id": mongoose.Types.ObjectId(req.params.id) } },
{ "$project": {
"_updated": 1,
"_created": 1,
"name": 1,
"feeClassifications": {
"$filter": {
"input": {
"$map": {
"input": "$feeClassifications",
"as": "fclass",
"in": {
"$cond": [
{ "$lt": [ "$$fclass._trashed", 0 ] },
{
"_updated": "$$fclass._updated",
"_created": "$$fclass._created",
"name": "$$fclass.name",
"_id": "$$fclass._id",
"fees": {
"$filter": {
"input": "$$fclass.fees",
"as": "fees",
"cond": { "$lt": [ "$$fees._trashed", 0 ] }
}
}
},
false
]
}
}
},
"as": "cls",
"cond": "$$cls"
}
}
}}
]
)
在即将发布的MongoDB版本中(截至撰写本文时及MongoDB 3.3.5版本),您可以使用$cond
表达式替换$map
表达式中的$switch
表达式:< / p>
Permit.aggregate(
[
{ "$match": { "_id": mongoose.Types.ObjectId(req.params.id) } },
{ "$project": {
"_updated": 1,
"_created": 1,
"name": 1,
"feeClassifications": {
"$filter": {
"input": {
"$map": {
"input": "$feeClassifications",
"as": "fclass",
"in": {
"$switch": {
"branches": [
{
"case": { "$lt": [ "$$fclass._trashed", 0 ] },
"then": {
"_updated": "$$fclass._updated",
"_created": "$$fclass._created",
"name": "$$fclass.name",
"_id": "$$fclass._id",
"fees": {
"$filter": {
"input": "$$fclass.fees",
"as": "fees",
"cond": { "$lt": [ "$$fees._trashed", 0 ] }
}
}
}
}
],
"default": false
}
}
}
},
"as": "cls",
"cond": "$$cls"
}
}
}}
]
)
答案 1 :(得分:0)
对于更复杂的bigdats,这将不必要地困难。 只需在$ filter输入中添加点注释字段即可对其进行编辑。您可以通过点注释将文档搜索到JSON的任何深度,而无需进一步复杂的$ filter映射。
"$filter":{
"input": "$feeClassifications._trashed",
"as": "trashed",
"cond": { "$lt": [ "$$trashed._trashed", 0 ] }
}