如何使用Go Map从Mongo检索非结构化数据形式

Question

I'm trying to retrieve data using go map. The data in mongo is like

"_id" : ObjectId("56bf128f5a9a6a0ebfdd5075"),
    "deadLine" : {
      "Start_time" : ISODate("2016-05-24T00:00:00Z"),
      "End_time" : ISODate("2016-05-29T00:00:00Z")
    },
    "taskData" : {
      "Task_content" : "Something",
      "Priority" : "3"
    },
    "group" : {
      "1" : {
      "grp_name" : "grp"
      },
      "2" : {
      "grp_name" : "secondGrp"
      }
    }

And I want to retrieve all records according to Priority.

the sample code which i tried ...

var m []bson.M
    err := collection.Find(bson.M{"taskData":bson.M{"Priority" : "2"}}).All(&m) // stuck here in `Find()`
    if err != nil {
        fmt.Println("Error : ",err)
    }else{
      fmt.Println("Map : ",m)
    }
  }

If i use err := collection.Find(bson.M{"_id":bson.ObjectIdHex("56bf128f5a9a6a0ebfdd5075")}).All(&m) then it fetch all records. Kindly correct my mistake.

Thanks in advance

Answer 1

var m []bson.M
    err := collection.Find(bson.M{"taskData.Priority" : "2"}).All(&m) 
    if err != nil {
        fmt.Println("Error : ",err)
    }else{
      fmt.Println("Map : ",m)
    }
  }

Here is the description https://docs.mongodb.org/manual/tutorial/query-documents/#equality-match-on-fields-within-an-embedded-document