Java 如何获取文档的另一个嵌套列表的嵌套记录?
我在检索另一个嵌套列表的嵌套文档对象时遇到困难。请帮我解决同样的问题。我的mongoDB文档如下:Java 如何获取文档的另一个嵌套列表的嵌套记录?,java,mongodb,mongodb-query,aggregation-framework,spring-data-mongodb,Java,Mongodb,Mongodb Query,Aggregation Framework,Spring Data Mongodb,我在检索另一个嵌套列表的嵌套文档对象时遇到困难。请帮我解决同样的问题。我的mongoDB文档如下: { "_id" : "PT5", "departmentId" : "DEPT5", "subDepartmentList" : [ { "subDepartmentId" : "SUBDEPT19", "subDepartmentName" : "X-Ray", "labServiceList" : [
{
"_id" : "PT5",
"departmentId" : "DEPT5",
"subDepartmentList" : [
{
"subDepartmentId" : "SUBDEPT19",
"subDepartmentName" : "X-Ray",
"labServiceList" : [
{
"_id" : "123abc",
"subDepartmentId" : "SUBDEPT19",
"labServiceName" : "serviceOne"
},
{
"_id" : "123def",
"subDepartmentId" : "SUBDEPT19",
"labServiceName" : "hello",
}
]
},
{
"subDepartmentId" : "SUBDEPT21",
"subDepartmentName" : "Haemotology",
"labServiceList" : [
{
"_id" : "456abc",
"subDepartmentId" : "SUBDEPT21",
"labServiceName" : "abcd",
}
]
}
]
}
在上面的文档中,我只想通过在本文档中使用其_id值ex:_id:123abc来检索labServiceList的一个对象。除了匹配的嵌套文档之外,我不想获取任何其他字段。我尝试了以下查询:
db.labServiceMasters.aggregate([
{"$project": {
"subDepartmentList": {"$filter": {
"input": '$subDepartmentList.labServiceList',
"as": 'labServiceList',
"cond": {"$eq": ['$$labServiceList._id', '123abc']}
}},
"_id": 0
}}
]
我也尝试过使用$map操作符,但没有任何东西妨碍我。请帮我解决这个问题。还请帮助我使用Java中的mongoTemplate编写相同的查询。任何建议都是可以接受的。提前感谢:-您实际上需要在$filter中嵌套一个$map,在$map中嵌套另一个$filter。并使用$arrayElemAt获取单个条目:
db.labServiceMasters.aggregate([
{ "$project": {
"subDepartmentList": {
"$arrayElemAt": [
{ "$filter": {
"input": {
"$map": {
"input": "$subDepartmentList",
"as": "sd",
"in": {
"$arrayElemAt": [
{ "$filter": {
"input": "$$sd.labServiceList",
"as": "ls",
"cond": { "$eq": [ "$$ls._id", "123abc" ] }
}},
0
]
}
}
},
"as": "sd",
"cond": { "$ne": [ "$$sd", null ] }
}},
0
]
}
}}
])
返回:
{
"_id" : "PT5",
"subDepartmentList" : {
"_id" : "123abc",
"subDepartmentId" : "SUBDEPT19",
"labServiceName" : "serviceOne"
}
}
对于spring mongodb,它是:
Aggregation aggregation = newAggregation(
project("subDepartmentList").and(new AggregationExpression() {
@Override
public DBObject toDbObject(AggregationOperationContext context) {
return new BasicDBObject(
"$arrayElemAt", Arrays.asList(
new BasicDBObject("$filter",
new BasicDBObject("input",
new BasicDBObject("$map",
new BasicDBObject("input","$subDepartmentList")
.append("as","sd")
.append("in",new BasicDBObject(
"$arrayElemAt", Arrays.asList(
new BasicDBObject("$filter",
new BasicDBObject("input","$$sd.labServiceList")
.append("as","ls")
.append("cond", new BasicDBObject("$eq", Arrays.asList("$$ls._id","123abc")))
),
0
)
))
)
)
.append("as","sd")
.append("$ne", Arrays.asList("$$sd", null))
),
0
)
);
}
}).as("subDepartmentList")
);
并序列化相同的内容:
{
"aggregate": "labServiceMasters",
"pipeline": [
{
"$project": {
"subDepartmentList": {
"$arrayElemAt": [
{
"$filter": {
"input": {
"$map": {
"input": "$subDepartmentList",
"as": "sd",
"in": {
"$arrayElemAt": [
{
"$filter": {
"input": "$$sd.labServiceList",
"as": "ls",
"cond": {
"$eq": [
"$$ls._id",
"123abc"
]
}
}
},
0.0
]
}
}
},
"as": "sd",
"$ne": [
"$$sd",
null
]
}
},
0.0
]
}
}
}
]
}
wowww:非常感谢尼尔:你救了我一天。。。这就是我想要的,我一整天都在努力实现。在你的回答中,我尝试了shell的问题,这很好。我无法尝试java查询,稍后我将尝试执行相同的查询,我确信即使这样也能起作用:-再次感谢大家:-Neil我尝试过使用java查询,但没有成功,因为它会导致一些编译错误,我已经尝试了所有方法,但都不起作用。如果你能追踪到错误,请帮助我。由于我使用的是Spring,如果Java查询是使用mongoTemplate的,那么它将对我更有帮助。谢谢:-@user3418760这是直接从我的IDE中剪切粘贴的代码,所以它确实有效。如果你有问题,那是因为你自己在打字。我建议您从这里复制代码,只需使用它,直到您了解如何自己编写管道。还要检查您是否已将项目中的sping mongodb更新为最新版本。