英文:
missing type in composite literal in golang/mongodb aggregate query
问题
我可以帮你翻译Mongo查询和Go代码。以下是翻译的结果：
Mongo查询：
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'}}])
Go代码：
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{"$group": bson.M{"_id": bson.M{"rollno": "$atndnc.rollno", "attend": "$atndnc.attend"}, "count": bson.M{"$sum": 1}}},bson.M{"$project": bson.M{"_id": "$_id.rollno", "count": "$_id.count"}},}
在这段代码中，你遇到了一个错误："missing type in composite literal"，出现在以下这行代码中：
bson.M{"$group":bson.M{"_id":bson.M{"rollno":bson.M{"$atndnc.rollno"},"attend":bson.M{"$atndnc.attend"}},"count":bson.M{"$sum":1}}},
这个错误是因为你在bson.M中使用了$atndnc.rollno和$atndnc.attend作为键名，但是它们应该是字符串而不是bson.M类型。你需要将它们改为字符串，如下所示：
bson.M{"$group":bson.M{"_id":bson.M{"rollno":"$atndnc.rollno","attend":"$atndnc.attend"},"count":bson.M{"$sum":1}}},
这样修改后的代码应该就没有错误了。希望对你有帮助！
英文:
I want to write mongo query in golang. my mongo query is -
aggregate([{$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{"$sum":1}}},
in this line.what should i do now?
答案1
得分: 2
你的$group查询中的一组大括号缺少类型声明：
{"rollno":bson.M{"$atndnc.rollno"},"attend":bson.M{"$atndnc.attend"}}
我认为应该是：
bson.M{"rollno":bson.M{"$atndnc.rollno"},"attend":bson.M{"$atndnc.attend":nil}}
还有一些其他的初始化问题，比如只用一个字符串键进行初始化（记住，bson.M只是map[string]interface{}的别名）。
英文:
You have a missing type declaration on a set of braces in your $group query:
I would assume should be:
there are also a few other initialization things like initializations with just a string key (remember, a bson.M is just an alias for map[string]interface{}
答案2
得分: 0
感谢您的支持。通过这样做，我得到了所需的输出。
cond := []bson.M{bson.M{"$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{"$sort": bson.M{"rollno": 1}},}
英文:
Thanks for your support.I got the desired output by doing this.
cond :=[]bson.M{bson.M{"$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}},}
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