匹配包含MongoDB中提供的数组的任意组合的数组字段？
将$nin运算符与$elemMatch和$not一起使用。为了理解这个概念，让我们用文档创建一个集合。使用文档创建集合的查询如下-
> db.combinationOfArrayDemo.insertOne({"StudentName":"Larry","StudentAge":21,"StudentFavouriteTechnicalSubject":["C","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f77cc8d10a061296a3c58")
}
> db.combinationOfArrayDemo.insertOne({"StudentName":"Mike","StudentAge":23,"StudentFavouriteTechnicalSubject":["C++","Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f77dc8d10a061296a3c59")
}
> db.combinationOfArrayDemo.insertOne({"StudentName":"David","StudentAge":22,"StudentFavouriteTechnicalSubject":["Java"]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f77f48d10a061296a3c5a")
}在find()method的帮助下显示集合中的所有文档。查询如下-
> db.combinationOfArrayDemo.find().pretty();
以下是输出-
{
"_id" : ObjectId("5c7f77cc8d10a061296a3c58"),
"StudentName" : "Larry",
"StudentAge" : 21,
"StudentFavouriteTechnicalSubject" : [
"C",
"Java"
]
}
{
"_id" : ObjectId("5c7f77dc8d10a061296a3c59"),
"StudentName" : "Mike",
"StudentAge" : 23,
"StudentFavouriteTechnicalSubject" : [
"C++",
"Java"
]
}
{
"_id" : ObjectId("5c7f77f48d10a061296a3c5a"),
"StudentName" : "David",
"StudentAge" : 22,
"StudentFavouriteTechnicalSubject" : [
"Java"
]
}这是用于匹配包含MongoDB中提供的数组的任何组合的数组字段的查询-
> db.combinationOfArrayDemo.find({StudentFavouriteTechnicalSubject: {$not: {$elemMatch:
{$nin: ['C++', 'Java']}}}}).pretty();以下是输出-
{
"_id" : ObjectId("5c7f77dc8d10a061296a3c59"),
"StudentName" : "Mike",
"StudentAge" : 23,
"StudentFavouriteTechnicalSubject" : [
"C++",
"Java"
]
}
{
"_id" : ObjectId("5c7f77f48d10a061296a3c5a"),
"StudentName" : "David",
"StudentAge" : 22,
"StudentFavouriteTechnicalSubject" : [
"Java"
]
}