MongoDB查询以过滤对象，其中嵌套数组中的所有元素均与条件匹配
为此，请使用aggregate()。首先让我们创建一个包含文档的集合-
> db.demo418.insertOne(
... {
... "details":[
... {
... "CountryName":"US",
... "Marks":45
... },
... {
... "CountryName":"US",
... "Marks":56
... },
...
... ],
... "Name":"John"
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e724324b912067e57771ae6")
}
> db.demo418.insertOne(
... {
... "details":[
... {
... "CountryName":"US",
... "Marks":78
... },
... {
... "CountryName":"UK",
... "Marks":97
... },
...
... ],
... "Name":"Mike"
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e724325b912067e57771ae7")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo418.find();
这将产生以下输出-
{ "_id" : ObjectId("5e724324b912067e57771ae6"), "details" : [ { "CountryName" : "US", "Marks" : 45 }, { "CountryName" : "US", "Marks" : 56 } ], "Name" : "John" }
{ "_id" : ObjectId("5e724325b912067e57771ae7"), "details" : [ { "CountryName" : "US", "Marks" : 78 }, { "CountryName" : "UK", "Marks" : 97 } ], "Name" : "Mike" }以下是过滤对象的查询，其中嵌套数组中的所有元素均符合条件-
> db.demo418.aggregate([
... {$unwind:"$details"},
... { $group: {
... _id: '$_id',
... details : { $first: '$details' },
... alldetails: { $sum: 1 },
... alldetailsmatch: { $sum: { $cond: [ { $eq: [ '$details.CountryName', "US" ] }, 1, 0 ] } },
... Name: { $first: '$Name' }
... }},
... { $project: {
... _id: 1,
... Name: 1,
... details: 1,
... arrayValue: { $cond: [ { $eq: [ '$alldetails', '$alldetailsmatch' ] }, 1, 0 ] }
... }},
... { $match: { 'arrayValue' : 1 } }
... ])这将产生以下输出-
{ "_id" : ObjectId("5e724324b912067e57771ae6"), "details" : { "CountryName" : "US", "Marks" : 45 }, "Name" : "John", "arrayValue" : 1 }