如何对 MongoDB 中嵌入式文档数组进行筛选查询?
为此,在 MongoDB 中使用 aggregate()。我们创建一个带有以下文档的集合:
> db.demo736.insertOne( ... { ... "_id": "101", ... "details1": [ ... { ... "details2": [ ... { ... "details3": { ... "Name": "John" ... } ... } ... ] ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : "101" } > db.demo736.insertOne( ... { ... "_id": "102", ... "details1": [ ... { ... "details2": [ ... { ... "details3": { ... "Name": "Robert" ... } ... } ... ] ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : "102" }
使用 find() 方法从集合中显示所有文档:
> db.demo736.find();
这将产生以下输出:
{ "_id" : "101", "details1" : [ { "details2" : [ { "details3" : { "Name" : "John" } } ] } ] } { "_id" : "102", "details1" : [ { "details2" : [ { "details3" : { "Name" : "Robert" } } ] } ] }
以下是 MongoDB 中过滤嵌入式文档数组(3 级)的查询:
> db.demo736.aggregate([ ... { ... "$unwind": "$details1" ... }, ... { ... "$unwind": "$details1.details2" ... }, ... { ... "$match": { ... "details1.details2.details3.Name": "Robert" ... } ... }, ... { ... $project: { ... _id: 0, ... Name: "$details1.details2.details3", ... } ... } ... ])
这将产生以下输出:
{ "Name" : { "Name" : "Robert" } }
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