missing type in composite literal in golang/mongodb aggregate query

I want to write mongo query in golang. my mongo query is -

aggregate([
    {$match: {$and :
        [
            {"stream" : "CS"},
            {"semester" : "sem3"},
            {"section" : "A"}
        ]

    }},
    {$unwind:  '$atndnc'},
    { $group: { _id:{rollno: "$atndnc.rollno",attend:"$atndnc.attend"},count: { $sum: 1 }}},
    {  $project:
    {  _id: '$_id.rollno',
        'attend' : '$_id.attend',
        'count' : '$count'
    }}
])

And my Go code is -

cond:=[]bson.M{
	bson.M{"$match": bson.M{"$and ":[]interface{}{
		bson.M{"stream" : srchobj.Stream},
		bson.M{"semester" : srchobj.Semester},
		bson.M{"section" : srchobj.Section},
		bson.M{"college_id":srchobj.College_id},
		bson.M{"date":bson.M{"$gt":srchobj.Startdate,"$lt":srchobj.Enddate}}}}},
	bson.M{"$unwind":  "$atndnc"},
	bson.M{"$group":bson.M{"_id":{"rollno":bson.M{"$atndnc.rollno"},"attend":bson.M{"$atndnc.attend"}},"count":bson.M{"$sum":1}}},
	bson.M{"$project":bson.M{"_id":"$_id.rollno","count":"$_id.count"}}}

but it give the error "missing type in composite literal" in

	bson.M{"$group":bson.M{"_id":{"rollno":bson.M{"$atndnc.rollno"},"attend":bson.M{"$atndnc.attend"}},"count":bson.M{"$sum":1}}},

in this line.what should i do now?

You have a missing type declaration on a set of braces in your $group query:

I would assume should be:

there are also a few other initialization things like initializations with just a string key (remember, a bson.M is just an alias for map[string]interface{}

Thanks for your support.I got the desired output by doing this.

cond :=[]bson.M{
	bson.M{"$match": bson.M{
			"stream" : srchobj.Stream,
			"semester" : srchobj.Semester,
			"section" : srchobj.Section,
			"college_id":srchobj.College_id,
			"date":bson.M{
				"$gt":srchobj.Startdate,
				"$lt":srchobj.Enddate},
	 },
	},
	bson.M{"$unwind":  "$atndnc"},
	bson.M{"$group":bson.M{
		"_id":bson.M{
			"rollno":"$atndnc.rollno",
			"attend":"$atndnc.attend",
			"name":"$atndnc.name",
			},
		"count":bson.M{"$sum":1},
		},
	},
	bson.M{"$project":bson.M{
		"rollno":"$_id.rollno",
		"name":"$_id.name",
		"count":"$count",
		"attend":"$_id.attend",
		},
	},
	bson.M{"$sort":bson.M{"rollno":1}},
}