MongoDB 跨集合查询

如何解决MongoDB 跨集合查询

假设结构如下：

资产

{
    "_id" : LUUID("d34a3fed"),"name" : "A","records" : [ 
        LUUID("3627f3ac"),LUUID("80e9d125"),LUUID("4d5e8af5"),LUUID("17593a39"),}

记录

{
    "_id" : LUUID("3627f3ac"),"Fields" : [ 
        {
            "Name" : "foo","Value" : "bar",} 
    ],}

我的目标是使用 find() 或aggregate() 来交叉引用上述两个集合。这两个集合共享 LUUID 值。

{"records": "LUUID("3627f3ac")"}

{"_id": "LUUID("3627f3ac")"}

最终检索：

{"Fields.Name": "foo"}

记录集合的名称

解决方法

也许是这样的：

mongos> db.records.find()
{ "_id" : ObjectId("5ff8ccf9e0f1b975b90d7a86"),"fields" : [ { "name" : "foo","value" : "bar" } ] }
{ "_id" : ObjectId("5ff8ccf9e0f1b975b90d7a87"),"fields" : [ { "name" : "foo2","value" : "bar2" } ] }
{ "_id" : ObjectId("5ff8ccf9e0f1b975b90d7a88"),"fields" : [ { "name" : "foo3","value" : "bar3" } ] }
mongos> db.assest.find()
{ "_id" : ObjectId("5ff8cd72e0f1b975b90d7a87"),"name" : "A","records" : [ ObjectId("5ff8ccf9e0f1b975b90d7a86"),ObjectId("5ff8ccf9e0f1b975b90d7a87") ] }
mongos> db.assest.aggregate([   { $lookup:{ from:"records",localField:"records",foreignField:"_id",as:"match"    }  },{$unwind:"$match"},{$unwind:"$match.fields"},{$project:{ "Fields_name":"$match.fields.name",_id:0}}   ])
{ "Fields_name" : "foo" }
{ "Fields_name" : "foo2" }
mongos>