Javascript 如何计算字典'的平均值;s值由列表组成?蒙哥达
我有一个简单的JSON文件,其中包含几个学生的成绩(Notes是一个数组,其中包含科目名称及其成绩(Note))Javascript 如何计算字典'的平均值;s值由列表组成?蒙哥达,javascript,arrays,json,mongodb,aggregate,Javascript,Arrays,Json,Mongodb,Aggregate,我有一个简单的JSON文件,其中包含几个学生的成绩(Notes是一个数组,其中包含科目名称及其成绩(Note)) [{ "N° Apogée": "115635", "Nom": "Affelay", "Prénom": "Ibrahim", "CNE": &qu
[{
"N° Apogée": "115635",
"Nom": "Affelay",
"Prénom": "Ibrahim",
"CNE": "112789568",
"Notes": [{
"Module": "Base de données",
"Note": 17,
"validation": "V"
},
{
"Module": "Compilation",
"Note": 11,
"validation": "V"
},
{
"Module": "Reseaux Informatique",
"Note": 13,
"validation": "V"
},
{
"Module": "Recherche Operationnelle",
"Note": 11,
"validation": "V"
},
{
"Module": "Conception UML",
"Note": 11,
"validation": "V"
},
{
"Module": "C++",
"Note": 13,
"validation": "V"
}
]
},
{
"N° Apogée": "1620234",
"Nom": "John",
"Prénom": "Doe",
"CNE": "H146029920",
"Notes": [{
"Module": "Base de données",
"Note": 7,
"validation": "NV"
},
{
"Module": "Compilation",
"Note": 14,
"validation": "V"
},
{
"Module": "Reseaux Informatique",
"Note": 17,
"validation": "V"
},
{
"Module": "Recherche Operationnelle",
"Note": 9,
"validation": "NV"
},
{
"Module": "Conception UML",
"Note": 11,
"validation": "V"
},
{
"Module": "C++",
"Note": 15,
"validation": "V"
}
]
}
]
我想返回每个学生的平均成绩(注)。我尝试使用聚合:
db.exam.aggregate([{$group:{_id:"$Nom",Moyenne:{$avg :"$Notes.Note"}}}])
它返回:
{ "_id" : "John", "Moyenne" : null }
{ "_id" : "Xavi", "Moyenne" : null }
{ "_id" : "Lionel", "Moyenne" : null }
{ "_id" : "Pique", "Moyenne" : null }
{ "_id" : "Affelay", "Moyenne" : null }
似乎我无法从Notes数组中获取值Notes?这是问题吗?
我错过了什么