查询 MongoDB 中的数组数组
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Querying an array of arrays in MongoDB
提问by rajibdotnet
Say, I have a document like this..
说，我有一个这样的文件..
"ID" : "fruit1",
"Keys" : [["apple", "carrot", "banana"]]
How do I query for Keys = "carrot". None of the following syntax works.
如何查询 Keys = "carrot"。以下语法均无效。
db.myColl.results.find({ "Keys" : "carrot" });
db.myColl.results.find({ "Keys" : [["carrot"]] });
Following works though, but not helpful.
虽然以下有效，但没有帮助。
db.myColl.results.find({ "Keys" : [["apple", "carrot", "banana]]});
Any pointer to this query will be helpful. Thanks.
任何指向此查询的指针都会有所帮助。谢谢。
回答by RameshVel
Interesting question, This will do the trick
有趣的问题，这会解决问题
db.multiArr.find({'Keys':{$elemMatch:{$elemMatch:{$in:['carrot']}}}})
$elemMatchused to check if an element in an array matches the specified match expression.
so nested $elemMatchwill go deeper into nested arrays
$elemMatch用于检查数组中的元素是否与指定的匹配表达式匹配。所以嵌套$elemMatch将深入到嵌套数组中
Test data ? ?
测试数据 ？?
db.multiArr.insert({"ID" : "fruit1","Keys" : [["apple", "carrot", "banana"]]})
db.multiArr.insert({"ID" : "fruit2","Keys" : [["apple", "orange", "banana"]]})
db.multiArr.find({'Keys':{$elemMatch:{$elemMatch:{$in:['carrot']}}}})
{ "_id" : ObjectId("506555212aeb79b5f7374cbf"), "ID" : "fruit1", "Keys" : [ [ "apple", "carrot", "banana" ] ] }
db.multiArr.find({'Keys':{$elemMatch:{$elemMatch:{$in:['banana']}}}})
{ "_id" : ObjectId("506555212aeb79b5f7374cbf"), "ID" : "fruit1", "Keys" : [ [ "apple", "carrot", "banana" ] ] }
{ "_id" : ObjectId("5065587e2aeb79b5f7374cc0"), "ID" : "fruit2", "Keys" : [ [ "apple", "orange", "banana" ] ] }
回答by KARTHIKEYAN.A
if you want to find array of first position data, use 0 as reference index to get data in nested array.
如果要查找第一个位置数据的数组，请使用 0 作为参考索引以获取嵌套数组中的数据。
db.getCollection('routes').find({"routeId" : 12,'routes._id':ObjectId("598da27a713f3e6acd72287f"),'routes.0.stops.0.orders.0._id':ObjectId("598da27a713f3e6acd722887")})
